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>
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@ -221,9 +221,7 @@ static bool static_key_slow_try_dec(struct static_key *key)
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return true;
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}
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static void __static_key_slow_dec_cpuslocked(struct static_key *key,
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unsigned long rate_limit,
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struct delayed_work *work)
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static void __static_key_slow_dec_cpuslocked(struct static_key *key)
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{
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lockdep_assert_cpus_held();
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@ -231,23 +229,15 @@ static void __static_key_slow_dec_cpuslocked(struct static_key *key,
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return;
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jump_label_lock();
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if (atomic_dec_and_test(&key->enabled)) {
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if (rate_limit) {
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atomic_inc(&key->enabled);
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schedule_delayed_work(work, rate_limit);
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} else {
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jump_label_update(key);
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}
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}
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if (atomic_dec_and_test(&key->enabled))
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jump_label_update(key);
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jump_label_unlock();
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}
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static void __static_key_slow_dec(struct static_key *key,
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unsigned long rate_limit,
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struct delayed_work *work)
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static void __static_key_slow_dec(struct static_key *key)
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{
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cpus_read_lock();
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__static_key_slow_dec_cpuslocked(key, rate_limit, work);
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__static_key_slow_dec_cpuslocked(key);
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cpus_read_unlock();
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}
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@ -255,21 +245,21 @@ void jump_label_update_timeout(struct work_struct *work)
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{
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struct static_key_deferred *key =
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container_of(work, struct static_key_deferred, work.work);
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__static_key_slow_dec(&key->key, 0, NULL);
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__static_key_slow_dec(&key->key);
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}
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EXPORT_SYMBOL_GPL(jump_label_update_timeout);
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void static_key_slow_dec(struct static_key *key)
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{
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STATIC_KEY_CHECK_USE(key);
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__static_key_slow_dec(key, 0, NULL);
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__static_key_slow_dec(key);
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}
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EXPORT_SYMBOL_GPL(static_key_slow_dec);
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void static_key_slow_dec_cpuslocked(struct static_key *key)
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{
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STATIC_KEY_CHECK_USE(key);
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__static_key_slow_dec_cpuslocked(key, 0, NULL);
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__static_key_slow_dec_cpuslocked(key);
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}
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void __static_key_slow_dec_deferred(struct static_key *key,
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@ -277,7 +267,11 @@ void __static_key_slow_dec_deferred(struct static_key *key,
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unsigned long timeout)
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{
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STATIC_KEY_CHECK_USE(key);
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__static_key_slow_dec(key, timeout, work);
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if (static_key_slow_try_dec(key))
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return;
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schedule_delayed_work(work, timeout);
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}
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EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred);
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