diff options
| -rw-r--r-- | Documentation/RCU/rcu.txt | 10 | ||||
| -rw-r--r-- | Documentation/RCU/whatisRCU.txt | 8 | ||||
| -rw-r--r-- | include/linux/init_task.h | 6 | ||||
| -rw-r--r-- | include/linux/rcupdate.h | 4 | ||||
| -rw-r--r-- | include/linux/rcupreempt.h | 140 | ||||
| -rw-r--r-- | include/linux/rcupreempt_trace.h | 97 | ||||
| -rw-r--r-- | include/linux/sched.h | 13 | ||||
| -rw-r--r-- | init/Kconfig | 20 | ||||
| -rw-r--r-- | kernel/Makefile | 2 | ||||
| -rw-r--r-- | kernel/rcupreempt.c | 1518 | ||||
| -rw-r--r-- | kernel/rcupreempt_trace.c | 335 | ||||
| -rw-r--r-- | lib/Kconfig.debug | 2 |
12 files changed, 13 insertions, 2142 deletions
diff --git a/Documentation/RCU/rcu.txt b/Documentation/RCU/rcu.txt index 7aa2002ade77..2a23523ce471 100644 --- a/Documentation/RCU/rcu.txt +++ b/Documentation/RCU/rcu.txt @@ -36,7 +36,7 @@ o How can the updater tell when a grace period has completed executed in user mode, or executed in the idle loop, we can safely free up that item. - Preemptible variants of RCU (CONFIG_PREEMPT_RCU) get the + Preemptible variants of RCU (CONFIG_TREE_PREEMPT_RCU) get the same effect, but require that the readers manipulate CPU-local counters. These counters allow limited types of blocking within RCU read-side critical sections. SRCU also uses @@ -79,10 +79,10 @@ o I hear that RCU is patented? What is with that? o I hear that RCU needs work in order to support realtime kernels? This work is largely completed. Realtime-friendly RCU can be - enabled via the CONFIG_PREEMPT_RCU kernel configuration parameter. - However, work is in progress for enabling priority boosting of - preempted RCU read-side critical sections. This is needed if you - have CPU-bound realtime threads. + enabled via the CONFIG_TREE_PREEMPT_RCU kernel configuration + parameter. However, work is in progress for enabling priority + boosting of preempted RCU read-side critical sections. This is + needed if you have CPU-bound realtime threads. o Where can I find more information on RCU? diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index 97ded2432c59..e41a7fecf0d3 100644 --- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -136,10 +136,10 @@ rcu_read_lock() Used by a reader to inform the reclaimer that the reader is entering an RCU read-side critical section. It is illegal to block while in an RCU read-side critical section, though - kernels built with CONFIG_PREEMPT_RCU can preempt RCU read-side - critical sections. Any RCU-protected data structure accessed - during an RCU read-side critical section is guaranteed to remain - unreclaimed for the full duration of that critical section. + kernels built with CONFIG_TREE_PREEMPT_RCU can preempt RCU + read-side critical sections. Any RCU-protected data structure + accessed during an RCU read-side critical section is guaranteed to + remain unreclaimed for the full duration of that critical section. Reference counts may be used in conjunction with RCU to maintain longer-term references to data structures. diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 971a968831bf..79d4baee31b6 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -94,11 +94,7 @@ extern struct group_info init_groups; # define CAP_INIT_BSET CAP_INIT_EFF_SET #endif -#ifdef CONFIG_PREEMPT_RCU -#define INIT_TASK_RCU_PREEMPT(tsk) \ - .rcu_read_lock_nesting = 0, \ - .rcu_flipctr_idx = 0, -#elif defined(CONFIG_TREE_PREEMPT_RCU) +#ifdef CONFIG_TREE_PREEMPT_RCU #define INIT_TASK_RCU_PREEMPT(tsk) \ .rcu_read_lock_nesting = 0, \ .rcu_read_unlock_special = 0, \ diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 26892f5e7bd8..ec90fc34fea9 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -68,11 +68,9 @@ extern int rcu_scheduler_active; #if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU) #include <linux/rcutree.h> -#elif defined(CONFIG_PREEMPT_RCU) -#include <linux/rcupreempt.h> #else #error "Unknown RCU implementation specified to kernel configuration" -#endif /* #else #if defined(CONFIG_CLASSIC_RCU) */ +#endif #define RCU_HEAD_INIT { .next = NULL, .func = NULL } #define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT diff --git a/include/linux/rcupreempt.h b/include/linux/rcupreempt.h deleted file mode 100644 index a42ab88e9210..000000000000 --- a/include/linux/rcupreempt.h +++ /dev/null @@ -1,140 +0,0 @@ -/* - * Read-Copy Update mechanism for mutual exclusion (RT implementation) - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. - * - * Copyright (C) IBM Corporation, 2006 - * - * Author: Paul McKenney <paulmck@us.ibm.com> - * - * Based on the original work by Paul McKenney <paul.mckenney@us.ibm.com> - * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. - * Papers: - * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf - * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) - * - * For detailed explanation of Read-Copy Update mechanism see - - * Documentation/RCU - * - */ - -#ifndef __LINUX_RCUPREEMPT_H -#define __LINUX_RCUPREEMPT_H - -#include <linux/cache.h> -#include <linux/spinlock.h> -#include <linux/threads.h> -#include <linux/smp.h> -#include <linux/cpumask.h> -#include <linux/seqlock.h> - -extern void rcu_sched_qs(int cpu); -static inline void rcu_bh_qs(int cpu) { } - -/* - * Someone might want to pass call_rcu_bh as a function pointer. - * So this needs to just be a rename and not a macro function. - * (no parentheses) - */ -#define call_rcu_bh call_rcu - -/** - * call_rcu_sched - Queue RCU callback for invocation after sched grace period. - * @head: structure to be used for queueing the RCU updates. - * @func: actual update function to be invoked after the grace period - * - * The update function will be invoked some time after a full - * synchronize_sched()-style grace period elapses, in other words after - * all currently executing preempt-disabled sections of code (including - * hardirq handlers, NMI handlers, and local_irq_save() blocks) have - * completed. - */ -extern void call_rcu_sched(struct rcu_head *head, - void (*func)(struct rcu_head *head)); - -extern void __rcu_read_lock(void); -extern void __rcu_read_unlock(void); -extern int rcu_needs_cpu(int cpu); - -#define __rcu_read_lock_bh() { rcu_read_lock(); local_bh_disable(); } -#define __rcu_read_unlock_bh() { local_bh_enable(); rcu_read_unlock(); } - -extern void __synchronize_sched(void); - -static inline void synchronize_rcu_expedited(void) -{ - synchronize_rcu(); /* Placeholder for new rcupreempt implementation. */ -} - -static inline void synchronize_rcu_bh_expedited(void) -{ - synchronize_rcu_bh(); /* Placeholder for new rcupreempt impl. */ -} - -extern void __rcu_init(void); -extern void rcu_init_sched(void); -extern void rcu_check_callbacks(int cpu, int user); -extern void rcu_restart_cpu(int cpu); -extern long rcu_batches_completed(void); - -/* - * Return the number of RCU batches processed thus far. Useful for debug - * and statistic. The _bh variant is identifcal to straight RCU - */ -static inline long rcu_batches_completed_bh(void) -{ - return rcu_batches_completed(); -} - -static inline void exit_rcu(void) -{ -} - -#ifdef CONFIG_RCU_TRACE -struct rcupreempt_trace; -extern long *rcupreempt_flipctr(int cpu); -extern long rcupreempt_data_completed(void); -extern int rcupreempt_flip_flag(int cpu); -extern int rcupreempt_mb_flag(int cpu); -extern char *rcupreempt_try_flip_state_name(void); -extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu); -#endif - -struct softirq_action; - -#ifdef CONFIG_NO_HZ -extern void rcu_enter_nohz(void); -extern void rcu_exit_nohz(void); -#else -# define rcu_enter_nohz() do { } while (0) -# define rcu_exit_nohz() do { } while (0) -#endif - -/* - * A context switch is a grace period for rcupreempt synchronize_rcu() - * only during early boot, before the scheduler has been initialized. - * So, how the heck do we get a context switch? Well, if the caller - * invokes synchronize_rcu(), they are willing to accept a context - * switch, so we simply pretend that one happened. - * - * After boot, there might be a blocked or preempted task in an RCU - * read-side critical section, so we cannot then take the fastpath. - */ -static inline int rcu_blocking_is_gp(void) -{ - return