From: marc.zyngier@arm.com (Marc Zyngier)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 2/4] jump_label: Split out code under the hotplug lock
Date: Tue, 1 Aug 2017 09:02:55 +0100 [thread overview]
Message-ID: <20170801080257.5056-3-marc.zyngier@arm.com> (raw)
In-Reply-To: <20170801080257.5056-1-marc.zyngier@arm.com>
In order to later introduce an "already locked" version of some
of the static key funcions, let's split the code into the core stuff
(the *_cpuslocked functions) and the usual helpers, which now
take/release the hotplug lock and call into the _cpuslocked
versions.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
kernel/jump_label.c | 28 +++++++++++++++++++---------
1 file changed, 19 insertions(+), 9 deletions(-)
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index f11b10091100..0ab8b35daa54 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -101,11 +101,10 @@ void static_key_disable(struct static_key *key)
}
EXPORT_SYMBOL_GPL(static_key_disable);
-void static_key_slow_inc(struct static_key *key)
+static void static_key_slow_inc_cpuslocked(struct static_key *key)
{
int v, v1;
- cpus_read_lock();
STATIC_KEY_CHECK_USE();
/*
@@ -122,10 +121,8 @@ void static_key_slow_inc(struct static_key *key)
*/
for (v = atomic_read(&key->enabled); v > 0; v = v1) {
v1 = atomic_cmpxchg(&key->enabled, v, v + 1);
- if (likely(v1 == v)) {
- cpus_read_unlock();
+ if (likely(v1 == v))
return;
- }
}
jump_label_lock();
@@ -137,14 +134,20 @@ void static_key_slow_inc(struct static_key *key)
atomic_inc(&key->enabled);
}
jump_label_unlock();
+}
+
+void static_key_slow_inc(struct static_key *key)
+{
+ cpus_read_lock();
+ static_key_slow_inc_cpuslocked(key);
cpus_read_unlock();
}
EXPORT_SYMBOL_GPL(static_key_slow_inc);
-static void __static_key_slow_dec(struct static_key *key,
- unsigned long rate_limit, struct delayed_work *work)
+static void static_key_slow_dec_cpuslocked(struct static_key *key,
+ unsigned long rate_limit,
+ struct delayed_work *work)
{
- cpus_read_lock();
/*
* The negative count check is valid even when a negative
* key->enabled is in use by static_key_slow_inc(); a
@@ -155,7 +158,6 @@ static void __static_key_slow_dec(struct static_key *key,
if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
WARN(atomic_read(&key->enabled) < 0,
"jump label: negative count!\n");
- cpus_read_unlock();
return;
}
@@ -166,6 +168,14 @@ static void __static_key_slow_dec(struct static_key *key,
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)
+{
+ cpus_read_lock();
+ static_key_slow_dec_cpuslocked(key, rate_limit, work);
cpus_read_unlock();
}
--
2.11.0
next prev parent reply other threads:[~2017-08-01 8:02 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-01 8:02 [PATCH v2 0/4] Working around CPU hotplug and static keys locking Marc Zyngier
2017-08-01 8:02 ` [PATCH v2 1/4] jump_label: Move cpu hotplug locking Marc Zyngier
2017-08-01 8:02 ` Marc Zyngier [this message]
2017-08-01 8:02 ` [PATCH v2 3/4] jump_label: Provide hotplug context variants Marc Zyngier
2017-08-02 14:37 ` Peter Zijlstra
2017-08-02 15:02 ` Marc Zyngier
2017-08-01 8:02 ` [PATCH v2 4/4] clocksource/arm_arch_timer: Use static_branch_enable_cpuslocked() Marc Zyngier
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