]> git.ipfire.org Git - thirdparty/kernel/linux.git/commitdiff
ratelimit: Force re-initialization when rate-limiting re-enabled
authorPaul E. McKenney <paulmck@kernel.org>
Wed, 23 Apr 2025 19:03:59 +0000 (12:03 -0700)
committerPaul E. McKenney <paulmck@kernel.org>
Thu, 8 May 2025 23:13:27 +0000 (16:13 -0700)
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>
Reviewed-by: 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

index 7a7ba4835639fd37540d82d83687b84e9cac7c2a..7d4f4e241213e55c2fa123fdb24a849b1664e718 100644 (file)
@@ -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;
        }
 
        /*