num_online_cpus() == 1 && !rcu_scheduler_active; -} - -#endif /* __LINUX_RCUPREEMPT_H */ diff --git a/include/linux/rcupreempt_trace.h b/include/linux/rcupreempt_trace.h deleted file mode 100644 index b99ae073192a..000000000000 --- a/include/linux/rcupreempt_trace.h +++ /dev/null @@ -1,97 +0,0 @@ -/* - * Read-Copy Update mechanism for mutual exclusion (RT implementation) - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. - * - * Copyright (C) IBM Corporation, 2006 - * - * Author: Paul McKenney <paulmck@us.ibm.com> - * - * Based on the original work by Paul McKenney <paul.mckenney@us.ibm.com> - * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. - * Papers: - * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf - * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) - * - * For detailed explanation of the Preemptible Read-Copy Update mechanism see - - * http://lwn.net/Articles/253651/ - */ - -#ifndef __LINUX_RCUPREEMPT_TRACE_H -#define __LINUX_RCUPREEMPT_TRACE_H - -#include <linux/types.h> -#include <linux/kernel.h> - -#include <asm/atomic.h> - -/* - * PREEMPT_RCU data structures. - */ - -struct rcupreempt_trace { - long next_length; - long next_add; - long wait_length; - long wait_add; - long done_length; - long done_add; - long done_remove; - atomic_t done_invoked; - long rcu_check_callbacks; - atomic_t rcu_try_flip_1; - atomic_t rcu_try_flip_e1; - long rcu_try_flip_i1; - long rcu_try_flip_ie1; - long rcu_try_flip_g1; - long rcu_try_flip_a1; - long rcu_try_flip_ae1; - long rcu_try_flip_a2; - long rcu_try_flip_z1; - long rcu_try_flip_ze1; - long rcu_try_flip_z2; - long rcu_try_flip_m1; - long rcu_try_flip_me1; - long rcu_try_flip_m2; -}; - -#ifdef CONFIG_RCU_TRACE -#define RCU_TRACE(fn, arg) fn(arg); -#else -#define RCU_TRACE(fn, arg) -#endif - -extern void rcupreempt_trace_move2done(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_move2wait(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_1(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_e1(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_i1(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_ie1(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_g1(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_a1(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_ae1(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_a2(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_z1(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_ze1(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_z2(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_m1(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_me1(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_try_flip_m2(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_check_callbacks(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_done_remove(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_invoke(struct rcupreempt_trace *trace); -extern void rcupreempt_trace_next_add(struct rcupreempt_trace *trace); - -#endif /* __LINUX_RCUPREEMPT_TRACE_H */ diff --git a/include/linux/sched.h b/include/linux/sched.h index d7f98f637a2a..bfca26d63b13 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1205,11 +1205,6 @@ struct task_struct { unsigned int policy; cpumask_t cpus_allowed; -#ifdef CONFIG_PREEMPT_RCU - int rcu_read_lock_nesting; - int rcu_flipctr_idx; -#endif /* #ifdef CONFIG_PREEMPT_RCU */ - #ifdef CONFIG_TREE_PREEMPT_RCU int rcu_read_lock_nesting; char rcu_read_unlock_special; @@ -1744,14 +1739,6 @@ static inline void rcu_copy_process(struct task_struct *p) INIT_LIST_HEAD(&p->rcu_node_entry); } -#elif defined(CONFIG_PREEMPT_RCU) - -static inline void rcu_copy_process(struct task_struct *p) -{ - p->rcu_read_lock_nesting = 0; - p->rcu_flipctr_idx = 0; -} - #else static inline void rcu_copy_process(struct task_struct *p) diff --git a/init/Kconfig b/init/Kconfig index f88da2d1c1fb..8e8b76d8a272 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -324,17 +324,6 @@ config TREE_RCU thousands of CPUs. It also scales down nicely to smaller systems. -config PREEMPT_RCU - bool "Preemptible RCU" - depends on PREEMPT - help - This option reduces the latency of the kernel by making certain - RCU sections preemptible. Normally RCU code is non-preemptible, if - this option is selected then read-only RCU sections become - preemptible. This helps latency, but may expose bugs due to - now-naive assumptions about each RCU read-side critical section - remaining on a given CPU through its execution. - config TREE_PREEMPT_RCU bool "Preemptable tree-based hierarchical RCU" depends on PREEMPT @@ -348,7 +337,7 @@ endchoice config RCU_TRACE bool "Enable tracing for RCU" - depends on TREE_RCU || PREEMPT_RCU || TREE_PREEMPT_RCU + depends on TREE_RCU || TREE_PREEMPT_RCU help This option provides tracing in RCU which presents stats in debugfs for debugging RCU implementation. @@ -395,13 +384,6 @@ config TREE_RCU_TRACE TREE_PREEMPT_RCU implementations, permitting Makefile to trivially select kernel/rcutree_trace.c. -config PREEMPT_RCU_TRACE - def_bool RCU_TRACE && PREEMPT_RCU - select DEBUG_FS - help - This option provides tracing for the PREEMPT_RCU implementation, - permitting Makefile to trivially select kernel/rcupreempt_trace.c. - endmenu # "RCU Subsystem" config IKCONFIG diff --git a/kernel/Makefile b/kernel/Makefile index 1a38b4789dda..b833bd5cc127 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -82,9 +82,7 @@ obj-$(CONFIG_SECCOMP) += seccomp.o obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o obj-$(CONFIG_TREE_RCU) += rcutree.o obj-$(CONFIG_TREE_PREEMPT_RCU) += rcutree.o -obj-$(CONFIG_PREEMPT_RCU) += rcupreempt.o obj-$(CONFIG_TREE_RCU_TRACE) += rcutree_trace.o -obj-$(CONFIG_PREEMPT_RCU_TRACE) += rcupreempt_trace.o obj-$(CONFIG_RELAY) += relay.o obj-$(CONFIG_SYSCTL) += utsname_sysctl.o obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c deleted file mode 100644 index 0053ce56e326..000000000000 --- a/kernel/rcupreempt.c +++ /dev/null @@ -1,1518 +0,0 @@ -/* - * Read-Copy Update mechanism for mutual exclusion, realtime implementation - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. - * - * Copyright IBM Corporation, 2006 - * - * Authors: Paul E. McKenney <paulmck@us.ibm.com> - * With thanks to Esben Nielsen, Bill Huey, and Ingo Molnar - * for pushing me away from locks and towards counters, and - * to Suparna Bhattacharya for pushing me completely away - * from atomic instructions on the read side. - * - * - Added handling of Dynamic Ticks - * Copyright 2007 - Paul E. Mckenney <paulmck@us.ibm.com> - * - Steven Rostedt <srostedt@redhat.com> - * - * Papers: http://www.rdrop.com/users/paulmck/RCU - * - * Design Document: http://lwn.net/Articles/253651/ - * - * For detailed explanation of Read-Copy Update mechanism see - - * Documentation/RCU/ *.txt - * - */ -#include <linux/types.h> -#include <linux/kernel.h> -#include <linux/init.h> -#include <linux/spinlock.h> -#include <linux/smp.h> -#include <linux/rcupdate.h> -#include <linux/interrupt.h> -#include <linux/sched.h> -#include <asm/atomic.h> -#include <linux/bitops.h> -#include <linux/module.h> -#include <linux/kthread.h> -#include <linux/completion.h> -#include <linux/moduleparam.h> -#include <linux/percpu.h> -#include <linux/notifier.h> -#include <linux/cpu.h> -#include <linux/random.h> -#include <linux/delay.h> -#include <linux/cpumask.h> -#include <linux/rcupreempt_trace.h> -#include <asm/byteorder.h> - -/* - * PREEMPT_RCU data structures. - */ - -/* - * GP_STAGES specifies the number of times the state machine has - * to go through the all the rcu_try_flip_states (see below) - * in a single Grace Period. - * - * GP in GP_STAGES stands for Grace Period ;) - */ -#define GP_STAGES 2 -struct rcu_data { - spinlock_t lock; /* Protect rcu_data fields. */ - long completed; /* Number of last completed batch. */ - int waitlistcount; - struct rcu_head *nextlist; - struct rcu_head **nexttail; - struct rcu_head *waitlist[GP_STAGES]; - struct rcu_head **waittail[GP_STAGES]; - struct rcu_head *donelist; /* from waitlist & waitschedlist */ - struct rcu_head **donetail; - long rcu_flipctr[2]; - struct rcu_head *nextschedlist; - struct rcu_head **nextschedtail; - struct rcu_head *waitschedlist; - struct rcu_head **waitschedtail; - int rcu_sched_sleeping; -#ifdef CONFIG_RCU_TRACE - struct rcupreempt_trace trace; -#endif /* #ifdef CONFIG_RCU_TRACE */ -}; - -/* - * States for rcu_try_flip() and friends. - */ - -enum rcu_try_flip_states { - - /* - * Stay here if nothing is happening. Flip the counter if somthing - * starts happening. Denoted by "I" - */ - rcu_try_flip_idle_state, - - /* - * Wait here for all CPUs to notice that the counter has flipped. This - * prevents the old set of counters from ever being incremented once - * we leave this state, which in turn is necessary because we cannot - * test any individual counter for zero -- we can only check the sum. - * Denoted by "A". - */ - rcu_try_flip_waitack_state, - - /* - * Wait here for the sum of the old per-CPU counters to reach zero. - * Denoted by "Z". - */ - rcu_try_flip_waitzero_state, - - /* - * Wait here for each of the other CPUs to execute a memory barrier. - * This is necessary to ensure that these other CPUs really have - * completed executing their RCU read-side critical sections, despite - * their CPUs wildly reordering memory. Denoted by "M". - */ - rcu_try_flip_waitmb_state, -}; - -/* - * States for rcu_ctrlblk.rcu_sched_sleep. - */ - -enum rcu_sched_sleep_states { - rcu_sched_not_sleeping, /* Not sleeping, callbacks need GP. */ - rcu_sched_sleep_prep, /* Thinking of sleeping, rechecking. */ - rcu_sched_sleeping, /* Sleeping, awaken if GP needed. */ -}; - -struct rcu_ctrlblk { - spinlock_t fliplock; /* Protect state-machine transitions. */ - long completed; /* Number of last completed batch. */ - enum rcu_try_flip_states rcu_try_flip_state; /* The current state of - the rcu state machine */ - spinlock_t schedlock; /* Protect rcu_sched sleep state. */ - enum rcu_sched_sleep_states sched_sleep; /* rcu_sched state. */ - wait_queue_head_t sched_wq; /* Place for rcu_sched to sleep. */ -}; - -struct rcu_dyntick_sched { - int dynticks; - int dynticks_snap; - int sched_qs; - int sched_qs_snap; - int sched_dynticks_snap; -}; - -static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_dyntick_sched, rcu_dyntick_sched) = { - .dynticks = 1, -}; - -static int rcu_pending(int cpu); - -void rcu_sched_qs(int cpu) -{ - struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu); - - rdssp->sched_qs++; -} - -#ifdef CONFIG_NO_HZ - -void rcu_enter_nohz(void) -{ - static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1); - - smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ - __get_cpu_var(rcu_dyntick_sched).dynticks++; - WARN_ON_RATELIMIT(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1, &rs); -} - -void rcu_exit_nohz(void) -{ - static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1); - - __get_cpu_var(rcu_dyntick_sched).dynticks++; - smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ - WARN_ON_RATELIMIT(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1), - &rs); -} - -#endif /* CONFIG_NO_HZ */ - - -static DEFINE_PER_CPU(struct rcu_data, rcu_data); - -static struct rcu_ctrlblk rcu_ctrlblk = { - .fliplock = __SPIN_LOCK_UNLOCKED(rcu_ctrlblk.fliplock), - .completed = 0, - .rcu_try_flip_state = rcu_try_flip_idle_state, - .schedlock = __SPIN_LOCK_UNLOCKED(rcu_ctrlblk.schedlock), - .sched_sleep = rcu_sched_not_sleeping, - .sched_wq = __WAIT_QUEUE_HEAD_INITIALIZER(rcu_ctrlblk.sched_wq), -}; - -static struct task_struct *rcu_sched_grace_period_task; - -#ifdef CONFIG_RCU_TRACE -static char *rcu_try_flip_state_names[] = - { "idle", "waitack", "waitzero", "waitmb" }; -#endif /* #ifdef CONFIG_RCU_TRACE */ - -static DECLARE_BITMAP(rcu_cpu_online_map, NR_CPUS) __read_mostly - = CPU_BITS_NONE; - -/* - * Enum and per-CPU flag to determine when each CPU has seen - * the most recent counter flip. - */ - -enum rcu_flip_flag_values { - rcu_flip_seen, /* Steady/initial state, last flip seen. */ - /* Only GP detector can update. */ - rcu_flipped /* Flip just completed, need confirmation. */ - /* Only corresponding CPU can update. */ -}; -static DEFINE_PER_CPU_SHARED_ALIGNED(enum rcu_flip_flag_values, rcu_flip_flag) - = rcu_flip_seen; - -/* - * Enum and per-CPU flag to determine when each CPU has executed the - * needed memory barrier to fence in memory references from its last RCU - * read-side critical section in the just-completed grace period. - */ - -enum rcu_mb_flag_values { - rcu_mb_done, /* Steady/initial state, no mb()s required. */ - /* Only GP detector can update. */ - rcu_mb_needed /* Flip just completed, need an mb(). */ - /* Only corresponding CPU can update. */ -}; -static DEFINE_PER_CPU_SHARED_ALIGNED(enum rcu_mb_flag_values, rcu_mb_flag) - = rcu_mb_done; - -/* - * RCU_DATA_ME: find the current CPU's rcu_data structure. - * RCU_DATA_CPU: find the specified CPU's rcu_data structure. - */ -#define RCU_DATA_ME() (&__get_cpu_var(rcu_data)) -#define RCU_DATA_CPU(cpu) (&per_cpu(rcu_data, cpu)) - -/* - * Helper macro for tracing when the appropriate rcu_data is not - * cached in a local variable, but where the CPU number is so cached. - */ -#define RCU_TRACE_CPU(f, cpu) RCU_TRACE(f, &(RCU_DATA_CPU(cpu)->trace)); - -/* - * Helper macro for tracing when the appropriate rcu_data is not - * cached in a local variable. - */ -#define RCU_TRACE_ME(f) RCU_TRACE(f, &(RCU_DATA_ME()->trace)); - -/* - * Helper macro for tracing when the appropriate rcu_data is pointed - * to by a local variable. - */ -#define RCU_TRACE_RDP(f, rdp) RCU_TRACE(f, &((rdp)->trace)); - -#define RCU_SCHED_BATCH_TIME (HZ / 50) - -/* - * Return the number of RCU batches processed thus far. Useful - * for debug and statistics. - */ -long rcu_batches_completed(void) -{ - return rcu_ctrlblk.completed; -} -EXPORT_SYMBOL_GPL(rcu_batches_completed); - -void __rcu_read_lock(void) -{ - int idx; - struct task_struct *t = current; - int nesting; - - nesting = ACCESS_ONCE(t->rcu_read_lock_nesting); - if (nesting != 0) { - - /* An earlier rcu_read_lock() covers us, just count it. */ - - t->rcu_read_lock_nesting = nesting + 1; - - } else { - unsigned long flags; - - /* - * We disable interrupts for the following reasons: - * - If we get scheduling clock interrupt here, and we - * end up acking the counter flip, it's like a promise - * that we will never increment the old counter again. - * Thus we will break that promise if that - * scheduling clock interrupt happens between the time - * we pick the .completed field and the time that we - * increment our counter. - * - * - We don't want to be preempted out here. - * - * NMIs can still occur, of course, and might themselves - * contain rcu_read_lock(). - */ - - local_irq_save(flags); - - /* - * Outermost nesting of rcu_read_lock(), so increment - * the current counter for the current CPU. Use volatile - * casts to prevent the compiler from reordering. - */ - - idx = ACCESS_ONCE(rcu_ctrlblk.completed) & 0x1; - ACCESS_ONCE(RCU_DATA_ME()->rcu_flipctr[idx])++; - - /* - * Now that the per-CPU counter has been incremented, we - * are protected from races with rcu_read_lock() invoked - * from NMI handlers on this CPU. We can therefore safely - * increment the nesting counter, relieving further NMIs - * of the need to increment the per-CPU counter. - */ - - ACCESS_ONCE(t->rcu_read_lock_nesting) = nesting + 1; - - /* - * Now that we have preventing any NMIs from storing - * to the ->rcu_flipctr_idx, we can safely use it to - * remember which counter to decrement in the matching - * rcu_read_unlock(). - */ - - ACCESS_ONCE(t->rcu_flipctr_idx) = idx; - local_irq_restore(flags); - } -} -EXPORT_SYMBOL_GPL(__rcu_read_lock); - -void __rcu_read_unlock(void) -{ - int idx; - struct task_struct *t = current; - int nesting; - - nesting = ACCESS_ONCE(t->rcu_read_lock_nesting); - if (nesting > 1) { - - /* - * We are still protected by the enclosing rcu_read_lock(), - * so simply decrement the counter. - */ - - t->rcu_read_lock_nesting = nesting - 1; - - } else { - unsigned long flags; - - /* - * Disable local interrupts to prevent the grace-period - * detection state machine from seeing us half-done. - * NMIs can still occur, of course, and might themselves - * contain rcu_read_lock() and rcu_read_unlock(). - */ - - local_irq_save(flags); - - /* - * Outermost nesting of rcu_read_unlock(), so we must - * decrement the current counter for the current CPU. - * This must be done carefully, because NMIs can - * occur at any point in this code, and any rcu_read_lock() - * and rcu_read_unlock() pairs in the NMI handlers - * must interact non-destructively with this code. - * Lots of volatile casts, and -very- careful ordering. - * - * Changes to this code, including this one, must be - * inspected, validated, and tested extremely carefully!!! - */ - - /* - * First, pick up the index. - */ - - idx = ACCESS_ONCE(t->rcu_flipctr_idx); - - /* - * Now that we have fetched the counter index, it is - * safe to decrement the per-task RCU nesting counter. - * After this, any interrupts or NMIs will increment and - * decrement the per-CPU counters. - */ - ACCESS_ONCE(t->rcu_read_lock_nesting) = nesting - 1; - - /* - * It is now safe to decrement this task's nesting count. - * NMIs that occur after this statement will route their - * rcu_read_lock() calls through this "else" clause, and - * will thus start incrementing the per-CPU counter on - * their own. They will also clobber ->rcu_flipctr_idx, - * but that is OK, since we have already fetched it. - */ - - ACCESS_ONCE(RCU_DATA_ME()->rcu_flipctr[idx])--; - local_irq_restore(flags); - } -} -EXPORT_SYMBOL_GPL(__rcu_read_unlock); - -/* - * If a global counter flip has occurred since the last time that we - * advanced callbacks, advance them. Hardware interrupts must be - * disabled when calling this function. - */ -static void __rcu_advance_callbacks(struct rcu_data *rdp) -{ - int cpu; - int i; - int wlc = 0; - - if (rdp->completed != rcu_ctrlblk.completed) { - if (rdp->waitlist[GP_STAGES - 1] != NULL) { - *rdp->donetail = rdp->waitlist[GP_STAGES - 1]; - rdp->donetail = rdp->waittail[GP_STAGES - 1]; - RCU_TRACE_RDP(rcupreempt_trace_move2done, rdp); - } - for (i = GP_STAGES - 2; i >= 0; i--) { - if (rdp->waitlist[i] != NULL) { - rdp->waitlist[i + 1] = rdp->waitlist[i]; - rdp->waittail[i + 1] = rdp->waittail[i]; - wlc++; - } else { - rdp->waitlist[i + 1] = NULL; - rdp->waittail[i + 1] = - &rdp->waitlist[i + 1]; - } - } - if (rdp->nextlist != NULL) { - rdp->waitlist[0] = rdp->nextlist; - rdp->waittail[0] = rdp->nexttail; - wlc++; - rdp->nextlist = NULL; - rdp->nexttail = &rdp->nextlist; - RCU_TRACE_RDP(rcupreempt_trace_move2wait, rdp); - } else { - rdp->waitlist[0] = NULL; - rdp->waittail[0] = &rdp->waitlist[0]; - } - rdp->waitlistcount = wlc; - rdp->completed = rcu_ctrlblk.completed; - } - - /* - * Check to see if this CPU needs to report that it has seen - * the most recent counter flip, thereby declaring that all - * subsequent rcu_read_lock() invocations will respect this flip. - */ - - cpu = raw_smp_processor_id(); - if (per_cpu(rcu_flip_flag, cpu) == rcu_flipped) { - smp_mb(); /* Subsequent counter accesses must see new value */ - per_cpu(rcu_flip_flag, cpu) = rcu_flip_seen; - smp_mb(); /* Subsequent RCU read-side critical sections */ - /* seen -after- acknowledgement. */ - } -} - -#ifdef CONFIG_NO_HZ -static DEFINE_PER_CPU(int, rcu_update_flag); - -/** - * rcu_irq_enter - Called from Hard irq handlers and NMI/SMI. - * - * If the CPU was idle with dynamic ticks active, this updates the - * rcu_dyntick_sched.dynticks to let the RCU handling know that the - * CPU is active. - */ -void rcu_irq_enter(void) -{ - int cpu = smp_processor_id(); - struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu); - - if (per_cpu(rcu_update_flag, cpu)) - per_cpu(rcu_update_flag, cpu)++; - - /* - * Only update if we are coming from a stopped ticks mode - * (rcu_dyntick_sched.dynticks is even). - */ - if (!in_interrupt() && - (rdssp->dynticks & 0x1) == 0) { - /* - * The following might seem like we could have a race - * with NMI/SMIs. But this really isn't a problem. - * Here we do a read/modify/write, and the race happens - * when an NMI/SMI comes in after the read and before - * the write. But NMI/SMIs will increment this counter - * twice before returning, so the zero bit will not - * be corrupted by the NMI/SMI which is the most important - * part. - * - * The only thing is that we would bring back the counter - * to a postion that it was in during the NMI/SMI. - * But the zero bit would be set, so the rest of the - * counter would again be ignored. - * - * On return from the IRQ, the counter may have the zero - * bit be 0 and the counter the same as the return from - * the NMI/SMI. If the state machine was so unlucky to - * see that, it still doesn't matter, since all - * RCU read-side critical sections on this CPU would - * have already completed. - */ - rdssp->dynticks++; - /* - * The following memory barrier ensures that any - * rcu_read_lock() primitives in the irq handler - * are seen by other CPUs to follow the above - * increment to rcu_dyntick_sched.dynticks. This is - * required in order for other CPUs to correctly - * determine when it is safe to advance the RCU - * grace-period state machine. - */ - smp_mb(); /* see above block comment. */ - /* - * Since we can't determine the dynamic tick mode from - * the rcu_dyntick_sched.dynticks after this routine, - * we use a second flag to acknowledge that we came - * from an idle state with ticks stopped. - */ - per_cpu(rcu_update_flag, cpu)++; - /* - * If we take an NMI/SMI now, they will also increment - * the rcu_update_flag, and will not update the - * rcu_dyntick_sched.dynticks on exit. That is for - * this IRQ to do. - */ - } -} - -/** - * rcu_irq_exit - Called from exiting Hard irq context. - * - * If the CPU was idle with dynamic ticks active, update the - * rcu_dyntick_sched.dynticks to let the RCU handling be - * aware that the CPU is going back to idle with no ticks. - */ -void rcu_irq_exit(void) -{ - int cpu = smp_processor_id(); - struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu); - - /* - * rcu_update_flag is set if we interrupted the CPU - * when it was idle with ticks stopped. - * Once this occurs, we keep track of interrupt nesting - * because a NMI/SMI could also come in, and we still - * only want the IRQ that started the increment of the - * rcu_dyntick_sched.dynticks to be the one that modifies - * it on exit. - */ - if (per_cpu(rcu_update_flag, cpu)) { - if (--per_cpu(rcu_update_flag, cpu)) - return; - - /* This must match the interrupt nesting */ - WARN_ON(in_interrupt()); - - /* - * If an NMI/SMI happens now we are still - * protected by the rcu_dyntick_sched.dynticks being odd. - */ - - /* - * The following memory barrier ensures that any - * rcu_read_unlock() primitives in the irq handler - * are seen by other CPUs to preceed the following - * increment to rcu_dyntick_sched.dynticks. This - * is required in order for other CPUs to determine - * when it is safe to advance the RCU grace-period - * state machine. - */ - smp_mb(); /* see above block comment. */ - rdssp->dynticks++; - WARN_ON(rdssp->dynticks & 0x1); - } -} - -void rcu_nmi_enter(void) -{ - rcu_irq_enter(); -} - -void rcu_nmi_exit(void) -{ - rcu_irq_exit(); -} - -static void dyntick_save_progress_counter(int cpu) -{ - struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu); - - rdssp->dynticks_snap = rdssp->dynticks; -} - -static inline int -rcu_try_flip_waitack_needed(int cpu) -{ - long curr; - long snap; - struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu); - - curr = rdssp->dynticks; - snap = rdssp->dynticks_snap; - smp_mb(); /* force ordering with cpu entering/leaving dynticks. */ - - /* - * If the CPU remained in dynticks mode for the entire time - * and didn't take any interrupts, NMIs, SMIs, or whatever, - * then it cannot be in the middle of an rcu_read_lock(), so - * the next rcu_read_lock() it executes must use the new value - * of the counter. So we can safely pretend that this CPU - * already acknowledged the counter. - */ - - if ((curr == snap) && ((curr & 0x1) == 0)) - return 0; - - /* - * If the CPU passed through or entered a dynticks idle phase with - * no active irq handlers, then, as above, we can safely pretend - * that this CPU already acknowledged the counter. - */ - - if ((curr - snap) > 2 || (curr & 0x1) == 0) - return 0; - - /* We need this CPU