From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Subject: [PATCH v2 4/5] static_key: keep deferred enabled counter debt Date: Sat, 7 Dec 2013 01:40:05 +0100 Message-ID: <1386376806-924-5-git-send-email-rkrcmar@redhat.com> References: <1386376806-924-1-git-send-email-rkrcmar@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1386376806-924-1-git-send-email-rkrcmar@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, linux-arch@vger.kernel.org, rostedt@goodmis.org, pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, arnd@arndb.de, rusty@rustcorp.com.au, =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= List-Id: linux-arch.vger.kernel.org When '.enabled.counter =3D=3D 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 Kr=C4=8Dm=C3=A1=C5=99 --- 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 =20 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) >=3D 0) + return; static_key_slow_inc(&key->key); } EXPORT_SYMBOL_GPL(static_key_slow_inc_deferred); =20 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; } =20 - 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 =3D container_of(work, struct static_key_deferred, work.work); - __static_key_slow_dec(&key->key, 0, NULL); + __static_key_slow_dec(&key->key, NULL); } =20 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); =20 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); =20 --=20 1.8.4.2 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:53502 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758884Ab3LGAl0 (ORCPT ); Fri, 6 Dec 2013 19:41:26 -0500 From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Subject: [PATCH v2 4/5] static_key: keep deferred enabled counter debt Date: Sat, 7 Dec 2013 01:40:05 +0100 Message-ID: <1386376806-924-5-git-send-email-rkrcmar@redhat.com> In-Reply-To: <1386376806-924-1-git-send-email-rkrcmar@redhat.com> References: <1386376806-924-1-git-send-email-rkrcmar@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, linux-arch@vger.kernel.org, rostedt@goodmis.org, pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, arnd@arndb.de, rusty@rustcorp.com.au, =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Message-ID: <20131207004005.RpCSiegShY_J5n4YSbTadXqGWNVhbBMxlZONBo-vN5Q@z> 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 --- 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