Currently, if rate limiting is disabled, ___ratelimit() does an immediate
early return with no state changes. This can result in false-positive
drops when re-enabling rate limiting. Therefore, mark the ratelimit_state
structure "uninitialized" when rate limiting is disabled.
[ paulmck: Apply Petr Mladek feedback. ]
Link: https://lore.kernel.org/all/fbe93a52-365e-47fe-93a4-44a44547d601@paulmck-laptop/
Link: https://lore.kernel.org/all/20250423115409.3425-1-spasswolf@web.de/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
---
lib/ratelimit.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/lib/ratelimit.c b/lib/ratelimit.c
index 7a7ba4835639f..7d4f4e241213e 100644
--- a/lib/ratelimit.c
+++ b/lib/ratelimit.c
@@ -35,11 +35,24 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
unsigned long flags;
int ret;
+ /*
+ * Zero interval says never limit, otherwise, non-positive burst
+ * says always limit.
+ */
if (interval <= 0 || burst <= 0) {
ret = interval == 0 || burst > 0;
+ if (!(READ_ONCE(rs->flags) & RATELIMIT_INITIALIZED) || (!interval && !burst) ||
+ !raw_spin_trylock_irqsave(&rs->lock, flags)) {
+ if (!ret)
+ ratelimit_state_inc_miss(rs);
+ return ret;
+ }
+
+ /* Force re-initialization once re-enabled. */
+ rs->flags &= ~RATELIMIT_INITIALIZED;
if (!ret)
ratelimit_state_inc_miss(rs);
- return ret;
+ goto unlock_ret;
}
/*
--
2.40.1