[PATCH 5/6] slab: Annotate slab

[Steve VanDeBogart]

Valgrind annotations for the slab allocator:  Malloc-like and free-like
for cache_alloc and free.  Telling Valgrind a region is free-like clears
all the valid bits, so slabs with constructors need different treatment;
tell Valgrind about slab objects when first constructed and free them
when the slab is destroyed.

Signed-off-by: Steve VanDeBogart <vandebo-lkml@xxxxxxxxxxx>
---

Index: linux-2.6.27-rc5/mm/slab.c
===================================================================
--- linux-2.6.27-rc5.orig/mm/slab.c	2008-08-29 14:24:25.000000000 -0700
+++ linux-2.6.27-rc5/mm/slab.c	2008-08-29 14:24:42.000000000 -0700
@@ -111,6 +111,7 @@
 #include	<linux/rtmutex.h>
 #include	<linux/reciprocal_div.h>
 #include	<linux/debugobjects.h>
+#include	<linux/memcheck.h>

 #include	<asm/cacheflush.h>
 #include	<asm/tlbflush.h>
@@ -1906,6 +1907,8 @@
 	int i;
 	for (i = 0; i < cachep->num; i++) {
 		void *objp = index_to_obj(cachep, slabp, i);
+		if (cachep->ctor)
+			VALGRIND_FREELIKE_BLOCK(objp, 0);

 		if (cachep->flags & SLAB_POISON) {
 #ifdef CONFIG_DEBUG_PAGEALLOC
@@ -1932,6 +1935,15 @@
 #else
 static void slab_destroy_debugcheck(struct kmem_cache *cachep, struct slab *slabp)
 {
+#ifdef CONFIG_VALGRIND_SUPPORT
+	int i;
+	if (cachep->ctor) {
+		for (i = 0; i < cachep->num; i++) {
+			void *objp = index_to_obj(cachep, slabp, i);
+			VALGRIND_FREELIKE_BLOCK(objp, 0);
+		}
+	}
+#endif
 }
 #endif

@@ -2635,6 +2647,9 @@

 	for (i = 0; i < cachep->num; i++) {
 		void *objp = index_to_obj(cachep, slabp, i);
+		if (cachep->ctor)
+			VALGRIND_MALLOCLIKE_BLOCK(objp, cachep->buffer_size,
+							0, 0);
 #if DEBUG
 		/* need to poison the objs? */
 		if (cachep->flags & SLAB_POISON)
@@ -3466,6 +3481,8 @@
 	objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller);
 	prefetchw(objp);

+	if (!cachep->ctor)
+		VALGRIND_MALLOCLIKE_BLOCK(objp, cachep->buffer_size, 0, 0);
 	if (unlikely((flags & __GFP_ZERO) && objp))
 		memset(objp, 0, obj_size(cachep));

@@ -3578,6 +3595,9 @@
 {
 	struct array_cache *ac = cpu_cache_get(cachep);

+	if (!cachep->ctor)
+		VALGRIND_FREELIKE_BLOCK(objp, 0);
+
 	check_irq_off();
 	objp = cache_free_debugcheck(cachep, objp, __builtin_return_address(0));

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