When '.enabled.counter == 1', static_key_slow_dec_deferred() gets
silently dropped if the decrease is already pending.
We print a warning if this happens and because .enabled.counter cannot
go below 1 before the decrease has finished, the number of ignored
static_key_slow_dec_deferred() is kept and we skip an equal amount of
static_key_slow_inc_deferred().
Signed-off-by: Radim Krčmář <rkrcmar@xxxxxxxxxx>
---
include/linux/jump_label_ratelimit.h | 1 +
kernel/jump_label.c | 17 +++++++++++------
2 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/include/linux/jump_label_ratelimit.h b/include/linux/jump_label_ratelimit.h
index a18aded..2d5fa1a 100644
--- a/include/linux/jump_label_ratelimit.h
+++ b/include/linux/jump_label_ratelimit.h
@@ -14,6 +14,7 @@ struct static_key_deferred {
struct static_key key;
unsigned long timeout;
struct delayed_work work;
+ atomic_t enabled_debt;
};
#endif
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 41592ba..bd7ad31 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -77,12 +77,14 @@ EXPORT_SYMBOL_GPL(static_key_slow_inc);
void static_key_slow_inc_deferred(struct static_key_deferred *key)
{
STATIC_KEY_CHECK_USE();
+ if (atomic_dec_if_positive(&key->enabled_debt) >= 0)
+ return;
static_key_slow_inc(&key->key);
}
EXPORT_SYMBOL_GPL(static_key_slow_inc_deferred);
static void __static_key_slow_dec(struct static_key *key,
- unsigned long rate_limit, struct delayed_work *work)
+ struct static_key_deferred *dkey)
{
if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
WARN(atomic_read(&key->enabled) < 0,
@@ -90,9 +92,12 @@ static void __static_key_slow_dec(struct static_key *key,
return;
}
- if (rate_limit) {
+ if (dkey && dkey->timeout) {
atomic_inc(&key->enabled);
- schedule_delayed_work(work, rate_limit);
+ if (!schedule_delayed_work(&dkey->work, dkey->timeout)) {
+ atomic_inc(&dkey->enabled_debt);
+ WARN(1, "jump label: negative deferred count!\n");
+ }
} else {
if (!jump_label_get_branch_default(key))
jump_label_update(key, JUMP_LABEL_DISABLE);
@@ -106,20 +111,20 @@ static 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, NULL);
}
void static_key_slow_dec(struct static_key *key)
{
STATIC_KEY_CHECK_USE();
- __static_key_slow_dec(key, 0, NULL);
+ __static_key_slow_dec(key, NULL);
}
EXPORT_SYMBOL_GPL(static_key_slow_dec);
void static_key_slow_dec_deferred(struct static_key_deferred *key)
{
STATIC_KEY_CHECK_USE();
- __static_key_slow_dec(&key->key, key->timeout, &key->work);
+ __static_key_slow_dec(&key->key, key);
}
EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
--
1.8.4.2
--
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