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Commit d0646a6f authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

jump_label: Add RELEASE barrier after text changes 



In the unlikely case text modification does not fully order things,
add some extra ordering of our own to ensure we only enabled the fast
path after all text is visible.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent be040bea

kernel/jump_label.c

+9 −2
Original line number Diff line number Diff line
@@ -108,7 +108,11 @@ void static_key_slow_inc(struct static_key *key) 
	if (atomic_read(&key->enabled) == 0) {

		atomic_set(&key->enabled, -1);

		jump_label_update(key);

		atomic_set(&key->enabled, 1);

		/*

		 * Ensure that if the above cmpxchg loop observes our positive

		 * value, it must also observe all the text changes.

		 */

		atomic_set_release(&key->enabled, 1);

	} else {

		atomic_inc(&key->enabled);

	}
@@ -130,7 +134,10 @@ void static_key_enable(struct static_key *key) 
	if (atomic_read(&key->enabled) == 0) {

		atomic_set(&key->enabled, -1);

		jump_label_update(key);

		atomic_set(&key->enabled, 1);

		/*

		 * See static_key_slow_inc().

		 */

		atomic_set_release(&key->enabled, 1);

	}

	jump_label_unlock();

	cpus_read_unlock();