powerpc/mm: Fix a AB->BA deadlock scenario with nohash MMU context lock

[deliverable/linux.git] / arch / powerpc / mm / mmu_context_nohash.c

diff --git a/arch/powerpc/mm/mmu_context_nohash.c b/arch/powerpc/mm/mmu_context_nohash.c
index c42858780cbd239565289bb572b5cbf2198744e2..8343986809c03fe2b3e952e411ec31a611fffe8b 100644 (file)
--- a/arch/powerpc/mm/mmu_context_nohash.c
+++ b/arch/powerpc/mm/mmu_context_nohash.c
@@ -46,7 +46,7 @@ static unsigned int next_context, nr_free_contexts;
 static unsigned long *context_map;
 static unsigned long *stale_map[NR_CPUS];
 static struct mm_struct **context_mm;
-static spinlock_t context_lock = SPIN_LOCK_UNLOCKED;
+static DEFINE_SPINLOCK(context_lock);
 
 #define CTX_MAP_SIZE   \
        (sizeof(unsigned long) * (last_context / BITS_PER_LONG + 1))
@@ -276,6 +276,7 @@ int init_new_context(struct task_struct *t, struct mm_struct *mm)
  */
 void destroy_context(struct mm_struct *mm)
 {
+       unsigned long flags;
        unsigned int id;
 
        if (mm->context.id == MMU_NO_CONTEXT)
@@ -283,7 +284,7 @@ void destroy_context(struct mm_struct *mm)
 
        WARN_ON(mm->context.active != 0);
 
-       spin_lock(&context_lock);
+       spin_lock_irqsave(&context_lock, flags);
        id = mm->context.id;
        if (id != MMU_NO_CONTEXT) {
                __clear_bit(id, context_map);
@@ -294,7 +295,7 @@ void destroy_context(struct mm_struct *mm)
                context_mm[id] = NULL;
                nr_free_contexts++;
        }
-       spin_unlock(&context_lock);
+       spin_unlock_irqrestore(&context_lock, flags);
 }
 
 #ifdef CONFIG_SMP