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Peter Zijlstra a5e42516a6 locking/mutex: Fix HANDOFF condition 
[ Upstream commit 048661a1f963e9517630f080687d48af79ed784c ]

Yanfei reported that setting HANDOFF should not depend on recomputing
@first, only on @first state. Which would then give:

  if (ww_ctx || !first)
    first = __mutex_waiter_is_first(lock, &waiter);
  if (first)
    __mutex_set_flag(lock, MUTEX_FLAG_HANDOFF);

But because 'ww_ctx || !first' is basically 'always' and the test for
first is relatively cheap, omit that first branch entirely.

Reported-by: Yanfei Xu <yanfei.xu@windriver.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Reviewed-by: Yanfei Xu <yanfei.xu@windriver.com>
Link: https://lore.kernel.org/r/20210630154114.896786297@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
 		2021-09-15 09:47:25 +02:00
..
Makefile locking/rwsem: Merge rwsem.h and rwsem-xadd.c into rwsem.c 2019-06-17 12:27:57 +02:00
lock_events.c locking/lock_events: Don't show pvqspinlock events on bare metal 2019-04-10 10:56:05 +02:00
lock_events.h locking/lock_events: Use raw_cpu_{add,inc}() for stats 2019-06-03 12:32:56 +02:00
lock_events_list.h locking/rwsem: Adaptive disabling of reader optimistic spinning 2019-06-17 12:28:09 +02:00
lockdep.c lockding/lockdep: Avoid to find wrong lock dep path in check_irq_usage() 2021-07-14 16:53:15 +02:00
lockdep_internals.h locking/lockdep: Decrement IRQ context counters when removing lock chain 2020-10-01 13:17:33 +02:00
lockdep_proc.c locking/lockdep: Fix overflow in presentation of average lock-time 2020-09-03 11:26:47 +02:00
lockdep_states.h locking/lockdep: Rework FS_RECLAIM annotation 2017-08-10 12:29:03 +02:00
locktorture.c locktorture: Print ratio of acquisitions, not failures 2020-04-23 10:36:44 +02:00
mcs_spinlock.h locking/mcs: Use smp_cond_load_acquire() in MCS spin loop 2018-04-27 09:48:49 +02:00
mutex-debug.c locking/mutex: clear MUTEX_FLAGS if wait_list is empty due to signal 2021-05-26 12:05:15 +02:00
mutex-debug.h locking/mutex: clear MUTEX_FLAGS if wait_list is empty due to signal 2021-05-26 12:05:15 +02:00
mutex.c locking/mutex: Fix HANDOFF condition 2021-09-15 09:47:25 +02:00
mutex.h locking/mutex: clear MUTEX_FLAGS if wait_list is empty due to signal 2021-05-26 12:05:15 +02:00
osq_lock.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
percpu-rwsem.c Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu 2019-06-28 19:46:47 +02:00
qrwlock.c locking/qrwlock: Fix ordering in queued_write_lock_slowpath() 2021-04-28 13:19:14 +02:00
qspinlock.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157 2019-05-30 11:26:37 -07:00
qspinlock_paravirt.h Revert "locking/pvqspinlock: Don't wait if vCPU is preempted" 2019-09-25 10:22:37 +02:00
qspinlock_stat.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157 2019-05-30 11:26:37 -07:00
rtmutex-debug.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
rtmutex-debug.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
rtmutex.c rtmutex: Remove unused argument from rt_mutex_proxy_unlock() 2021-01-30 13:54:09 +01:00
rtmutex.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
rtmutex_common.h rtmutex: Remove unused argument from rt_mutex_proxy_unlock() 2021-01-30 13:54:09 +01:00
rwsem.c exec: Transform exec_update_mutex into a rw_semaphore 2021-01-09 13:44:55 +01:00
rwsem.h locking/rwsem: Merge rwsem.h and rwsem-xadd.c into rwsem.c 2019-06-17 12:27:57 +02:00
semaphore.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 436 2019-06-05 17:37:17 +02:00
spinlock.c asm-generic/mmiowb: Add generic implementation of mmiowb() tracking 2019-04-08 11:59:39 +01:00
spinlock_debug.c locking/spinlock/debug: Fix various data races 2020-01-12 12:21:13 +01:00
test-ww_mutex.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 9 2019-05-21 11:28:40 +02:00