to explicitly acknowledge the counter flip. */ - - return 1; -} - -static inline int -rcu_try_flip_waitmb_needed(int cpu) -{ - long curr; - long snap; - struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu); - - curr = rdssp->dynticks; - snap = rdssp->dynticks_snap; - smp_mb(); /* force ordering with cpu entering/leaving dynticks. */ - - /* - * If the CPU remained in dynticks mode for the entire time - * and didn't take any interrupts, NMIs, SMIs, or whatever, - * then it cannot have executed an RCU read-side critical section - * during that time, so there is no need for it to execute a - * memory barrier. - */ - - if ((curr == snap) && ((curr & 0x1) == 0)) - return 0; - - /* - * If the CPU either entered or exited an outermost interrupt, - * SMI, NMI, or whatever handler, then we know that it executed - * a memory barrier when doing so. So we don't need another one. - */ - if (curr != snap) - return 0; - - /* We need the CPU to execute a memory barrier. */ - - return 1; -} - -static void dyntick_save_progress_counter_sched(int cpu) -{ - struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu); - - rdssp->sched_dynticks_snap = rdssp->dynticks; -} - -static int rcu_qsctr_inc_needed_dyntick(int cpu) -{ - long curr; - long snap; - struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu); - - curr = rdssp->dynticks; - snap = rdssp->sched_dynticks_snap; - smp_mb(); /* force ordering with cpu entering/leaving dynticks. */ - - /* - * If the CPU remained in dynticks mode for the entire time - * and didn't take any interrupts, NMIs, SMIs, or whatever, - * then it cannot be in the middle of an rcu_read_lock(), so - * the next rcu_read_lock() it executes must use the new value - * of the counter. Therefore, this CPU has been in a quiescent - * state the entire time, and we don't need to wait for it. - */ - - if ((curr == snap) && ((curr & 0x1) == 0)) - return 0; - - /* - * If the CPU passed through or entered a dynticks idle phase with - * no active irq handlers, then, as above, this CPU has already - * passed through a quiescent state. - */ - - if ((curr - snap) > 2 || (snap & 0x1) == 0) - return 0; - - /* We need this CPU to go through a quiescent state. */ - - return 1; -} - -#else /* !CONFIG_NO_HZ */ - -# define dyntick_save_progress_counter(cpu) do { } while (0) -# define rcu_try_flip_waitack_needed(cpu) (1) -# define rcu_try_flip_waitmb_needed(cpu) (1) - -# define dyntick_save_progress_counter_sched(cpu) do { } while (0) -# define rcu_qsctr_inc_needed_dyntick(cpu) (1) - -#endif /* CONFIG_NO_HZ */ - -static void save_qsctr_sched(int cpu) -{ - struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu); - - rdssp->sched_qs_snap = rdssp->sched_qs; -} - -static inline int rcu_qsctr_inc_needed(int cpu) -{ - struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu); - - /* - * If there has been a quiescent state, no more need to wait - * on this CPU. - */ - - if (rdssp->sched_qs != rdssp->sched_qs_snap) { - smp_mb(); /* force ordering with cpu entering schedule(). */ - return 0; - } - - /* We need this CPU to go through a quiescent state. */ - - return 1; -} - -/* - * Get here when RCU is idle. Decide whether we need to - * move out of idle state, and return non-zero if so. - * "Straightforward" approach for the moment, might later - * use callback-list lengths, grace-period duration, or - * some such to determine when to exit idle state. - * Might also need a pre-idle test that does not acquire - * the lock, but let's get the simple case working first... - */ - -static int -rcu_try_flip_idle(void) -{ - int cpu; - - RCU_TRACE_ME(rcupreempt_trace_try_flip_i1); - if (!rcu_pending(smp_processor_id())) { - RCU_TRACE_ME(rcupreempt_trace_try_flip_ie1); - return 0; - } - - /* - * Do the flip. - */ - - RCU_TRACE_ME(rcupreempt_trace_try_flip_g1); - rcu_ctrlblk.completed++; /* stands in for rcu_try_flip_g2 */ - - /* - * Need a memory barrier so that other CPUs see the new - * counter value before they see the subsequent change of all - * the rcu_flip_flag instances to rcu_flipped. - */ - - smp_mb(); /* see above block comment. */ - - /* Now ask each CPU for acknowledgement of the flip. */ - - for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map)) { - per_cpu(rcu_flip_flag, cpu) = rcu_flipped; - dyntick_save_progress_counter(cpu); - } - - return 1; -} - -/* - * Wait for CPUs to acknowledge the flip. - */ - -static int -rcu_try_flip_waitack(void) -{ - int cpu; - - RCU_TRACE_ME(rcupreempt_trace_try_flip_a1); - for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map)) - if (rcu_try_flip_waitack_needed(cpu) && - per_cpu(rcu_flip_flag, cpu) != rcu_flip_seen) { - RCU_TRACE_ME(rcupreempt_trace_try_flip_ae1); - return 0; - } - - /* - * Make sure our checks above don't bleed into subsequent - * waiting for the sum of the counters to reach zero. - */ - - smp_mb(); /* see above block comment. */ - RCU_TRACE_ME(rcupreempt_trace_try_flip_a2); - return 1; -} - -/* - * Wait for collective ``last'' counter to reach zero, - * then tell all CPUs to do an end-of-grace-period memory barrier. - */ - -static int -rcu_try_flip_waitzero(void) -{ - int cpu; - int lastidx = !(rcu_ctrlblk.completed & 0x1); - int sum = 0; - - /* Check to see if the sum of the "last" counters is zero. */ - - RCU_TRACE_ME(rcupreempt_trace_try_flip_z1); - for_each_possible_cpu(cpu) - sum += RCU_DATA_CPU(cpu)->rcu_flipctr[lastidx]; - if (sum != 0) { - RCU_TRACE_ME(rcupreempt_trace_try_flip_ze1); - return 0; - } - - /* - * This ensures that the other CPUs see the call for - * memory barriers -after- the sum to zero has been - * detected here - */ - smp_mb(); /* ^^^^^^^^^^^^ */ - - /* Call for a memory barrier from each CPU. */ - for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map)) { - per_cpu(rcu_mb_flag, cpu) = rcu_mb_needed; - dyntick_save_progress_counter(cpu); - } - - RCU_TRACE_ME(rcupreempt_trace_try_flip_z2); - return 1; -} - -/* - * Wait for all CPUs to do their end-of-grace-period memory barrier. - * Return 0 once all CPUs have done so. - */ - -static int -rcu_try_flip_waitmb(void) -{ - int cpu; - - RCU_TRACE_ME(rcupreempt_trace_try_flip_m1); - for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map)) - if (rcu_try_flip_waitmb_needed(cpu) && - per_cpu(rcu_mb_flag, cpu) != rcu_mb_done) { - RCU_TRACE_ME(rcupreempt_trace_try_flip_me1); - return 0; - } - - smp_mb(); /* Ensure that the above checks precede any following flip. */ - RCU_TRACE_ME(rcupreempt_trace_try_flip_m2); - return 1; -} - -/* - * Attempt a single flip of the counters. Remember, a single flip does - * -not- constitute a grace period. Instead, the interval between - * at least GP_STAGES consecutive flips is a grace period. - * - * If anyone is nuts enough to run this CONFIG_PREEMPT_RCU implementation - * on a large SMP, they might want to use a hierarchical organization of - * the per-CPU-counter pairs. - */ -static void rcu_try_flip(void) -{ - unsigned long flags; - - RCU_TRACE_ME(rcupreempt_trace_try_flip_1); - if (unlikely(!spin_trylock_irqsave(&rcu_ctrlblk.fliplock, flags))) { - RCU_TRACE_ME(rcupreempt_trace_try_flip_e1); - return; - } - - /* - * Take the next transition(s) through the RCU grace-period - * flip-counter state machine. - */ - - switch (rcu_ctrlblk.rcu_try_flip_state) { - case rcu_try_flip_idle_state: - if (rcu_try_flip_idle()) - rcu_ctrlblk.rcu_try_flip_state = - rcu_try_flip_waitack_state; - break; - case rcu_try_flip_waitack_state: - if (rcu_try_flip_waitack()) - rcu_ctrlblk.rcu_try_flip_state = - rcu_try_flip_waitzero_state; - break; - case rcu_try_flip_waitzero_state: - if (rcu_try_flip_waitzero()) - rcu_ctrlblk.rcu_try_flip_state = - rcu_try_flip_waitmb_state; - break; - case rcu_try_flip_waitmb_state: - if (rcu_try_flip_waitmb()) - rcu_ctrlblk.rcu_try_flip_state = - rcu_try_flip_idle_state; - } - spin_unlock_irqrestore(&rcu_ctrlblk.fliplock, flags); -} - -/* - * Check to see if this CPU needs to do a memory barrier in order to - * ensure that any prior RCU read-side critical sections have committed - * their counter manipulations and critical-section memory references - * before declaring the grace period to be completed. - */ -static void rcu_check_mb(int cpu) -{ - if (per_cpu(rcu_mb_flag, cpu) == rcu_mb_needed) { - smp_mb(); /* Ensure RCU read-side accesses are visible. */ - per_cpu(rcu_mb_flag, cpu) = rcu_mb_done; - } -} - -void rcu_check_callbacks(int cpu, int user) -{ - unsigned long flags; - struct rcu_data *rdp; - - if (!rcu_pending(cpu)) - return; /* if nothing for RCU to do. */ - - /* - * If this CPU took its interrupt from user mode or from the - * idle loop, and this is not a nested interrupt, then - * this CPU has to have exited all prior preept-disable - * sections of code. So invoke rcu_sched_qs() to note this. - * - * The memory barrier is needed to handle the case where - * writes from a preempt-disable section of code get reordered - * into schedule() by this CPU's write buffer. So the memory - * barrier makes sure that the rcu_sched_qs() is seen by other - * CPUs to happen after any such write. - */ - - rdp = RCU_DATA_CPU(cpu); - if (user || - (idle_cpu(cpu) && !in_softirq() && - hardirq_count() <= (1 << HARDIRQ_SHIFT))) { - smp_mb(); /* Guard against aggressive schedule(). */ - rcu_sched_qs(cpu); - } - - rcu_check_mb(cpu); - if (rcu_ctrlblk.completed == rdp->completed) - rcu_try_flip(); - spin_lock_irqsave(&rdp->lock, flags); - RCU_TRACE_RDP(rcupreempt_trace_check_callbacks, rdp); - __rcu_advance_callbacks(rdp); - if (rdp->donelist == NULL) { - spin_unlock_irqrestore(&rdp->lock, flags); - } else { - spin_unlock_irqrestore(&rdp->lock, flags); - raise_softirq(RCU_SOFTIRQ); - } -} - -/* - * Needed by dynticks, to make sure all RCU processing has finished - * when we go idle: - */ -void rcu_advance_callbacks(int cpu, int user) -{ - unsigned long flags; - struct rcu_data *rdp = RCU_DATA_CPU(cpu); - - if (rcu_ctrlblk.completed == rdp->completed) { - rcu_try_flip(); - if (rcu_ctrlblk.completed == rdp->completed) - return; - } - spin_lock_irqsave(&rdp->lock, flags); - RCU_TRACE_RDP(rcupreempt_trace_check_callbacks, rdp); - __rcu_advance_callbacks(rdp); - spin_unlock_irqrestore(&rdp->lock, flags); -} - -#ifdef CONFIG_HOTPLUG_CPU -#define rcu_offline_cpu_enqueue(srclist, srctail, dstlist, dsttail) do { \ - *dsttail = srclist; \ - if (srclist != NULL) { \ - dsttail = srctail; \ - srclist = NULL; \ - srctail = &srclist;\ - } \ - } while (0) - -void rcu_offline_cpu(int cpu) -{ - int i; - struct rcu_head *list = NULL; - unsigned long flags; - struct rcu_data *rdp = RCU_DATA_CPU(cpu); - struct rcu_head *schedlist = NULL; - struct rcu_head **schedtail = &schedlist; - struct rcu_head **tail = &list; - - /* - * Remove all callbacks from the newly dead CPU, retaining order. - * Otherwise rcu_barrier() will fail - */ - - spin_lock_irqsave(&rdp->lock, flags); - rcu_offline_cpu_enqueue(rdp->donelist, rdp->donetail, list, tail); - for (i = GP_STAGES - 1; i >= 0; i--) - rcu_offline_cpu_enqueue(rdp->waitlist[i], rdp->waittail[i], - list, tail); - rcu_offline_cpu_enqueue(rdp->nextlist, rdp->nexttail, list, tail); - rcu_offline_cpu_enqueue(rdp->waitschedlist, rdp->waitschedtail, - schedlist, schedtail); - rcu_offline_cpu_enqueue(rdp->nextschedlist, rdp->nextschedtail, - schedlist, schedtail); - rdp->rcu_sched_sleeping = 0; - spin_unlock_irqrestore(&rdp->lock, flags); - rdp->waitlistcount = 0; - - /* Disengage the newly dead CPU from the grace-period computation. */ - - spin_lock_irqsave(&rcu_ctrlblk.fliplock, flags); - rcu_check_mb(cpu); - if (per_cpu(rcu_flip_flag, cpu) == rcu_flipped) { - smp_mb(); /* Subsequent counter accesses must see new value */ - per_cpu(rcu_flip_flag, cpu) = rcu_flip_seen; - smp_mb(); /* Subsequent RCU read-side critical sections */ - /* seen -after- acknowledgement. */ - } - - cpumask_clear_cpu(cpu, to_cpumask(rcu_cpu_online_map)); - - spin_unlock_irqrestore(&rcu_ctrlblk.fliplock, flags); - - /* - * Place the removed callbacks on the current CPU's queue. - * Make them all start a new grace period: simple approach, - * in theory could starve a given set of callbacks, but - * you would need to be doing some serious CPU hotplugging - * to make this happen. If this becomes a problem, adding - * a synchronize_rcu() to the hotplug path would be a simple - * fix. - */ - - local_irq_save(flags); /* disable preempt till we know what lock. */ - rdp = RCU_DATA_ME(); - spin_lock(&rdp->lock); - *rdp->nexttail = list; - if (list) - rdp->nexttail = tail; - *rdp->nextschedtail = schedlist; - if (schedlist) - rdp->nextschedtail = schedtail; - spin_unlock_irqrestore(&rdp->lock, flags); -} - -#else /* #ifdef CONFIG_HOTPLUG_CPU */ - -void rcu_offline_cpu(int cpu) -{ -} - -#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ - -void __cpuinit rcu_online_cpu(int cpu) -{ - unsigned long flags; - struct rcu_data *rdp; - - spin_lock_irqsave(&rcu_ctrlblk.fliplock, flags); - cpumask_set_cpu(cpu, to_cpumask(rcu_cpu_online_map)); - spin_unlock_irqrestore(&rcu_ctrlblk.fliplock, flags); - - /* - * The rcu_sched grace-period processing might have bypassed - * this CPU, given that it was not in the rcu_cpu_online_map - * when the grace-period scan started. This means that the - * grace-period task might sleep. So make sure that if this - * should happen, the first callback posted to this CPU will - * wake up the grace-period task if need be. - */ - - rdp = RCU_DATA_CPU(cpu); - spin_lock_irqsave(&rdp->lock, flags); - rdp->rcu_sched_sleeping = 1; - spin_unlock_irqrestore(&rdp->lock, flags); -} - -static void rcu_process_callbacks(struct softirq_action *unused) -{ - unsigned long flags; - struct rcu_head *next, *list; - struct rcu_data *rdp; - - local_irq_save(flags); - rdp = RCU_DATA_ME(); - spin_lock(&rdp->lock); - list = rdp->donelist; - if (list == NULL) { - spin_unlock_irqrestore(&rdp->lock, flags); - return; - } - rdp->donelist = NULL; - rdp->donetail = &rdp->donelist; - RCU_TRACE_RDP(rcupreempt_trace_done_remove, rdp); - spin_unlock_irqrestore(&rdp->lock, flags); - while (list) { - next = list->next; - list->func(list); - list = next; - RCU_TRACE_ME(rcupreempt_trace_invoke); - } -} - -void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) -{ - unsigned long flags; - struct rcu_data *rdp; - - head->func = func; - head->next = NULL; - local_irq_save(flags); - rdp = RCU_DATA_ME(); - spin_lock(&rdp->lock); - __rcu_advance_callbacks(rdp); - *rdp->nexttail = head; - rdp->nexttail = &head->next; - RCU_TRACE_RDP(rcupreempt_trace_next_add, rdp); - spin_unlock_irqrestore(&rdp->lock, flags); -} -EXPORT_SYMBOL_GPL(call_rcu); - -void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) -{ - unsigned long flags; - struct rcu_data *rdp; - int wake_gp = 0; - - head->func = func; - head->next = NULL; - local_irq_save(flags); - rdp = RCU_DATA_ME(); - spin_lock(&rdp->lock); - *rdp->nextschedtail = head; - rdp->nextschedtail = &head->next; - if (rdp->rcu_sched_sleeping) { - - /* Grace-period processing might be sleeping... */ - - rdp->rcu_sched_sleeping = 0; - wake_gp = 1; - } - spin_unlock_irqrestore(&rdp->lock, flags); - if (wake_gp) { - - /* Wake up grace-period processing, unless someone beat us. */ - - spin_lock_irqsave(&rcu_ctrlblk.schedlock, flags); - if (rcu_ctrlblk.sched_sleep != rcu_sched_sleeping) - wake_gp = 0; - rcu_ctrlblk.sched_sleep = rcu_sched_not_sleeping; - spin_unlock_irqrestore(&rcu_ctrlblk.schedlock, flags); - if (wake_gp) - wake_up_interruptible(&rcu_ctrlblk.sched_wq); - } -} -EXPORT_SYMBOL_GPL(call_rcu_sched); - -/* - * Wait until all currently running preempt_disable() code segments - * (including hardware-irq-disable segments) complete. Note that - * in -rt this does -not- necessarily result in all currently executing - * interrupt -handlers- having completed. - */ -void __synchronize_sched(void) -{ - struct rcu_synchronize rcu; - - if (num_online_cpus() == 1) - return; /* blocking is gp if only one CPU! */ - - init_completion(&rcu.completion); - /* Will wake me after RCU finished. */ - call_rcu_sched(&rcu.head, wakeme_after_rcu); - /* Wait for it. */ - wait_for_completion(&rcu.completion); -} -EXPORT_SYMBOL_GPL(__synchronize_sched); - -/* - * kthread function that manages call_rcu_sched grace periods. - */ -static int rcu_sched_grace_period(void *arg) -{ - int couldsleep; /* might sleep after current pass. */ - int couldsleepnext = 0; /* might sleep after next pass. */ - int cpu; - unsigned