linux/kernel/locking
Peter Zijlstra a24fc60d63 lockdep: Implement lock pinning
Add a lockdep annotation that WARNs if you 'accidentially' unlock a
lock.

This is especially helpful for code with callbacks, where the upper
layer assumes a lock remains taken but a lower layer thinks it maybe
can drop and reacquire the lock.

By unwittingly breaking up the lock, races can be introduced.

Lock pinning is a lockdep annotation that helps with this, when you
lockdep_pin_lock() a held lock, any unlock without a
lockdep_unpin_lock() will produce a WARN. Think of this as a relative
of lockdep_assert_held(), except you don't only assert its held now,
but ensure it stays held until you release your assertion.

RFC: a possible alternative API would be something like:

  int cookie = lockdep_pin_lock(&foo);
  ...
  lockdep_unpin_lock(&foo, cookie);

Where we pick a random number for the pin_count; this makes it
impossible to sneak a lock break in without also passing the right
cookie along.

I've not done this because it ends up generating code for !LOCKDEP,
esp. if you need to pass the cookie around for some reason.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: ktkhai@parallels.com
Cc: rostedt@goodmis.org
Cc: juri.lelli@gmail.com
Cc: pang.xunlei@linaro.org
Cc: oleg@redhat.com
Cc: wanpeng.li@linux.intel.com
Cc: umgwanakikbuti@gmail.com
Link: http://lkml.kernel.org/r/20150611124743.906731065@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-06-19 00:25:27 +02:00
..
lglock.c locking: Move the lglocks code to kernel/locking/ 2013-11-06 09:24:20 +01:00
lockdep_internals.h lockdep: Increase static allocations 2014-04-18 14:20:50 +02:00
lockdep_proc.c lockdep/proc: Fix lock-time avg computation 2013-11-11 12:41:34 +01:00
lockdep_states.h
lockdep.c lockdep: Implement lock pinning 2015-06-19 00:25:27 +02:00
locktorture.c locktorture: Cleanup header usage 2014-09-30 00:10:02 -07:00
Makefile Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2015-02-11 17:42:32 -08:00
mcs_spinlock.h locking: Remove ACCESS_ONCE() usage 2015-02-24 08:44:16 +01:00
mutex-debug.c mutex: Always clear owner field upon mutex_unlock() 2015-01-09 11:20:39 +01:00
mutex-debug.h
mutex.c locking/mutex: Further simplify mutex_spin_on_owner() 2015-04-09 08:10:23 +02:00
mutex.h locking/mutexes: Use MUTEX_SPIN_ON_OWNER when appropriate 2014-08-13 10:32:02 +02:00
osq_lock.c locking: Remove ACCESS_ONCE() usage 2015-02-24 08:44:16 +01:00
percpu-rwsem.c locking: Move the percpu-rwsem code to kernel/locking/ 2013-11-06 09:24:22 +01:00
qrwlock.c arch, locking: Ciao arch_mutex_cpu_relax() 2014-07-17 12:32:47 +02:00
rtmutex_common.h rtmutex: Cleanup deadlock detector debug logic 2014-06-21 22:05:30 +02:00
rtmutex-debug.c rtmutex: Cleanup deadlock detector debug logic 2014-06-21 22:05:30 +02:00
rtmutex-debug.h rtmutex: Cleanup deadlock detector debug logic 2014-06-21 22:05:30 +02:00
rtmutex-tester.c locking: Move the rtmutex code to kernel/locking/ 2013-11-06 09:23:59 +01:00
rtmutex.c Merge branch 'linus' into timers/core 2015-05-19 16:12:32 +02:00
rtmutex.h rtmutex: Cleanup deadlock detector debug logic 2014-06-21 22:05:30 +02:00
rwsem-spinlock.c locking/rwsem: Document barrier need when waking tasks 2015-02-18 16:57:10 +01:00
rwsem-xadd.c locking/rwsem: Fix lock optimistic spinning when owner is not running 2015-03-07 09:50:49 +01:00
rwsem.c locking/rwsem: Set lock ownership ASAP 2015-02-18 16:57:13 +01:00
rwsem.h locking/rwsem: Set lock ownership ASAP 2015-02-18 16:57:13 +01:00
semaphore.c locking/semaphore: Resolve some shadow warnings 2014-09-04 07:17:24 +02:00
spinlock_debug.c locking: Move the spinlock code to kernel/locking/ 2013-11-06 07:55:21 +01:00
spinlock.c spinlock: Add spin_lock_bh_nested() 2015-01-03 14:32:57 -05:00