X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=lib%2Fstackdepot.c;h=53ad6c0831aebe6d3c9ec7cfc1387fa34ca7ea72;hb=7c31190bcfdbff225950902a9f226e4eb79ca94f;hp=654c9d87e83aac9da685d2626dc437f2be0ac95c;hpb=3addc4e3a7142fcb9782c1d8ab70c63ebbd6d803;p=deliverable%2Flinux.git

diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 654c9d87e83a..53ad6c0831ae 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -42,12 +42,14 @@
 
 #define DEPOT_STACK_BITS (sizeof(depot_stack_handle_t) * 8)
 
+#define STACK_ALLOC_NULL_PROTECTION_BITS 1
 #define STACK_ALLOC_ORDER 2 /* 'Slab' size order for stack depot, 4 pages */
 #define STACK_ALLOC_SIZE (1LL << (PAGE_SHIFT + STACK_ALLOC_ORDER))
 #define STACK_ALLOC_ALIGN 4
 #define STACK_ALLOC_OFFSET_BITS (STACK_ALLOC_ORDER + PAGE_SHIFT - \
 					STACK_ALLOC_ALIGN)
-#define STACK_ALLOC_INDEX_BITS (DEPOT_STACK_BITS - STACK_ALLOC_OFFSET_BITS)
+#define STACK_ALLOC_INDEX_BITS (DEPOT_STACK_BITS - \
+		STACK_ALLOC_NULL_PROTECTION_BITS - STACK_ALLOC_OFFSET_BITS)
 #define STACK_ALLOC_SLABS_CAP 1024
 #define STACK_ALLOC_MAX_SLABS \
 	(((1LL << (STACK_ALLOC_INDEX_BITS)) < STACK_ALLOC_SLABS_CAP) ? \
@@ -59,6 +61,7 @@ union handle_parts {
 	struct {
 		u32 slabindex : STACK_ALLOC_INDEX_BITS;
 		u32 offset : STACK_ALLOC_OFFSET_BITS;
+		u32 valid : STACK_ALLOC_NULL_PROTECTION_BITS;
 	};
 };
 
@@ -136,6 +139,7 @@ static struct stack_record *depot_alloc_stack(unsigned long *entries, int size,
 	stack->size = size;
 	stack->handle.slabindex = depot_index;
 	stack->handle.offset = depot_offset >> STACK_ALLOC_ALIGN;
+	stack->handle.valid = 1;
 	memcpy(stack->entries, entries, size * sizeof(unsigned long));
 	depot_offset += required_size;
 
@@ -210,10 +214,6 @@ depot_stack_handle_t depot_save_stack(struct stack_trace *trace,
 		goto fast_exit;
 
 	hash = hash_stack(trace->entries, trace->nr_entries);
-	/* Bad luck, we won't store this stack. */
-	if (hash == 0)
-		goto exit;
-
 	bucket = &stack_table[hash & STACK_HASH_MASK];
 
 	/*