[SPARC64]: Bulletproof MMU context locking.

1) Always spin_lock_init() in init_context().  The caller essentially
   clears it out, or copies the mm info from the parent.  In both
   cases we need to explicitly initialize the spinlock.

2) Always do explicit IRQ disabling while taking mm->context.lock
   and ctx_alloc_lock.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc64/mm/init.c b/arch/sparc64/mm/init.c
index 9bbd0bf64af0f44fabfc1f2857256f71b7556a5f..a63939347b3d4ed4d90da6603770a1ad59585b21 100644 (file)
--- a/arch/sparc64/mm/init.c
+++ b/arch/sparc64/mm/init.c
@@ -639,9 +639,10 @@ void get_new_mmu_context(struct mm_struct *mm)
 {
        unsigned long ctx, new_ctx;
        unsigned long orig_pgsz_bits;
+       unsigned long flags;
        int new_version;
 
-       spin_lock(&ctx_alloc_lock);
+       spin_lock_irqsave(&ctx_alloc_lock, flags);
        orig_pgsz_bits = (mm->context.sparc64_ctx_val & CTX_PGSZ_MASK);
        ctx = (tlb_context_cache + 1) & CTX_NR_MASK;
        new_ctx = find_next_zero_bit(mmu_context_bmap, 1 << CTX_NR_BITS, ctx);
@@ -677,7 +678,7 @@ void get_new_mmu_context(struct mm_struct *mm)
 out:
        tlb_context_cache = new_ctx;
        mm->context.sparc64_ctx_val = new_ctx | orig_pgsz_bits;
-       spin_unlock(&ctx_alloc_lock);
+       spin_unlock_irqrestore(&ctx_alloc_lock, flags);
 
        if (unlikely(new_version))
                smp_new_mmu_context_version();

diff --git a/arch/sparc64/mm/tsb.c b/arch/sparc64/mm/tsb.c
index 534ac2819892f96daebef6fd4d46b86b7ddc8c4f..f36799b7152ce47470c93125127bb3a000281492 100644 (file)
--- a/arch/sparc64/mm/tsb.c
+++ b/arch/sparc64/mm/tsb.c
@@ -354,6 +354,7 @@ void tsb_grow(struct mm_struct *mm, unsigned long rss, gfp_t gfp_flags)
 
 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 {
+       spin_lock_init(&mm->context.lock);
 
        mm->context.sparc64_ctx_val = 0UL;
 

diff --git a/include/asm-sparc64/mmu_context.h b/include/asm-sparc64/mmu_context.h
index 4be40c58e3c15dc9592cc69302c1b07e5acf9637..ca36ea96f64bc8694baed2ae40feb1557bff6545 100644 (file)
--- a/include/asm-sparc64/mmu_context.h
+++ b/include/asm-sparc64/mmu_context.h
@@ -67,14 +67,14 @@ extern void __flush_tlb_mm(unsigned long, unsigned long);
 /* Switch the current MM context.  Interrupts are disabled.  */
 static inline void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, struct task_struct *tsk)
 {
-       unsigned long ctx_valid;
+       unsigned long ctx_valid, flags;
        int cpu;
 
-       spin_lock(&mm->context.lock);
+       spin_lock_irqsave(&mm->context.lock, flags);
        ctx_valid = CTX_VALID(mm->context);
        if (!ctx_valid)
                get_new_mmu_context(mm);
-       spin_unlock(&mm->context.lock);
+       spin_unlock_irqrestore(&mm->context.lock, flags);
 
        if (!ctx_valid || (old_mm != mm)) {
                load_secondary_context(mm);