Commit aa2cc356 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

ratelimit: Force re-initialization when rate-limiting re-enabled 

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: default avatarPaul E. McKenney <paulmck@kernel.org>
Reviewed-by: default avatarPetr 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>
parent 084a990d

lib/ratelimit.c

+14 −1
Original line number Diff line number Diff line
@@ -35,13 +35,26 @@ 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);

		goto unlock_ret;

	}



	/*

	 * If we contend on this state's lock then just check if

	 * the current burst is used or not. It might cause