diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2024-06-10 14:46:39 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2024-06-11 11:25:24 +0200 |
| commit | 9bc2ff871f00437ad2f10c1eceff51aaa72b478f (patch) | |
| tree | cfb7a1396b8d7268761e95c3419293376d972c8b /kernel/jump_label.c | |
| parent | 695ef796467ed228b60f1915995e390aea3d85c6 (diff) | |
jump_label: Simplify and clarify static_key_fast_inc_cpus_locked()
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
Diffstat (limited to 'kernel/jump_label.c')
| -rw-r--r-- | kernel/jump_label.c | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/kernel/jump_label.c b/kernel/jump_label.c index 4d06ec2f3e07..4ad5ed8adf96 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -162,22 +162,24 @@ 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; } |