diff options
author | Jakub Kicinski <jakub.kicinski@netronome.com> | 2019-03-30 03:08:54 +0300 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2019-04-29 09:29:21 +0300 |
commit | 94b5f312cfb4a66055d9b688dc9ab6b297eb9dcc (patch) | |
tree | 7a4dc14eb16fa750262bb6cc3252d0e106fea8d4 /kernel/jump_label.c | |
parent | b92e793bbe4a1c49dbf78d8d526561e7a7dd568a (diff) |
locking/static_key: Don't take sleeping locks in __static_key_slow_dec_deferred()
Changing jump_label state is protected by jump_label_lock().
Rate limited static_key_slow_dec(), however, will never
directly call jump_label_update(), it will schedule a delayed
work instead. Therefore it's unnecessary to take both the
cpus_read_lock() and jump_label_lock().
This allows static_key_slow_dec_deferred() to be called
from atomic contexts, like socket destructing in net/tls,
without the need for another indirection.
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/20190330000854.30142-4-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.c | 32 |
1 files changed, 13 insertions, 19 deletions
diff --git a/kernel/jump_label.c b/kernel/jump_label.c index 02c3d11264dd..de6efdecc70d 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -221,9 +221,7 @@ static bool static_key_slow_try_dec(struct static_key *key) return true; } -static void __static_key_slow_dec_cpuslocked(struct static_key *key, - unsigned long rate_limit, - struct delayed_work *work) +static void __static_key_slow_dec_cpuslocked(struct static_key *key) { lockdep_assert_cpus_held(); @@ -231,23 +229,15 @@ static void __static_key_slow_dec_cpuslocked(struct static_key *key, return; jump_label_lock(); - if (atomic_dec_and_test(&key->enabled)) { - if (rate_limit) { - atomic_inc(&key->enabled); - schedule_delayed_work(work, rate_limit); - } else { - jump_label_update(key); - } - } + if (atomic_dec_and_test(&key->enabled)) + jump_label_update(key); jump_label_unlock(); } -static void __static_key_slow_dec(struct static_key *key, - unsigned long rate_limit, - struct delayed_work *work) +static void __static_key_slow_dec(struct static_key *key) { cpus_read_lock(); - __static_key_slow_dec_cpuslocked(key, rate_limit, work); + __static_key_slow_dec_cpuslocked(key); cpus_read_unlock(); } @@ -255,21 +245,21 @@ void jump_label_update_timeout(struct work_struct *work) { struct static_key_deferred *key = container_of(work, struct static_key_deferred, work.work); - __static_key_slow_dec(&key->key, 0, NULL); + __static_key_slow_dec(&key->key); } EXPORT_SYMBOL_GPL(jump_label_update_timeout); void static_key_slow_dec(struct static_key *key) { STATIC_KEY_CHECK_USE(key); - __static_key_slow_dec(key, 0, NULL); + __static_key_slow_dec(key); } EXPORT_SYMBOL_GPL(static_key_slow_dec); void static_key_slow_dec_cpuslocked(struct static_key *key) { STATIC_KEY_CHECK_USE(key); - __static_key_slow_dec_cpuslocked(key, 0, NULL); + __static_key_slow_dec_cpuslocked(key); } void __static_key_slow_dec_deferred(struct static_key *key, @@ -277,7 +267,11 @@ void __static_key_slow_dec_deferred(struct static_key *key, unsigned long timeout) { STATIC_KEY_CHECK_USE(key); - __static_key_slow_dec(key, timeout, work); + + if (static_key_slow_try_dec(key)) + return; + + schedule_delayed_work(work, timeout); } EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred); |