Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
authorLinus Torvalds <torvalds@linux-foundation.org>
Sat, 24 Dec 2011 05:47:28 +0000 (21:47 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 24 Dec 2011 05:47:28 +0000 (21:47 -0800)
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  VFS: Fix race between CPU hotplug and lglocks

include/linux/lglock.h

index f549056..87f402c 100644 (file)
@@ -22,6 +22,7 @@
 #include <linux/spinlock.h>
 #include <linux/lockdep.h>
 #include <linux/percpu.h>
+#include <linux/cpu.h>
 
 /* can make br locks by using local lock for read side, global lock for write */
 #define br_lock_init(name)     name##_lock_init()
 
 #define DEFINE_LGLOCK(name)                                            \
                                                                        \
+ DEFINE_SPINLOCK(name##_cpu_lock);                                     \
+ cpumask_t name##_cpus __read_mostly;                                  \
  DEFINE_PER_CPU(arch_spinlock_t, name##_lock);                         \
  DEFINE_LGLOCK_LOCKDEP(name);                                          \
                                                                        \
+ static int                                                            \
+ name##_lg_cpu_callback(struct notifier_block *nb,                     \
+                               unsigned long action, void *hcpu)       \
+ {                                                                     \
+       switch (action & ~CPU_TASKS_FROZEN) {                           \
+       case CPU_UP_PREPARE:                                            \
+               spin_lock(&name##_cpu_lock);                            \
+               cpu_set((unsigned long)hcpu, name##_cpus);              \
+               spin_unlock(&name##_cpu_lock);                          \
+               break;                                                  \
+       case CPU_UP_CANCELED: case CPU_DEAD:                            \
+               spin_lock(&name##_cpu_lock);                            \
+               cpu_clear((unsigned long)hcpu, name##_cpus);            \
+               spin_unlock(&name##_cpu_lock);                          \
+       }                                                               \
+       return NOTIFY_OK;                                               \
+ }                                                                     \
+ static struct notifier_block name##_lg_cpu_notifier = {               \
+       .notifier_call = name##_lg_cpu_callback,                        \
+ };                                                                    \
  void name##_lock_init(void) {                                         \
        int i;                                                          \
        LOCKDEP_INIT_MAP(&name##_lock_dep_map, #name, &name##_lock_key, 0); \
                lock = &per_cpu(name##_lock, i);                        \
                *lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;     \
        }                                                               \
+       register_hotcpu_notifier(&name##_lg_cpu_notifier);              \
+       get_online_cpus();                                              \
+       for_each_online_cpu(i)                                          \
+               cpu_set(i, name##_cpus);                                \
+       put_online_cpus();                                              \
  }                                                                     \
  EXPORT_SYMBOL(name##_lock_init);                                      \
                                                                        \
                                                                        \
  void name##_global_lock_online(void) {                                        \
        int i;                                                          \
-       preempt_disable();                                              \
+       spin_lock(&name##_cpu_lock);                                    \
        rwlock_acquire(&name##_lock_dep_map, 0, 0, _RET_IP_);           \
-       for_each_online_cpu(i) {                                        \
+       for_each_cpu(i, &name##_cpus) {                                 \
                arch_spinlock_t *lock;                                  \
                lock = &per_cpu(name##_lock, i);                        \
                arch_spin_lock(lock);                                   \
  void name##_global_unlock_online(void) {                              \
        int i;                                                          \
        rwlock_release(&name##_lock_dep_map, 1, _RET_IP_);              \
-       for_each_online_cpu(i) {                                        \
+       for_each_cpu(i, &name##_cpus) {                                 \
                arch_spinlock_t *lock;                                  \
                lock = &per_cpu(name##_lock, i);                        \
                arch_spin_unlock(lock);                                 \
        }                                                               \
-       preempt_enable();                                               \
+       spin_unlock(&name##_cpu_lock);                                  \
  }                                                                     \
  EXPORT_SYMBOL(name##_global_unlock_online);                           \
                                                                        \