linux-toradex.git/kernel/locking/mutex.c, branch v5.14-rc6

sched: Change task_struct::state

2021-06-18T09:43:09+00:00

Change the type and name of task_struct::state. Drop the volatile and
shrink it to an 'unsigned int'. Rename it in order to find all uses
such that we can use READ_ONCE/WRITE_ONCE as appropriate.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Daniel Bristot de Oliveira 
Acked-by: Will Deacon 
Acked-by: Daniel Thompson 
Link: https://lore.kernel.org/r/20210611082838.550736351@infradead.org

locking/mutex: clear MUTEX_FLAGS if wait_list is empty due to signal

2021-05-18T10:53:51+00:00

When a interruptible mutex locker is interrupted by a signal
without acquiring this lock and removed from the wait queue.
if the mutex isn't contended enough to have a waiter
put into the wait queue again, the setting of the WAITER
bit will force mutex locker to go into the slowpath to
acquire the lock every time, so if the wait queue is empty,
the WAITER bit need to be clear.

Fixes: 040a0a371005 ("mutex: Add support for wound/wait style locks")
Suggested-by: Peter Zijlstra 
Signed-off-by: Zqiang 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20210517034005.30828-1-qiang.zhang@windriver.com

locking: Fix typos in comments

2021-03-22T01:45:52+00:00

Fix ~16 single-word typos in locking code comments.

Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Paul E. McKenney 
Cc: Will Deacon 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

locking/ww_mutex: Simplify use_ww_ctx & ww_ctx handling

2021-03-17T08:56:44+00:00

The use_ww_ctx flag is passed to mutex_optimistic_spin(), but the
function doesn't use it. The frequent use of the (use_ww_ctx && ww_ctx)
combination is repetitive.

In fact, ww_ctx should not be used at all if !use_ww_ctx.  Simplify
ww_mutex code by dropping use_ww_ctx from mutex_optimistic_spin() an
clear ww_ctx if !use_ww_ctx. In this way, we can replace (use_ww_ctx &&
ww_ctx) by just (ww_ctx).

Signed-off-by: Waiman Long 
Signed-off-by: Ingo Molnar 
Acked-by: Davidlohr Bueso 
Link: https://lore.kernel.org/r/20210316153119.13802-2-longman@redhat.com

locking/mutex: Kill mutex_trylock_recursive()

2021-02-10T13:44:40+00:00

There are not users of mutex_trylock_recursive() in tree as of
v5.11-rc7.

Remove it.

Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20210210085248.219210-2-bigeasy@linutronix.de

Revert "locking/mutex: Complain upon mutex API misuse in IRQ contexts"

2019-12-10T23:27:43+00:00

This ended up causing some noise in places such as rxrpc running in softirq.

The warning is misleading in this case as the mutex trylock and unlock
operations are done within the same context; and therefore we need not
worry about the PI-boosting issues that comes along with no single-owner
lock guarantees.

While we don't want to support this in mutexes, there is no way out of
this yet; so lets get rid of the WARNs for now, as it is only fair to
code that has historically relied on non-preemptible softirq guarantees.
In addition, changing the lock type is also unviable: exclusive rwsems
have the same issue (just not the WARN_ON) and counting semaphores
would introduce a performance hit as mutexes are a lot more optimized.

This reverts:

    a0855d24fc22: ("locking/mutex: Complain upon mutex API misuse in IRQ contexts")

Fixes: a0855d24fc22: ("locking/mutex: Complain upon mutex API misuse in IRQ contexts")
Signed-off-by: Davidlohr Bueso 
Tested-by: David Howells 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-afs@lists.infradead.org
Cc: linux-fsdevel@vger.kernel.org
Cc: will@kernel.org
Link: https://lkml.kernel.org/r/20191210220523.28540-1-dave@stgolabs.net
Signed-off-by: Ingo Molnar

locking/mutex: Complain upon mutex API misuse in IRQ contexts

2019-10-29T11:22:52+00:00

Add warning checks if mutex_trylock() or mutex_unlock() are used in
IRQ contexts, under CONFIG_DEBUG_MUTEXES=y.

While the mutex rules and semantics are explicitly documented, this allows
to expose any abusers and robustifies the whole thing.

While trylock and unlock are non-blocking, calling from IRQ context
is still forbidden (lock must be within the same context as unlock).

Signed-off-by: Davidlohr Bueso 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: dave@stgolabs.net
Link: https://lkml.kernel.org/r/20191025033634.3330-1-dave@stgolabs.net
Signed-off-by: Ingo Molnar

locking/lockdep: Remove unused @nested argument from lock_release()

2019-10-09T10:46:10+00:00

Since the following commit:

  b4adfe8e05f1 ("locking/lockdep: Remove unused argument in __lock_release")

@nested is no longer used in lock_release(), so remove it from all
lock_release() calls and friends.

Signed-off-by: Qian Cai 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Will Deacon 
Acked-by: Daniel Vetter 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: airlied@linux.ie
Cc: akpm@linux-foundation.org
Cc: alexander.levin@microsoft.com
Cc: daniel@iogearbox.net
Cc: davem@davemloft.net
Cc: dri-devel@lists.freedesktop.org
Cc: duyuyang@gmail.com
Cc: gregkh@linuxfoundation.org
Cc: hannes@cmpxchg.org
Cc: intel-gfx@lists.freedesktop.org
Cc: jack@suse.com
Cc: jlbec@evilplan.or
Cc: joonas.lahtinen@linux.intel.com
Cc: joseph.qi@linux.alibaba.com
Cc: jslaby@suse.com
Cc: juri.lelli@redhat.com
Cc: maarten.lankhorst@linux.intel.com
Cc: mark@fasheh.com
Cc: mhocko@kernel.org
Cc: mripard@kernel.org
Cc: ocfs2-devel@oss.oracle.com
Cc: rodrigo.vivi@intel.com
Cc: sean@poorly.run
Cc: st@kernel.org
Cc: tj@kernel.org
Cc: tytso@mit.edu
Cc: vdavydov.dev@gmail.com
Cc: vincent.guittot@linaro.org
Cc: viro@zeniv.linux.org.uk
Link: https://lkml.kernel.org/r/1568909380-32199-1-git-send-email-cai@lca.pw
Signed-off-by: Ingo Molnar

mutex: Fix up mutex_waiter usage

2019-08-08T07:09:25+00:00

The patch moving bits into mutex.c was a little too much; by also
moving struct mutex_waiter a few less common CONFIGs would no longer
build.

Fixes: 5f35d5a66b3e ("locking/mutex: Make __mutex_owner static to mutex.c")
Signed-off-by: Peter Zijlstra (Intel)

locking/mutex: Use mutex flags macro instead of hard code

2019-08-06T10:49:16+00:00

Use the mutex flag macro instead of hard code value inside
__mutex_owner().

Signed-off-by: Mukesh Ojha 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: mingo@redhat.com
Cc: will@kernel.org
Link: https://lkml.kernel.org/r/1564585504-3543-2-git-send-email-mojha@codeaurora.org