Kernel/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2025-01-06 13:16:22 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

jump_label: Simplify and clarify static_key_fast_inc_cpus_locked()

Browse Source 
[ Upstream commit 9bc2ff871f ]

Make the code more obvious and add proper comments to avoid future head
scratching.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20240610124406.548322963@linutronix.de
Stable-dep-of: 1d7f856c2c ("jump_label: Fix static_key_slow_dec() yet again")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Thomas Gleixner 2024-06-10 14:46:39 +02:00 committed by Greg Kroah-Hartman
parent ea2cdf4da0
commit 0f05d6c337
1 changed files with 11 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
kernel/jump_label.c
View File

@ -159,22 +159,24 @@ bool static_key_slow_inc_cpuslocked(struct static_key *key)
if (static_key_fast_inc_not_disabled(key))
return true;
jump_label_lock();
if (atomic_read(&key->enabled) == 0) {
atomic_set(&key->enabled, -1);
guard(mutex)(&jump_label_mutex);
/* Try to mark it as 'enabling in progress. */
if (!atomic_cmpxchg(&key->enabled, 0, -1)) {
jump_label_update(key);
/*
* Ensure that if the above cmpxchg loop observes our positive
* value, it must also observe all the text changes.
* Ensure that when static_key_fast_inc_not_disabled() or
* static_key_slow_try_dec() observe the positive value,
* they must also observe all the text changes.
*/
atomic_set_release(&key->enabled, 1);
} else {
if (WARN_ON_ONCE(!static_key_fast_inc_not_disabled(key))) {
jump_label_unlock();
/*
* While holding the mutex this should never observe
* anything else than a value >= 1 and succeed
*/
if (WARN_ON_ONCE(!static_key_fast_inc_not_disabled(key)))
return false;
}
}
jump_label_unlock();
return true;
}