long flags; - struct rcu_data *rdp; - int ret; - - /* - * Each pass through the following loop handles one - * rcu_sched grace period cycle. - */ - do { - /* Save each CPU's current state. */ - - for_each_online_cpu(cpu) { - dyntick_save_progress_counter_sched(cpu); - save_qsctr_sched(cpu); - } - - /* - * Sleep for about an RCU grace-period's worth to - * allow better batching and to consume less CPU. - */ - schedule_timeout_interruptible(RCU_SCHED_BATCH_TIME); - - /* - * If there was nothing to do last time, prepare to - * sleep at the end of the current grace period cycle. - */ - couldsleep = couldsleepnext; - couldsleepnext = 1; - if (couldsleep) { - spin_lock_irqsave(&rcu_ctrlblk.schedlock, flags); - rcu_ctrlblk.sched_sleep = rcu_sched_sleep_prep; - spin_unlock_irqrestore(&rcu_ctrlblk.schedlock, flags); - } - - /* - * Wait on each CPU in turn to have either visited - * a quiescent state or been in dynticks-idle mode. - */ - for_each_online_cpu(cpu) { - while (rcu_qsctr_inc_needed(cpu) && - rcu_qsctr_inc_needed_dyntick(cpu)) { - /* resched_cpu(cpu); @@@ */ - schedule_timeout_interruptible(1); - } - } - - /* Advance callbacks for each CPU. */ - - for_each_online_cpu(cpu) { - - rdp = RCU_DATA_CPU(cpu); - spin_lock_irqsave(&rdp->lock, flags); - - /* - * We are running on this CPU irq-disabled, so no - * CPU can go offline until we re-enable irqs. - * The current CPU might have already gone - * offline (between the for_each_offline_cpu and - * the spin_lock_irqsave), but in that case all its - * callback lists will be empty, so no harm done. - * - * Advance the callbacks! We share normal RCU's - * donelist, since callbacks are invoked the - * same way in either case. - */ - if (rdp->waitschedlist != NULL) { - *rdp->donetail = rdp->waitschedlist; - rdp->donetail = rdp->waitschedtail; - - /* - * Next rcu_check_callbacks() will - * do the required raise_softirq(). - */ - } - if (rdp->nextschedlist != NULL) { - rdp->waitschedlist = rdp->nextschedlist; - rdp->waitschedtail = rdp->nextschedtail; - couldsleep = 0; - couldsleepnext = 0; - } else { - rdp->waitschedlist = NULL; - rdp->waitschedtail = &rdp->waitschedlist; - } - rdp->nextschedlist = NULL; - rdp->nextschedtail = &rdp->nextschedlist; - - /* Mark sleep intention. */ - - rdp->rcu_sched_sleeping = couldsleep; - - spin_unlock_irqrestore(&rdp->lock, flags); - } - - /* If we saw callbacks on the last scan, go deal with them. */ - - if (!couldsleep) - continue; - - /* Attempt to block... */ - - spin_lock_irqsave(&rcu_ctrlblk.schedlock, flags); - if (rcu_ctrlblk.sched_sleep != rcu_sched_sleep_prep) { - - /* - * Someone posted a callback after we scanned. - * Go take care of it. - */ - spin_unlock_irqrestore(&rcu_ctrlblk.schedlock, flags); - couldsleepnext = 0; - continue; - } - - /* Block until the next person posts a callback. */ - - rcu_ctrlblk.sched_sleep = rcu_sched_sleeping; - spin_unlock_irqrestore(&rcu_ctrlblk.schedlock, flags); - ret = 0; /* unused */ - __wait_event_interruptible(rcu_ctrlblk.sched_wq, - rcu_ctrlblk.sched_sleep != rcu_sched_sleeping, - ret); - - couldsleepnext = 0; - - } while (!kthread_should_stop()); - - return (0); -} - -/* - * Check to see if any future RCU-related work will need to be done - * by the current CPU, even if none need be done immediately, returning - * 1 if so. Assumes that notifiers would take care of handling any - * outstanding requests from the RCU core. - * - * This function is part of the RCU implementation; it is -not- - * an exported member of the RCU API. - */ -int rcu_needs_cpu(int cpu) -{ - struct rcu_data *rdp = RCU_DATA_CPU(cpu); - - return (rdp->donelist != NULL || - !!rdp->waitlistcount || - rdp->nextlist != NULL || - rdp->nextschedlist != NULL || - rdp->waitschedlist != NULL); -} - -static int rcu_pending(int cpu) -{ - struct rcu_data *rdp = RCU_DATA_CPU(cpu); - - /* The CPU has at least one callback queued somewhere. */ - - if (rdp->donelist != NULL || - !!rdp->waitlistcount || - rdp->nextlist != NULL || - rdp->nextschedlist != NULL || - rdp->waitschedlist != NULL) - return 1; - - /* The RCU core needs an acknowledgement from this CPU. */ - - if ((per_cpu(rcu_flip_flag, cpu) == rcu_flipped) || - (per_cpu(rcu_mb_flag, cpu) == rcu_mb_needed)) - return 1; - - /* This CPU has fallen behind the global grace-period number. */ - - if (rdp->completed != rcu_ctrlblk.completed) - return 1; - - /* Nothing needed from this CPU. */ - - return 0; -} - -int __cpuinit rcu_cpu_notify(struct notifier_block *self, - unsigned long action, void *hcpu) -{ - long cpu = (long)hcpu; - - switch (action) { - case CPU_UP_PREPARE: - case CPU_UP_PREPARE_FROZEN: - rcu_online_cpu(cpu); - break; - case CPU_UP_CANCELED: - case CPU_UP_CANCELED_FROZEN: - case CPU_DEAD: - case CPU_DEAD_FROZEN: - rcu_offline_cpu(cpu); - break; - default: - break; - } - return NOTIFY_OK; -} - -void __init __rcu_init(void) -{ - int cpu; - int i; - struct rcu_data *rdp; - - printk(KERN_NOTICE "Preemptible RCU implementation.\n"); - for_each_possible_cpu(cpu) { - rdp = RCU_DATA_CPU(cpu); - spin_lock_init(&rdp->lock); - rdp->completed = 0; - rdp->waitlistcount = 0; - rdp->nextlist = NULL; - rdp->nexttail = &rdp->nextlist; - for (i = 0; i < GP_STAGES; i++) { - rdp->waitlist[i] = NULL; - rdp->waittail[i] = &rdp->waitlist[i]; - } - rdp->donelist = NULL; - rdp->donetail = &rdp->donelist; - rdp->rcu_flipctr[0] = 0; - rdp->rcu_flipctr[1] = 0; - rdp->nextschedlist = NULL; - rdp->nextschedtail = &rdp->nextschedlist; - rdp->waitschedlist = NULL; - rdp->waitschedtail = &rdp->waitschedlist; - rdp->rcu_sched_sleeping = 0; - } - open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); -} - -/* - * Late-boot-time RCU initialization that must wait until after scheduler - * has been initialized. - */ -void __init rcu_init_sched(void) -{ - rcu_sched_grace_period_task = kthread_run(rcu_sched_grace_period, - NULL, - "rcu_sched_grace_period"); - WARN_ON(IS_ERR(rcu_sched_grace_period_task)); -} - -#ifdef CONFIG_RCU_TRACE -long *rcupreempt_flipctr(int cpu) -{ - return &RCU_DATA_CPU(cpu)->rcu_flipctr[0]; -} -EXPORT_SYMBOL_GPL(rcupreempt_flipctr); - -int rcupreempt_flip_flag(int cpu) -{ - return per_cpu(rcu_flip_flag, cpu); -} -EXPORT_SYMBOL_GPL(rcupreempt_flip_flag); - -int rcupreempt_mb_flag(int cpu) -{ - return per_cpu(rcu_mb_flag, cpu); -} -EXPORT_SYMBOL_GPL(rcupreempt_mb_flag); - -char *rcupreempt_try_flip_state_name(void) -{ - return rcu_try_flip_state_names[rcu_ctrlblk.rcu_try_flip_state]; -} -EXPORT_SYMBOL_GPL(rcupreempt_try_flip_state_name); - -struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu) -{ - struct rcu_data *rdp = RCU_DATA_CPU(cpu); - - return &rdp->trace; -} -EXPORT_SYMBOL_GPL(rcupreempt_trace_cpu); - -#endif /* #ifdef RCU_TRACE */ diff --git a/kernel/rcupreempt_trace.c b/kernel/rcupreempt_trace.c deleted file mode 100644 index 11640346a507..000000000000 --- a/kernel/rcupreempt_trace.c +++ /dev/null @@ -1,335 +0,0 @@ -/* - * Read-Copy Update tracing for realtime implementation - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. - * - * Copyright IBM Corporation, 2006 - * - * Papers: http://www.rdrop.com/users/paulmck/RCU - * - * For detailed explanation of Read-Copy Update mechanism see - - * Documentation/RCU/ *.txt - * - */ -#include <linux/types.h> -#include <linux/kernel.h> -#include <linux/init.h> -#include <linux/spinlock.h> -#include <linux/smp.h> -#include <linux/rcupdate.h> -#include <linux/interrupt.h> -#include <linux/sched.h> -#include <asm/atomic.h> -#include <linux/bitops.h> -#include <linux/module.h> -#include <linux/completion.h> -#include <linux/moduleparam.h> -#include <linux/percpu.h> -#include <linux/notifier.h> -#include <linux/cpu.h> -#include <linux/mutex.h> -#include <linux/rcupreempt_trace.h> -#include <linux/debugfs.h> - -static struct mutex rcupreempt_trace_mutex; -static char *rcupreempt_trace_buf; -#define RCUPREEMPT_TRACE_BUF_SIZE 4096 - -void rcupreempt_trace_move2done(struct rcupreempt_trace *trace) -{ - trace->done_length += trace->wait_length; - trace->done_add += trace->wait_length; - trace->wait_length = 0; -} -void rcupreempt_trace_move2wait(struct rcupreempt_trace *trace) -{ - trace->wait_length += trace->next_length; - trace->wait_add += trace->next_length; - trace->next_length = 0; -} -void rcupreempt_trace_try_flip_1(struct rcupreempt_trace *trace) -{ - atomic_inc(&trace->rcu_try_flip_1); -} -void rcupreempt_trace_try_flip_e1(struct rcupreempt_trace *trace) -{ - atomic_inc(&trace->rcu_try_flip_e1); -} -void rcupreempt_trace_try_flip_i1(struct rcupreempt_trace *trace) -{ - trace->rcu_try_flip_i1++; -} -void rcupreempt_trace_try_flip_ie1(struct rcupreempt_trace *trace) -{ - trace->rcu_try_flip_ie1++; -} -void rcupreempt_trace_try_flip_g1(struct rcupreempt_trace *trace) -{ - trace->rcu_try_flip_g1++; -} -void rcupreempt_trace_try_flip_a1(struct rcupreempt_trace *trace) -{ - trace->rcu_try_flip_a1++; -} -void rcupreempt_trace_try_flip_ae1(struct rcupreempt_trace *trace) -{ - trace->rcu_try_flip_ae1++; -} -void rcupreempt_trace_try_flip_a2(struct rcupreempt_trace *trace) -{ - trace->rcu_try_flip_a2++; -} -void rcupreempt_trace_try_flip_z1(struct rcupreempt_trace *trace) -{ - trace->rcu_try_flip_z1++; -} -void rcupreempt_trace_try_flip_ze1(struct rcupreempt_trace *trace) -{ - trace->rcu_try_flip_ze1++; -} -void rcupreempt_trace_try_flip_z2(struct rcupreempt_trace *trace) -{ - trace->rcu_try_flip_z2++; -} -void rcupreempt_trace_try_flip_m1(struct rcupreempt_trace *trace) -{ - trace->rcu_try_flip_m1++; -} -void rcupreempt_trace_try_flip_me1(struct rcupreempt_trace *trace) -{ - trace->rcu_try_flip_me1++; -} -void rcupreempt_trace_try_flip_m2(struct rcupreempt_trace *trace) -{ - trace->rcu_try_flip_m2++; -} -void rcupreempt_trace_check_callbacks(struct rcupreempt_trace *trace) -{ - trace->rcu_check_callbacks++; -} -void rcupreempt_trace_done_remove(struct rcupreempt_trace *trace) -{ - trace->done_remove += trace->done_length; - trace->done_length = 0; -} -void rcupreempt_trace_invoke(struct rcupreempt_trace *trace) -{ - atomic_inc(&trace->done_invoked); -} -void rcupreempt_trace_next_add(struct rcupreempt_trace *trace) -{ - trace->next_add++; - trace->next_length++; -} - -static void rcupreempt_trace_sum(struct rcupreempt_trace *sp) -{ - struct rcupreempt_trace *cp; - int cpu; - - memset(sp, 0, sizeof(*sp)); - for_each_possible_cpu(cpu) { - cp = rcupreempt_trace_cpu(cpu); - sp->next_length += cp->next_length; - sp->next_add += cp->next_add; - sp->wait_length += cp->wait_length; - sp->wait_add += cp->wait_add; - sp->done_length += cp->done_length; - sp->done_add += cp->done_add; - sp->done_remove += cp->done_remove; - atomic_add(atomic_read(&cp->done_invoked), &sp->done_invoked); - sp->rcu_check_callbacks += cp->rcu_check_callbacks; - atomic_add(atomic_read(&cp->rcu_try_flip_1), - &sp->rcu_try_flip_1); - atomic_add(atomic_read(&cp->rcu_try_flip_e1), - &sp->rcu_try_flip_e1); - sp->rcu_try_flip_i1 += cp->rcu_try_flip_i1; - sp->rcu_try_flip_ie1 += cp->rcu_try_flip_ie1; - sp->rcu_try_flip_g1 += cp->rcu_try_flip_g1; - sp->rcu_try_flip_a1 += cp->rcu_try_flip_a1; - sp->rcu_try_flip_ae1 += cp->rcu_try_flip_ae1; - sp->rcu_try_flip_a2 += cp->rcu_try_flip_a2; - sp->rcu_try_flip_z1 += cp->rcu_try_flip_z1; - sp->rcu_try_flip_ze1 += cp->rcu_try_flip_ze1; - sp->rcu_try_flip_z2 += cp->rcu_try_flip_z2; - sp->rcu_try_flip_m1 += cp->rcu_try_flip_m1; - sp->rcu_try_flip_me1 += cp->rcu_try_flip_me1; - sp->rcu_try_flip_m2 += cp->rcu_try_flip_m2; - } -} - -static ssize_t rcustats_read(struct file *filp, char __user *buffer, - size_t count, loff_t *ppos) -{ - struct rcupreempt_trace trace; - ssize_t bcount; - int cnt = 0; - - rcupreempt_trace_sum(&trace); - mutex_lock(&rcupreempt_trace_mutex); - snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE - cnt, - "ggp=%ld rcc=%ld\n", - rcu_batches_completed(), - trace.rcu_check_callbacks); - snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE - cnt, - "na=%ld nl=%ld wa=%ld wl=%ld da=%ld dl=%ld dr=%ld di=%d\n" - "1=%d e1=%d i1=%ld ie1=%ld g1=%ld a1=%ld ae1=%ld a2=%ld\n" - "z1=%ld ze1=%ld z2=%ld m1=%ld me1=%ld m2=%ld\n", - - trace.next_add, trace.next_length, - trace.wait_add, trace.wait_length, - trace.done_add, trace.done_length, - trace.done_remove, atomic_read(&trace.done_invoked), - atomic_read(&trace.rcu_try_flip_1), - atomic_read(&trace.rcu_try_flip_e1), - trace.rcu_try_flip_i1, trace.rcu_try_flip_ie1, - trace.rcu_try_flip_g1, - trace.rcu_try_flip_a1, trace.rcu_try_flip_ae1, - trace.rcu_try_flip_a2, - trace.rcu_try_flip_z1, trace.rcu_try_flip_ze1, - trace.rcu_try_flip_z2, - trace.rcu_try_flip_m1, trace.rcu_try_flip_me1, - trace.rcu_try_flip_m2); - bcount = simple_read_from_buffer(buffer, count, ppos, - rcupreempt_trace_buf, strlen(rcupreempt_trace_buf)); - mutex_unlock(&rcupreempt_trace_mutex); - return bcount; -} - -static ssize_t rcugp_read(struct file *filp, char __user *buffer, - size_t count, loff_t *ppos) -{ - long oldgp = rcu_batches_completed(); - ssize_t bcount; - - mutex_lock(&rcupreempt_trace_mutex); - synchronize_rcu(); - snprintf(rcupreempt_trace_buf, RCUPREEMPT_TRACE_BUF_SIZE, - "oldggp=%ld newggp=%ld\n", oldgp, rcu_batches_completed()); - bcount = simple_read_from_buffer(buffer, count, ppos, - rcupreempt_trace_buf, strlen(rcupreempt_trace_buf)); - mutex_unlock(&rcupreempt_trace_mutex); - return bcount; -} - -static ssize_t rcuctrs_read(struct file *filp, char __user *buffer, - size_t count, loff_t *ppos) -{ - int cnt = 0; - int cpu; - int f = rcu_batches_completed() & 0x1; - ssize_t bcount; - - mutex_lock(&rcupreempt_trace_mutex); - - cnt += snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE, - "CPU last cur F M\n"); - for_each_possible_cpu(cpu) { - long *flipctr = rcupreempt_flipctr(cpu); - cnt += snprintf(&rcupreempt_trace_buf[cnt], - RCUPREEMPT_TRACE_BUF_SIZE - cnt, - "%3d%c %4ld %3ld %d %d\n", - cpu, - cpu_is_offline(cpu) ? '!' : ' ', - flipctr[!f], - flipctr[f], - rcupreempt_flip_flag(cpu), - rcupreempt_mb_flag(cpu)); - } - cnt += snprintf(&rcupreempt_trace_buf[cnt], - RCUPREEMPT_TRACE_BUF_SIZE - cnt, - "ggp = %ld, state = %s\n", - rcu_batches_completed(), - rcupreempt_try_flip_state_name()); - cnt += snprintf(&rcupreempt_trace_buf[cnt], - RCUPREEMPT_TRACE_BUF_SIZE - cnt, - "\n"); - bcount = simple_read_from_buffer(buffer, count, ppos, - rcupreempt_trace_buf, strlen(rcupreempt_trace_buf)); - mutex_unlock(&rcupreempt_trace_mutex); - return bcount; -} - -static struct file_operations rcustats_fops = { - .owner = THIS_MODULE, - .read = rcustats_read, -}; - -static struct file_operations rcugp_fops = { - .owner = THIS_MODULE, - .read = rcugp_read, -}; - -static struct file_operations rcuctrs_fops = { - .owner = THIS_MODULE, - .read = rcuctrs_read, -}; - -static struct dentry *rcudir, *statdir, *ctrsdir, *gpdir; -static int rcupreempt_debugfs_init(void) -{ - rcudir = debugfs_create_dir("rcu", NULL); - if (!rcudir) - goto out; - statdir = debugfs_create_file("rcustats", 0444, rcudir, - NULL, &rcustats_fops); - if (!statdir) - goto free_out; - - gpdir = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops); - if (!gpdir) - goto free_out; - - ctrsdir = debugfs_create_file("rcuctrs", 0444, rcudir, - NULL, &rcuctrs_fops); - if (!ctrsdir) - goto free_out; - return 0; -free_out: - if (statdir) - debugfs_remove(statdir); - if (gpdir) - debugfs_remove(gpdir); - debugfs_remove(rcudir); -out: - return 1; -} - -static int __init rcupreempt_trace_init(void) -{ - int ret; - - mutex_init(&rcupreempt_trace_mutex); - rcupreempt_trace_buf = kmalloc(RCUPREEMPT_TRACE_BUF_SIZE, GFP_KERNEL); - if (!rcupreempt_trace_buf) - return 1; - ret = rcupreempt_debugfs_init(); - if (ret) - kfree(rcupreempt_trace_buf); - return ret; -} - -static void __exit rcupreempt_trace_cleanup(void) -{ - debugfs_remove(statdir); - debugfs_remove(gpdir); - debugfs_remove(ctrsdir); - debugfs_remove(rcudir); - kfree(rcupreempt_trace_buf); -} - - -module_init(rcupreempt_trace_init); -module_exit(rcupreempt_trace_cleanup); diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index f87fb0c8f924..82fbc49728df 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -725,7 +725,7 @@ config RCU_TORTURE_TEST_RUNNABLE config RCU_CPU_STALL_DETECTOR bool "Check for stalled CPUs delaying RCU grace periods" - depends on CLASSIC_RCU || TREE_RCU || TREE_PREEMPT_RCU + depends on TREE_RCU || TREE_PREEMPT_RCU default n help This option causes RCU to printk information on which |
