From: kernel test robot <lkp@intel.com>
To: kbuild@lists.01.org
Subject: kernel/locking/rtmutex.c:1375 rt_mutex_slowunlock() warn: inconsistent returns '&lock->wait_lock'.
Date: Wed, 23 Jun 2021 13:06:00 +0800 [thread overview]
Message-ID: <202106231348.w0XFQoO2-lkp@intel.com> (raw)
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CC: kbuild-all(a)lists.01.org
CC: linux-kernel(a)vger.kernel.org
TO: Thomas Gleixner <tglx@linutronix.de>
CC: Ingo Molnar <mingo@kernel.org>
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 0c18f29aae7ce3dadd26d8ee3505d07cc982df75
commit: 70c80103aafdeae99126694bc1cd54de016bc258 locking/rtmutex: Consolidate the fast/slowpath invocation
date: 3 months ago
:::::: branch date: 11 hours ago
:::::: commit date: 3 months ago
config: powerpc64-randconfig-m031-20210622 (attached as .config)
compiler: powerpc64le-linux-gcc (GCC) 9.3.0
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
smatch warnings:
kernel/locking/rtmutex.c:1375 rt_mutex_slowunlock() warn: inconsistent returns '&lock->wait_lock'.
kernel/locking/rtmutex.c:1375 rt_mutex_slowunlock() warn: inconsistent returns 'flags'.
vim +1375 kernel/locking/rtmutex.c
70c80103aafdea kernel/locking/rtmutex.c Thomas Gleixner 2021-03-26 1311
23f78d4a03c53c kernel/rtmutex.c Ingo Molnar 2006-06-27 1312 /*
802ab58da74bb4 kernel/locking/rtmutex.c Sebastian Andrzej Siewior 2015-06-17 1313 * Slow path to release a rt-mutex.
aa2bfe55366552 kernel/locking/rtmutex.c Peter Zijlstra 2017-03-23 1314 *
aa2bfe55366552 kernel/locking/rtmutex.c Peter Zijlstra 2017-03-23 1315 * Return whether the current task needs to call rt_mutex_postunlock().
23f78d4a03c53c kernel/rtmutex.c Ingo Molnar 2006-06-27 1316 */
70c80103aafdea kernel/locking/rtmutex.c Thomas Gleixner 2021-03-26 1317 static void __sched rt_mutex_slowunlock(struct rt_mutex *lock)
23f78d4a03c53c kernel/rtmutex.c Ingo Molnar 2006-06-27 1318 {
70c80103aafdea kernel/locking/rtmutex.c Thomas Gleixner 2021-03-26 1319 DEFINE_WAKE_Q(wake_q);
b4abf91047cf05 kernel/locking/rtmutex.c Thomas Gleixner 2016-01-13 1320 unsigned long flags;
b4abf91047cf05 kernel/locking/rtmutex.c Thomas Gleixner 2016-01-13 1321
b4abf91047cf05 kernel/locking/rtmutex.c Thomas Gleixner 2016-01-13 1322 /* irqsave required to support early boot calls */
b4abf91047cf05 kernel/locking/rtmutex.c Thomas Gleixner 2016-01-13 1323 raw_spin_lock_irqsave(&lock->wait_lock, flags);
23f78d4a03c53c kernel/rtmutex.c Ingo Molnar 2006-06-27 1324
23f78d4a03c53c kernel/rtmutex.c Ingo Molnar 2006-06-27 1325 debug_rt_mutex_unlock(lock);
23f78d4a03c53c kernel/rtmutex.c Ingo Molnar 2006-06-27 1326
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1327 /*
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1328 * We must be careful here if the fast path is enabled. If we
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1329 * have no waiters queued we cannot set owner to NULL here
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1330 * because of:
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1331 *
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1332 * foo->lock->owner = NULL;
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1333 * rtmutex_lock(foo->lock); <- fast path
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1334 * free = atomic_dec_and_test(foo->refcnt);
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1335 * rtmutex_unlock(foo->lock); <- fast path
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1336 * if (free)
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1337 * kfree(foo);
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1338 * raw_spin_unlock(foo->lock->wait_lock);
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1339 *
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1340 * So for the fastpath enabled kernel:
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1341 *
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1342 * Nothing can set the waiters bit as long as we hold
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1343 * lock->wait_lock. So we do the following sequence:
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1344 *
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1345 * owner = rt_mutex_owner(lock);
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1346 * clear_rt_mutex_waiters(lock);
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1347 * raw_spin_unlock(&lock->wait_lock);
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1348 * if (cmpxchg(&lock->owner, owner, 0) == owner)
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1349 * return;
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1350 * goto retry;
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1351 *
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1352 * The fastpath disabled variant is simple as all access to
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1353 * lock->owner is serialized by lock->wait_lock:
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1354 *
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1355 * lock->owner = NULL;
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1356 * raw_spin_unlock(&lock->wait_lock);
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1357 */
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1358 while (!rt_mutex_has_waiters(lock)) {
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1359 /* Drops lock->wait_lock ! */
b4abf91047cf05 kernel/locking/rtmutex.c Thomas Gleixner 2016-01-13 1360 if (unlock_rt_mutex_safe(lock, flags) == true)
70c80103aafdea kernel/locking/rtmutex.c Thomas Gleixner 2021-03-26 1361 return;
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1362 /* Relock the rtmutex and try again */
b4abf91047cf05 kernel/locking/rtmutex.c Thomas Gleixner 2016-01-13 1363 raw_spin_lock_irqsave(&lock->wait_lock, flags);
23f78d4a03c53c kernel/rtmutex.c Ingo Molnar 2006-06-27 1364 }
23f78d4a03c53c kernel/rtmutex.c Ingo Molnar 2006-06-27 1365
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1366 /*
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1367 * The wakeup next waiter path does not suffer from the above
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1368 * race. See the comments there.
45ab4effc3bee6 kernel/locking/rtmutex.c Davidlohr Bueso 2015-05-19 1369 *
45ab4effc3bee6 kernel/locking/rtmutex.c Davidlohr Bueso 2015-05-19 1370 * Queue the next waiter for wakeup once we release the wait_lock.
27e35715df54cb kernel/locking/rtmutex.c Thomas Gleixner 2014-06-11 1371 */
70c80103aafdea kernel/locking/rtmutex.c Thomas Gleixner 2021-03-26 1372 mark_wakeup_next_waiter(&wake_q, lock);
b4abf91047cf05 kernel/locking/rtmutex.c Thomas Gleixner 2016-01-13 1373 raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
23f78d4a03c53c kernel/rtmutex.c Ingo Molnar 2006-06-27 1374
70c80103aafdea kernel/locking/rtmutex.c Thomas Gleixner 2021-03-26 @1375 rt_mutex_postunlock(&wake_q);
23f78d4a03c53c kernel/rtmutex.c Ingo Molnar 2006-06-27 1376 }
23f78d4a03c53c kernel/rtmutex.c Ingo Molnar 2006-06-27 1377
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org
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next reply other threads:[~2021-06-23 5:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-23 5:06 kernel test robot [this message]
-- strict thread matches above, loose matches on Subject: below --
2021-11-19 11:22 kernel/locking/rtmutex.c:1375 rt_mutex_slowunlock() warn: inconsistent returns '&lock->wait_lock' kernel test robot
2021-11-26 5:22 kernel test robot
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