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Diffstat (limited to 'include/linux/srcutiny.h')
| -rw-r--r-- | include/linux/srcutiny.h | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h new file mode 100644 index 000000000000..cfbfc540cafc --- /dev/null +++ b/include/linux/srcutiny.h @@ -0,0 +1,90 @@ +/* + * Sleepable Read-Copy Update mechanism for mutual exclusion, + * tiny variant. + * + * 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, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. + * + * Copyright (C) IBM Corporation, 2017 + * + * Author: Paul McKenney <paulmck@us.ibm.com> + */ + +#ifndef _LINUX_SRCU_TINY_H +#define _LINUX_SRCU_TINY_H + +#include <linux/swait.h> + +struct srcu_struct { + short srcu_lock_nesting[2]; /* srcu_read_lock() nesting depth. */ + short srcu_idx; /* Current reader array element. */ + u8 srcu_gp_running; /* GP workqueue running? */ + u8 srcu_gp_waiting; /* GP waiting for readers? */ + struct swait_queue_head srcu_wq; + /* Last srcu_read_unlock() wakes GP. */ + struct rcu_head *srcu_cb_head; /* Pending callbacks: Head. */ + struct rcu_head **srcu_cb_tail; /* Pending callbacks: Tail. */ + struct work_struct srcu_work; /* For driving grace periods. */ +#ifdef CONFIG_DEBUG_LOCK_ALLOC + struct lockdep_map dep_map; +#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ +}; + +void srcu_drive_gp(struct work_struct *wp); + +#define __SRCU_STRUCT_INIT(name) \ +{ \ + .srcu_wq = __SWAIT_QUEUE_HEAD_INITIALIZER(name.srcu_wq), \ + .srcu_cb_tail = &name.srcu_cb_head, \ + .srcu_work = __WORK_INITIALIZER(name.srcu_work, srcu_drive_gp), \ + __SRCU_DEP_MAP_INIT(name) \ +} + +/* + * This odd _STATIC_ arrangement is needed for API compatibility with + * Tree SRCU, which needs some per-CPU data. + */ +#define DEFINE_SRCU(name) \ + struct srcu_struct name = __SRCU_STRUCT_INIT(name) +#define DEFINE_STATIC_SRCU(name) \ + static struct srcu_struct name = __SRCU_STRUCT_INIT(name) + +void synchronize_srcu(struct srcu_struct *sp); + +/* + * Counts the new reader in the appropriate per-CPU element of the + * srcu_struct. Can be invoked from irq/bh handlers, but the matching + * __srcu_read_unlock() must be in the same handler instance. Returns an + * index that must be passed to the matching srcu_read_unlock(). + */ +static inline int __srcu_read_lock(struct srcu_struct *sp) +{ + int idx; + + idx = READ_ONCE(sp->srcu_idx); + WRITE_ONCE(sp->srcu_lock_nesting[idx], sp->srcu_lock_nesting[idx] + 1); + return idx; +} + +static inline void synchronize_srcu_expedited(struct srcu_struct *sp) +{ + synchronize_srcu(sp); +} + +static inline void srcu_barrier(struct srcu_struct *sp) +{ + synchronize_srcu(sp); +} + +#endif |
