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authorJakub Kicinski <jakub.kicinski@netronome.com>2019-03-29 17:08:53 -0700
committerIngo Molnar <mingo@kernel.org>2019-04-29 08:29:21 +0200
commitb92e793bbe4a1c49dbf78d8d526561e7a7dd568a (patch)
tree981f93f26cadc142d2b2280f1d9d8f60a9890e1c /kernel/jump_label.c
parentad282a8117d5048398f506f20b092c14b3b3c43f (diff)
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locking/static_key: Factor out the fast path of static_key_slow_dec()
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>
Diffstat (limited to 'kernel/jump_label.c')
-rw-r--r--kernel/jump_label.c23
1 files changed, 15 insertions, 8 deletions
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 73bbbaddbd9c..02c3d11264dd 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -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
@@ -217,11 +217,18 @@ 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");
+ WARN(val < 0, "jump label: negative count!\n");
+ 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)) {