forked from luck/tmp_suning_uos_patched
1e820c9608
MUTEX_SHOW_NO_WAITER() is a macro which checks for if there are "no waiters" on a mutex by checking if the lock count is non-negative. Based on feedback from the discussion in the earlier version of this patchset, the macro is not very readable. Furthermore, checking lock->count isn't always the correct way to determine if there are "no waiters" on a mutex. For example, a negative count on a mutex really only means that there "potentially" are waiters. Likewise, there can be waiters on the mutex even if the count is non-negative. Thus, "MUTEX_SHOW_NO_WAITER" doesn't always do what the name of the macro suggests. So this patch deletes the MUTEX_SHOW_NO_WAITERS() macro, directly use atomic_read() instead of the macro, and adds comments which elaborate on how the extra atomic_read() checks can help reduce unnecessary xchg() operations. Signed-off-by: Jason Low <jason.low2@hp.com> Acked-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: akpm@linux-foundation.org Cc: tim.c.chen@linux.intel.com Cc: paulmck@linux.vnet.ibm.com Cc: rostedt@goodmis.org Cc: davidlohr@hp.com Cc: scott.norton@hp.com Cc: aswin@hp.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1402511843-4721-3-git-send-email-jason.low2@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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| .. | ||
| lglock.c | ||
| lockdep_internals.h | ||
| lockdep_proc.c | ||
| lockdep_states.h | ||
| lockdep.c | ||
| locktorture.c | ||
| Makefile | ||
| mcs_spinlock.c | ||
| mcs_spinlock.h | ||
| mutex-debug.c | ||
| mutex-debug.h | ||
| mutex.c | ||
| mutex.h | ||
| percpu-rwsem.c | ||
| qrwlock.c | ||
| rtmutex_common.h | ||
| rtmutex-debug.c | ||
| rtmutex-debug.h | ||
| rtmutex-tester.c | ||
| rtmutex.c | ||
| rtmutex.h | ||
| rwsem-spinlock.c | ||
| rwsem-xadd.c | ||
| rwsem.c | ||
| semaphore.c | ||
| spinlock_debug.c | ||
| spinlock.c | ||