Re: [RESEND PATCH v6 3/4] devres: provide devm_kstrdup_const()

Greg Kroah-Hartman
2018-10-16T10:50:59Z

On Sun, Oct 14, 2018 at 05:20:09PM +0200, Bartosz Golaszewski wrote:
> 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>
> ---
> drivers/base/devres.c | 31 +++++++++++++++++++++++++++++++
> include/linux/device.h | 2 ++
> 2 files changed, 33 insertions(+)
>
> diff --git a/drivers/base/devres.c b/drivers/base/devres.c
> index 438c91a43508..00c70f0fcdcd 100644
> --- a/drivers/base/devres.c
> +++ b/drivers/base/devres.c
> @@ -11,6 +11,8 @@
> #include <linux/slab.h>
> #include <linux/percpu.h>
>
> +#include <asm/sections.h>
> +
> #include "base.h"
>
> struct devres_node {
> @@ -822,6 +824,28 @@ char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp)
> }
> 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(devm_kstrdup_const);

This should be EXPORT_SYMBOL_GPL() to match the rest of the file. I'll
go fix that up when I apply it.

thanks,

greg k-h