diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2024-06-10 14:46:37 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2024-06-11 11:25:23 +0200 |
| commit | 695ef796467ed228b60f1915995e390aea3d85c6 (patch) | |
| tree | 6303760e45a615d9712c02520b420d6d10f5b695 /kernel | |
| parent | 83ab38ef0a0b2407d43af9575bb32333fdd74fb2 (diff) | |
jump_label: Clarify condition in static_key_fast_inc_not_disabled()
The second part of
if (v <= 0 || (v + 1) < 0)
is not immediately obvious that it acts as overflow protection.
Check explicitely for v == INT_MAX instead and add a proper comment how
this is used at the call sites.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20240610124406.484973160@linutronix.de
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/jump_label.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/kernel/jump_label.c b/kernel/jump_label.c index 1f05a19918f4..4d06ec2f3e07 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -132,12 +132,15 @@ bool static_key_fast_inc_not_disabled(struct static_key *key) /* * Negative key->enabled has a special meaning: it sends * static_key_slow_inc/dec() down the slow path, and it is non-zero - * so it counts as "enabled" in jump_label_update(). Note that - * atomic_inc_unless_negative() checks >= 0, so roll our own. + * so it counts as "enabled" in jump_label_update(). + * + * The INT_MAX overflow condition is either used by the networking + * code to reset or detected in the slow path of + * static_key_slow_inc_cpuslocked(). */ v = atomic_read(&key->enabled); do { - if (v <= 0 || (v + 1) < 0) + if (v <= 0 || v == INT_MAX) return false; } while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v + 1))); |