cpu-hotplug: replace per-subsystem mutexes with get_online_cpus()
This patch converts the known per-subsystem mutexes to get_online_cpus
put_online_cpus. It also eliminates the CPU_LOCK_ACQUIRE and
CPU_LOCK_RELEASE hotplug notification events.
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/mm/slab.c b/mm/slab.c
index ff31261..40c00da 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -730,8 +730,7 @@
#endif
/*
- * 1. Guard access to the cache-chain.
- * 2. Protect sanity of cpu_online_map against cpu hotplug events
+ * Guard access to the cache-chain.
*/
static DEFINE_MUTEX(cache_chain_mutex);
static struct list_head cache_chain;
@@ -1331,12 +1330,11 @@
int err = 0;
switch (action) {
- case CPU_LOCK_ACQUIRE:
- mutex_lock(&cache_chain_mutex);
- break;
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
+ mutex_lock(&cache_chain_mutex);
err = cpuup_prepare(cpu);
+ mutex_unlock(&cache_chain_mutex);
break;
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
@@ -1373,9 +1371,8 @@
#endif
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
+ mutex_lock(&cache_chain_mutex);
cpuup_canceled(cpu);
- break;
- case CPU_LOCK_RELEASE:
mutex_unlock(&cache_chain_mutex);
break;
}
@@ -2170,6 +2167,7 @@
* We use cache_chain_mutex to ensure a consistent view of
* cpu_online_map as well. Please see cpuup_callback
*/
+ get_online_cpus();
mutex_lock(&cache_chain_mutex);
list_for_each_entry(pc, &cache_chain, next) {
@@ -2396,6 +2394,7 @@
panic("kmem_cache_create(): failed to create slab `%s'\n",
name);
mutex_unlock(&cache_chain_mutex);
+ put_online_cpus();
return cachep;
}
EXPORT_SYMBOL(kmem_cache_create);
@@ -2547,9 +2546,11 @@
int ret;
BUG_ON(!cachep || in_interrupt());
+ get_online_cpus();
mutex_lock(&cache_chain_mutex);
ret = __cache_shrink(cachep);
mutex_unlock(&cache_chain_mutex);
+ put_online_cpus();
return ret;
}
EXPORT_SYMBOL(kmem_cache_shrink);
@@ -2575,6 +2576,7 @@
BUG_ON(!cachep || in_interrupt());
/* Find the cache in the chain of caches. */
+ get_online_cpus();
mutex_lock(&cache_chain_mutex);
/*
* the chain is never empty, cache_cache is never destroyed
@@ -2584,6 +2586,7 @@
slab_error(cachep, "Can't free all objects");
list_add(&cachep->next, &cache_chain);
mutex_unlock(&cache_chain_mutex);
+ put_online_cpus();
return;
}
@@ -2592,6 +2595,7 @@
__kmem_cache_destroy(cachep);
mutex_unlock(&cache_chain_mutex);
+ put_online_cpus();
}
EXPORT_SYMBOL(kmem_cache_destroy);