Commit-ID: b92e793bbe4a1c49dbf78d8d526561e7a7dd568a Gitweb: https://git.kernel.org/tip/b92e793bbe4a1c49dbf78d8d526561e7a7dd568a Author: Jakub Kicinski <jakub.kicin...@netronome.com> AuthorDate: Fri, 29 Mar 2019 17:08:53 -0700 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Mon, 29 Apr 2019 08:29:21 +0200
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.kicin...@netronome.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Reviewed-by: Simon Horman <simon.hor...@netronome.com> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Will Deacon <will.dea...@arm.com> Cc: alexei.starovoi...@gmail.com Cc: ard.biesheu...@linaro.org Cc: oss-driv...@netronome.com Cc: yamada.masah...@socionext.com Link: https://lkml.kernel.org/r/20190330000854.30142-3-jakub.kicin...@netronome.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/jump_label.c | 23 +++++++++++++++-------- 1 file 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)) {
