Merge tag 'ratelimit.2025.05.25a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull rate-limit updates from Paul McKenney:
 "lib/ratelimit: Reduce false-positive and silent misses:

   - Reduce open-coded use of ratelimit_state structure fields.

   - Convert the ->missed field to atomic_t.

   - Count misses that are due to lock contention.

   - Eliminate jiffies=0 special case.

   - Reduce ___ratelimit() false-positive rate limiting (Petr Mladek).

   - Allow zero ->burst to hard-disable rate limiting.

   - Optimize away atomic operations when a miss is guaranteed.

   - Warn if ->interval or ->burst are negative (Petr Mladek).

   - Simplify the resulting code.

  A smoke test and stress test have been created, but they are not yet
  ready for mainline. With luck, we will offer them for the v6.17 merge
  window"

* tag 'ratelimit.2025.05.25a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  ratelimit: Drop redundant accesses to burst
  ratelimit: Use nolock_ret restructuring to collapse common case code
  ratelimit: Use nolock_ret label to collapse lock-failure code
  ratelimit: Use nolock_ret label to save a couple of lines of code
  ratelimit: Simplify common-case exit path
  ratelimit: Warn if ->interval or ->burst are negative
  ratelimit: Avoid atomic decrement under lock if already rate-limited
  ratelimit: Avoid atomic decrement if already rate-limited
  ratelimit: Don't flush misses counter if RATELIMIT_MSG_ON_RELEASE
  ratelimit: Force re-initialization when rate-limiting re-enabled
  ratelimit: Allow zero ->burst to disable ratelimiting
  ratelimit: Reduce ___ratelimit() false-positive rate limiting
  ratelimit: Avoid jiffies=0 special case
  ratelimit: Count misses due to lock contention
  ratelimit: Convert the ->missed field to atomic_t
  drm/amd/pm: Avoid open-coded use of ratelimit_state structure's internals
  drm/i915: Avoid open-coded use of ratelimit_state structure's ->missed field
  random: Avoid open-coded use of ratelimit_state structure's ->missed field
  ratelimit: Create functions to handle ratelimit_state internals

1 files changed, 5 insertions, 4 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 1ddc3e2ce62f..b8b24b6ed3fe 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -727,6 +727,7 @@ static void __cold _credit_init_bits(size_t bits)
 	static DECLARE_WORK(set_ready, crng_set_ready);
 	unsigned int new, orig, add;
 	unsigned long flags;
+	int m;
 
 	if (!bits)
 		return;
@@ -749,9 +750,9 @@ static void __cold _credit_init_bits(size_t bits)
 		wake_up_interruptible(&crng_init_wait);
 		kill_fasync(&fasync, SIGIO, POLL_IN);
 		pr_notice("crng init done\n");
-		if (urandom_warning.missed)
-			pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
-				  urandom_warning.missed);
+		m = ratelimit_state_get_miss(&urandom_warning);
+		if (m)
+			pr_notice("%d urandom warning(s) missed due to ratelimiting\n", m);
 	} else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) {
 		spin_lock_irqsave(&base_crng.lock, flags);
 		/* Check if crng_init is CRNG_EMPTY, to avoid race with crng_reseed(). */
@@ -1467,7 +1468,7 @@ static ssize_t urandom_read_iter(struct kiocb *kiocb, struct iov_iter *iter)
 
 	if (!crng_ready()) {
 		if (!ratelimit_disable && maxwarn <= 0)
-			++urandom_warning.missed;
+			ratelimit_state_inc_miss(&urandom_warning);
 		else if (ratelimit_disable || __ratelimit(&urandom_warning)) {
 			--maxwarn;
 			pr_notice("%s: uninitialized urandom read (%zu bytes read)\n",