[patch 1/8] slab: introduce kzfree()

[Johannes Weiner <hannes@cmpxchg.org>]

[-- Attachment #1: slab-introduce-kzfree.patch --]
[-- Type: text/plain, Size: 1393 bytes --]

kzfree() is a wrapper for kfree() that additionally zeroes the
underlying memory before releasing it to the slab allocator.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
---
 include/linux/slab.h |    1 +
 mm/util.c            |   19 +++++++++++++++++++
 2 files changed, 20 insertions(+)

--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -127,6 +127,7 @@ int kmem_ptr_validate(struct kmem_cache 
 void * __must_check __krealloc(const void *, size_t, gfp_t);
 void * __must_check krealloc(const void *, size_t, gfp_t);
 void kfree(const void *);
+void kzfree(const void *);
 size_t ksize(const void *);
 
 /*
--- a/mm/util.c
+++ b/mm/util.c
@@ -129,6 +129,25 @@ void *krealloc(const void *p, size_t new
 }
 EXPORT_SYMBOL(krealloc);
 
+/**
+ * kzfree - like kfree but zero memory
+ * @p: object to free memory of
+ *
+ * The memory of the object @p points to is zeroed before freed.
+ * If @p is %NULL, kzfree() does nothing.
+ */
+void kzfree(const void *p)
+{
+	size_t ks;
+	void *mem = (void *)p;
+
+	if (unlikely(ZERO_OR_NULL_PTR(mem)))
+		return;
+	ks = ksize(mem);
+	memset(mem, 0, ks);
+	kfree(mem);
+}
+
 /*
  * strndup_user - duplicate an existing string from user space
  * @s: The string to duplicate