locking/static_key: Factor out the fast path of static_key_slow_dec() (b92e793b) · Commits · 戴 / test

static_key_slow_dec() checks if the atomic enable count is larger than 1, and if so there decrements it before taking the jump_label_lock. Move this logic into a helper for reuse in rate limitted keys. Signed-off-by:

Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by:

Simon Horman <simon.horman@netronome.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: alexei.starovoitov@gmail.com Cc: ard.biesheuvel@linaro.org Cc: oss-drivers@netronome.com Cc: yamada.masahiro@socionext.com Link: https://lkml.kernel.org/r/20190330000854.30142-3-jakub.kicinski@netronome.com Signed-off-by:

Ingo Molnar <mingo@kernel.org>

kernel/jump_label.c

+15 −8

Original line number	Diff line number	Diff line
		@@ -202,13 +202,13 @@ void static_key_disable(struct static_key *key)
		}
		EXPORT_SYMBOL_GPL(static_key_disable);

		static void __static_key_slow_dec_cpuslocked(struct static_key *key,
		unsigned long rate_limit,
		struct delayed_work *work)
		static bool static_key_slow_try_dec(struct static_key *key)
		{
		int val;

		lockdep_assert_cpus_held();
		val = atomic_fetch_add_unless(&key->enabled, -1, 1);
		if (val == 1)
		return false;

		/*
		* The negative count check is valid even when a negative
		@@ -217,12 +217,19 @@ static void __static_key_slow_dec_cpuslocked(struct static_key *key,
		* returns is unbalanced, because all other static_key_slow_inc()
		* instances block while the update is in progress.
		*/
		val = atomic_fetch_add_unless(&key->enabled, -1, 1);
		if (val != 1) {
		WARN(val < 0, "jump label: negative count!\n");
		return;
		return true;
		}

		static void __static_key_slow_dec_cpuslocked(struct static_key *key,
		unsigned long rate_limit,
		struct delayed_work *work)
		{
		lockdep_assert_cpus_held();

		if (static_key_slow_try_dec(key))
		return;

		jump_label_lock();
		if (atomic_dec_and_test(&key->enabled)) {
		if (rate_limit) {

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