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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>
hifive-unleashed-5.2
Jakub Kicinski 2019-03-29 17:08:54 -07:00 committed by Ingo Molnar
parent b92e793bbe
commit 94b5f312cf
1 changed files with 13 additions and 19 deletions
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32
kernel/jump_label.c
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@ -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);