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devres: provide devm_kstrdup_const()

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Provide a resource managed version of kstrdup_const(). This variant
internally calls devm_kstrdup() on pointers that are outside of
.rodata section and returns the string as is otherwise.

Make devm_kfree() check if the passed pointer doesn't point to .rodata
and if so - don't actually destroy the resource.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Bartosz Golaszewski 2018-10-14 17:20:09 +02:00 • committed by Greg Kroah-Hartman
parent 59c3f82ad1
commit 09d1ea1c73
2 changed files with 33 additions and 0 deletions
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31
drivers/base/devres.c
View file

@ -11,6 +11,8 @@
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/percpu.h> #include <linux/percpu.h>
#include <asm/sections.h>
#include "base.h" #include "base.h"
struct devres_node { struct devres_node {
@ -822,6 +824,28 @@ char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp)
} }
EXPORT_SYMBOL_GPL(devm_kstrdup); EXPORT_SYMBOL_GPL(devm_kstrdup);
/**
* devm_kstrdup_const - resource managed conditional string duplication
* @dev: device for which to duplicate the string
* @s: the string to duplicate
* @gfp: the GFP mask used in the kmalloc() call when allocating memory
*
* Strings allocated by devm_kstrdup_const will be automatically freed when
* the associated device is detached.
*
* RETURNS:
* Source string if it is in .rodata section otherwise it falls back to
* devm_kstrdup.
*/
const char *devm_kstrdup_const(struct device *dev, const char *s, gfp_t gfp)
{
if (is_kernel_rodata((unsigned long)s))
return s;
return devm_kstrdup(dev, s, gfp);
}
EXPORT_SYMBOL_GPL(devm_kstrdup_const);
/** /**
* devm_kvasprintf - Allocate resource managed space and format a string * devm_kvasprintf - Allocate resource managed space and format a string
* into that. * into that.
@ -889,6 +913,13 @@ void devm_kfree(struct device *dev, const void *p)
{ {
int rc; int rc;
/*
* Special case: pointer to a string in .rodata returned by
* devm_kstrdup_const().
*/
if (unlikely(is_kernel_rodata((unsigned long)p)))
return;
rc = devres_destroy(dev, devm_kmalloc_release, rc = devres_destroy(dev, devm_kmalloc_release,
devm_kmalloc_match, (void *)p); devm_kmalloc_match, (void *)p);
WARN_ON(rc); WARN_ON(rc);

2
include/linux/device.h
View file

@ -696,6 +696,8 @@ static inline void *devm_kcalloc(struct device *dev,
} }
extern void devm_kfree(struct device *dev, const void *p); extern void devm_kfree(struct device *dev, const void *p);
extern char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp) __malloc; extern char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp) __malloc;
extern const char *devm_kstrdup_const(struct device *dev,
const char *s, gfp_t gfp);
extern void *devm_kmemdup(struct device *dev, const void *src, size_t len, extern void *devm_kmemdup(struct device *dev, const void *src, size_t len,
gfp_t gfp); gfp_t gfp);