ratelimit: Convert the ->missed field to atomic_t

The ratelimit_state structure's ->missed field is sometimes incremented
locklessly, and it would be good to avoid lost counts.  This is also
needed to count the number of misses due to trylock failure.  Therefore,
convert the ratelimit_state structure's ->missed field to atomic_t.

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>

diff --git a/include/linux/ratelimit.h b/include/linux/ratelimit.h
index 8400c5356c187b089cf84c5f4c6c04cc98476d4d..c78b92b3e5cd833a5c8570a7657e26a0bd74c384 100644 (file)
--- a/include/linux/ratelimit.h
+++ b/include/linux/ratelimit.h
@@ -24,20 +24,17 @@ static inline void ratelimit_default_init(struct ratelimit_state *rs)
 
 static inline void ratelimit_state_inc_miss(struct ratelimit_state *rs)
 {
-       rs->missed++;
+       atomic_inc(&rs->missed);
 }
 
 static inline int ratelimit_state_get_miss(struct ratelimit_state *rs)
 {
-       return rs->missed;
+       return atomic_read(&rs->missed);
 }
 
 static inline int ratelimit_state_reset_miss(struct ratelimit_state *rs)
 {
-       int ret = rs->missed;
-
-       rs->missed = 0;
-       return ret;
+       return atomic_xchg_relaxed(&rs->missed, 0);
 }
 
 static inline void ratelimit_state_reset_interval(struct ratelimit_state *rs, int interval_init)

diff --git a/include/linux/ratelimit_types.h b/include/linux/ratelimit_types.h
index 765232ce0b5e9986bbf686155c1237edd6bb0a96..d21fe82b67f67e67b3386124ca503ae0025a6796 100644 (file)
--- a/include/linux/ratelimit_types.h
+++ b/include/linux/ratelimit_types.h
@@ -18,7 +18,7 @@ struct ratelimit_state {
        int             interval;
        int             burst;
        int             printed;
-       int             missed;
+       atomic_t        missed;
        unsigned int    flags;
        unsigned long   begin;
 };

diff --git a/lib/ratelimit.c b/lib/ratelimit.c
index 85e22f00180c5bdd180647514e289fb51ef21034..18703f92d73e746baa867dc24e03200529ef5934 100644 (file)
--- a/lib/ratelimit.c
+++ b/lib/ratelimit.c
@@ -66,7 +66,7 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
                rs->printed++;
                ret = 1;
        } else {
-               rs->missed++;
+               ratelimit_state_inc_miss(rs);
                ret = 0;
        }
        raw_spin_unlock_irqrestore(&rs->lock, flags);