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Message-Id: <20131011131138.3bc5b2acf60df3a5d79d0d24@linux-foundation.org>
Date: Fri, 11 Oct 2013 13:11:38 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Joe Perches <joe@...ches.com>
Cc: Tejun Heo <tj@...nel.org>, Greg KH <gregkh@...uxfoundation.org>,
LKML <linux-kernel@...r.kernel.org>,
Sangjung Woo <sangjung.woo@...sung.com>
Subject: Re: [RFC PATCH] device: Add kernel standard devm_k.alloc functions
On Tue, 08 Oct 2013 22:32:27 -0700 Joe Perches <joe@...ches.com> wrote:
> Currently, devm_ managed memory only supports kzalloc.
>
> Convert the devm_kzalloc implementation to devm_kmalloc
> and remove the complete memset to 0 but still set the
> initial struct devres header and whatever padding before
> data to 0.
>
> Add the other normal alloc variants as static inlines with
> __GFP_ZERO added to the gfp flag where appropriate:
>
> devm_kzalloc
> devm_kcalloc
> devm_kmalloc_array
>
> Add gfp.h to device.h for the newly added static inlines.
>
> ...
>
> --- a/drivers/base/devres.c
> +++ b/drivers/base/devres.c
> @@ -91,7 +91,8 @@ static __always_inline struct devres * alloc_dr(dr_release_t release,
> if (unlikely(!dr))
> return NULL;
>
> - memset(dr, 0, tot_size);
> + memset(dr, 0, offsetof(struct devres, data));
Well, this does make some assumptions about devres layout. It would
have been cleaner to do
memset(&dr.node, 0, sizeof(dr.node));
but whatever.
I made some changelog changes.
I agree that including devm_kmalloc_array() might be going a bit far
(it's the lack of devm_kmalloc which matters most). But
devm_kmalloc_array() is inlined and is hence basically cost-free until
someone actually uses it.
From: Joe Perches <joe@...ches.com>
Subject: devres: add kernel standard devm_k.alloc functions
Currently, devm_ managed memory only supports kzalloc.
Convert the devm_kzalloc implementation to devm_kmalloc and remove the
complete memset to 0 but still set the initial struct devres header and
whatever padding before data to 0.
Add the other normal alloc variants as static inlines with __GFP_ZERO
added to the gfp flag where appropriate:
devm_kzalloc
devm_kcalloc
devm_kmalloc_array
Add gfp.h to device.h for the newly added static inlines.
akpm: the current API forces us to replace kmalloc() with kzalloc() when
performing devm_ conversions. This adds a relatively minor overhead.
More significantly, it will defeat kmemcheck used-uninitialized checking,
and for a particular driver, losing used-uninitialised checking for their
core controlling data structures will significantly degrade kmemcheck
usefulness.
Signed-off-by: Joe Perches <joe@...ches.com>
Cc: Tejun Heo <tj@...nel.org>
Cc: Greg KH <gregkh@...uxfoundation.org>
Cc: Sangjung Woo <sangjung.woo@...sung.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---
drivers/base/devres.c | 27 ++++++++++++++++-----------
include/linux/device.h | 21 +++++++++++++++++++--
2 files changed, 35 insertions(+), 13 deletions(-)
diff -puN drivers/base/devres.c~device-add-kernel-standard-devm_kalloc-functions drivers/base/devres.c
--- a/drivers/base/devres.c~device-add-kernel-standard-devm_kalloc-functions
+++ a/drivers/base/devres.c
@@ -91,7 +91,8 @@ static __always_inline struct devres * a
if (unlikely(!dr))
return NULL;
- memset(dr, 0, tot_size);
+ memset(dr, 0, offsetof(struct devres, data));
+
INIT_LIST_HEAD(&dr->node.entry);
dr->node.release = release;
return dr;
@@ -745,58 +746,62 @@ void devm_remove_action(struct device *d
EXPORT_SYMBOL_GPL(devm_remove_action);
/*
- * Managed kzalloc/kfree
+ * Managed kmalloc/kfree
*/
-static void devm_kzalloc_release(struct device *dev, void *res)
+static void devm_kmalloc_release(struct device *dev, void *res)
{
/* noop */
}
-static int devm_kzalloc_match(struct device *dev, void *res, void *data)
+static int devm_kmalloc_match(struct device *dev, void *res, void *data)
{
return res == data;
}
/**
- * devm_kzalloc - Resource-managed kzalloc
+ * devm_kmalloc - Resource-managed kmalloc
* @dev: Device to allocate memory for
* @size: Allocation size
* @gfp: Allocation gfp flags
*
- * Managed kzalloc. Memory allocated with this function is
+ * Managed kmalloc. Memory allocated with this function is
* automatically freed on driver detach. Like all other devres
* resources, guaranteed alignment is unsigned long long.
*
* RETURNS:
* Pointer to allocated memory on success, NULL on failure.
*/
-void * devm_kzalloc(struct device *dev, size_t size, gfp_t gfp)
+void * devm_kmalloc(struct device *dev, size_t size, gfp_t gfp)
{
struct devres *dr;
/* use raw alloc_dr for kmalloc caller tracing */
- dr = alloc_dr(devm_kzalloc_release, size, gfp);
+ dr = alloc_dr(devm_kmalloc_release, size, gfp);
if (unlikely(!dr))
return NULL;
+ /*
+ * This is named devm_kzalloc_release for historical reasons
+ * The initial implementation did not support kmalloc, only kzalloc
+ */
set_node_dbginfo(&dr->node, "devm_kzalloc_release", size);
devres_add(dev, dr->data);
return dr->data;
}
-EXPORT_SYMBOL_GPL(devm_kzalloc);
+EXPORT_SYMBOL_GPL(devm_kmalloc);
/**
* devm_kfree - Resource-managed kfree
* @dev: Device this memory belongs to
* @p: Memory to free
*
- * Free memory allocated with devm_kzalloc().
+ * Free memory allocated with devm_kmalloc().
*/
void devm_kfree(struct device *dev, void *p)
{
int rc;
- rc = devres_destroy(dev, devm_kzalloc_release, devm_kzalloc_match, p);
+ rc = devres_destroy(dev, devm_kmalloc_release, devm_kmalloc_match, p);
WARN_ON(rc);
}
EXPORT_SYMBOL_GPL(devm_kfree);
diff -puN include/linux/device.h~device-add-kernel-standard-devm_kalloc-functions include/linux/device.h
--- a/include/linux/device.h~device-add-kernel-standard-devm_kalloc-functions
+++ a/include/linux/device.h
@@ -26,6 +26,7 @@
#include <linux/atomic.h>
#include <linux/ratelimit.h>
#include <linux/uidgid.h>
+#include <linux/gfp.h>
#include <asm/device.h>
struct device;
@@ -602,8 +603,24 @@ extern void devres_close_group(struct de
extern void devres_remove_group(struct device *dev, void *id);
extern int devres_release_group(struct device *dev, void *id);
-/* managed kzalloc/kfree for device drivers, no kmalloc, always use kzalloc */
-extern void *devm_kzalloc(struct device *dev, size_t size, gfp_t gfp);
+/* managed devm_k.alloc/kfree for device drivers */
+extern void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp);
+static inline void *devm_kzalloc(struct device *dev, size_t size, gfp_t gfp)
+{
+ return devm_kmalloc(dev, size, gfp | __GFP_ZERO);
+}
+static inline void *devm_kmalloc_array(struct device *dev,
+ size_t n, size_t size, gfp_t flags)
+{
+ if (size != 0 && n > SIZE_MAX / size)
+ return NULL;
+ return devm_kmalloc(dev, n * size, flags);
+}
+static inline void *devm_kcalloc(struct device *dev,
+ size_t n, size_t size, gfp_t flags)
+{
+ return devm_kmalloc_array(dev, n, size, flags | __GFP_ZERO);
+}
extern void devm_kfree(struct device *dev, void *p);
void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res);
_
--
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