talos-obmc-linux/include/linux/lockdep.h, branch v2.6.26-rc6

workqueue: debug flushing deadlocks with lockdep

2007-10-19T18:53:38+00:00

In the following scenario: code path 1: my_function() -> lock(L1); ...; flush_workqueue(); ... code path 2: run_workqueue() -> my_work() -> ...; lock(L1); ... you can get a deadlock when my_work() is queued or running but my_function() has acquired L1 already. This patch adds a pseudo-lock to each workqueue to make lockdep warn about this scenario. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Johannes Berg Acked-by: Oleg Nesterov Acked-by: Ingo Molnar Acked-by: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lockdep: annotate rcu_read_{,un}lock{,_bh}

2007-10-11T20:11:12+00:00

lockdep annotate rcu_read_{,un}lock{,_bh} in order to catch imbalanced usage. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar Cc: Paul E. McKenney

lockdep: syscall exit check

2007-10-11T20:11:12+00:00

Provide a check to validate that we do not hold any locks when switching back to user-space. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar

lockstat: measure lock bouncing

2007-07-19T17:04:49+00:00

__acquire | lock _____ | \ | __contended | | | wait | _______/ |/ | __acquired | __release | unlock We measure acquisition and contention bouncing. This is done by recording a cpu stamp in each lock instance. Contention bouncing requires the cpu stamp to be set on acquisition. Hence we move __acquired into the generic path. __acquired is then used to measure acquisition bouncing by comparing the current cpu with the old stamp before replacing it. __contended is used to measure contention bouncing (only useful for preemptable locks) [akpm@linux-foundation.org: cleanups] Signed-off-by: Peter Zijlstra Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lockdep: various fixes

2007-07-19T17:04:49+00:00

- update the copyright notices - use the default hash function - fix a thinko in a BUILD_BUG_ON - add a WARN_ON to spot inconsitent naming - fix a termination issue in /proc/lock_stat [akpm@linux-foundation.org: cleanups] Signed-off-by: Peter Zijlstra Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lockstat: core infrastructure

2007-07-19T17:04:49+00:00

Introduce the core lock statistics code. Lock statistics provides lock wait-time and hold-time (as well as the count of corresponding contention and acquisitions events). Also, the first few call-sites that encounter contention are tracked. Lock wait-time is the time spent waiting on the lock. This provides insight into the locking scheme, that is, a heavily contended lock is indicative of a too coarse locking scheme. Lock hold-time is the duration the lock was held, this provides a reference for the wait-time numbers, so they can be put into perspective. 1) lock 2) ... do stuff .. unlock 3) The time between 1 and 2 is the wait-time. The time between 2 and 3 is the hold-time. The lockdep held-lock tracking code is reused, because it already collects locks into meaningful groups (classes), and because it is an existing infrastructure for lock instrumentation. Currently lockdep tracks lock acquisition with two hooks: lock() lock_acquire() _lock() ... code protected by lock ... unlock() lock_release() _unlock() We need to extend this with two more hooks, in order to measure contention. lock_contended() - used to measure contention events lock_acquired() - completion of the contention These are then placed the following way: lock() lock_acquire() if (!_try_lock()) lock_contended() _lock() lock_acquired() ... do locked stuff ... unlock() lock_release() _unlock() (Note: the try_lock() 'trick' is used to avoid instrumenting all platform dependent lock primitive implementations.) It is also possible to toggle the two lockdep features at runtime using: /proc/sys/kernel/prove_locking /proc/sys/kernel/lock_stat (esp. turning off the O(n^2) prove_locking functionaliy can help) [akpm@linux-foundation.org: build fixes] [akpm@linux-foundation.org: nuke unneeded ifdefs] Signed-off-by: Peter Zijlstra Acked-by: Ingo Molnar Acked-by: Jason Baron Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] lockdep: lockdep_depth vs. debug_locks

2007-03-23T02:39:06+00:00

lockdep found a bug during a run of workqueue function - this could be also caused by a bug from other code running simultaneously. lockdep really shouldn't be used when debug_locks == 0! Reported-by: Folkert van Heusden Inspired-by: Oleg Nesterov Signed-off-by: Jarek Poplawski Cc: Ingo Molnar Acked-by: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] lockdep: forward declare struct task_struct

2007-02-12T17:48:29+00:00

3117df0453828bd045c16244e6f50e5714667a8a causes this: In file included from arch/s390/kernel/early.c:13: include/linux/lockdep.h:300: warning: "struct task_struct" declared inside parameter list include/linux/lockdep.h:300: warning: its scope is only this definition or declaration, which is probably not what you want Acked-by: Ingo Molnar Cc: Martin Schwidefsky Signed-off-by: Heiko Carstens Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] lockdep: add graph depth information to /proc/lockdep

2007-02-11T18:51:26+00:00

Generate locking graph information into /proc/lockdep, for lock hierarchy documentation and visualization purposes. sample output: c089fd5c OPS: 138 FD: 14 BD: 1 --..: &tty->termios_mutex -> [c07a3430] tty_ldisc_lock -> [c07a37f0] &port_lock_key -> [c07afdc0] &rq->rq_lock_key#2 The lock classes listed are all the first-hop lock dependencies that lockdep has seen so far. Signed-off-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] lockdep: print irq-trace info on asserts

2006-12-13T17:05:50+00:00

When we print an assert due to scheduling-in-atomic bugs, and if lockdep is enabled, then the IRQ tracing information of lockdep can be printed to pinpoint the code location that disabled interrupts. This saved me quite a bit of debugging time in cases where the backtrace did not identify the irq-disabling site well enough. Signed-off-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds