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author | Jiri Kosina <jkosina@suse.cz> | 2014-11-20 14:42:02 +0100 |
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committer | Jiri Kosina <jkosina@suse.cz> | 2014-11-20 14:42:02 +0100 |
commit | a02001086bbfb4da35d1228bebc2f1b442db455f (patch) | |
tree | 62ab47936cef06fd08657ca5b6cd1df98c19be57 /kernel/cpu.c | |
parent | eff264efeeb0898408e8c9df72d8a32621035bed (diff) | |
parent | fc14f9c1272f62c3e8d01300f52467c0d9af50f9 (diff) | |
download | linux-a02001086bbfb4da35d1228bebc2f1b442db455f.tar.bz2 |
Merge Linus' tree to be be to apply submitted patches to newer code than
current trivial.git base
Diffstat (limited to 'kernel/cpu.c')
-rw-r--r-- | kernel/cpu.c | 30 |
1 files changed, 28 insertions, 2 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 81e2a388a0f6..90a3d017b90c 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -64,6 +64,8 @@ static struct { * an ongoing cpu hotplug operation. */ int refcount; + /* And allows lockless put_online_cpus(). */ + atomic_t puts_pending; #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map dep_map; @@ -79,6 +81,8 @@ static struct { /* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */ #define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map) +#define cpuhp_lock_acquire_tryread() \ + lock_map_acquire_tryread(&cpu_hotplug.dep_map) #define cpuhp_lock_acquire() lock_map_acquire(&cpu_hotplug.dep_map) #define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map) @@ -91,15 +95,31 @@ void get_online_cpus(void) mutex_lock(&cpu_hotplug.lock); cpu_hotplug.refcount++; mutex_unlock(&cpu_hotplug.lock); - } EXPORT_SYMBOL_GPL(get_online_cpus); +bool try_get_online_cpus(void) +{ + if (cpu_hotplug.active_writer == current) + return true; + if (!mutex_trylock(&cpu_hotplug.lock)) + return false; + cpuhp_lock_acquire_tryread(); + cpu_hotplug.refcount++; + mutex_unlock(&cpu_hotplug.lock); + return true; +} +EXPORT_SYMBOL_GPL(try_get_online_cpus); + void put_online_cpus(void) { if (cpu_hotplug.active_writer == current) return; - mutex_lock(&cpu_hotplug.lock); + if (!mutex_trylock(&cpu_hotplug.lock)) { + atomic_inc(&cpu_hotplug.puts_pending); + cpuhp_lock_release(); + return; + } if (WARN_ON(!cpu_hotplug.refcount)) cpu_hotplug.refcount++; /* try to fix things up */ @@ -141,6 +161,12 @@ void cpu_hotplug_begin(void) cpuhp_lock_acquire(); for (;;) { mutex_lock(&cpu_hotplug.lock); + if (atomic_read(&cpu_hotplug.puts_pending)) { + int delta; + + delta = atomic_xchg(&cpu_hotplug.puts_pending, 0); + cpu_hotplug.refcount -= delta; + } if (likely(!cpu_hotplug.refcount)) break; __set_current_state(TASK_UNINTERRUPTIBLE); |