From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it1-f198.google.com (mail-it1-f198.google.com [209.85.166.198]) by kanga.kvack.org (Postfix) with ESMTP id D274C8E0001 for ; Thu, 27 Sep 2018 04:53:22 -0400 (EDT) Received: by mail-it1-f198.google.com with SMTP id y73-v6so199663ita.2 for ; Thu, 27 Sep 2018 01:53:22 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id g1-v6sor685942jaj.53.2018.09.27.01.53.21 for (Google Transport Security); Thu, 27 Sep 2018 01:53:21 -0700 (PDT) MIME-Version: 1.0 References: <20180924101150.23349-1-brgl@bgdev.pl> <20180924101150.23349-4-brgl@bgdev.pl> In-Reply-To: From: Bartosz Golaszewski Date: Thu, 27 Sep 2018 10:53:09 +0200 Message-ID: Subject: Re: [PATCH v3 3/4] devres: provide devm_kstrdup_const() Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Kees Cook Cc: Michael Turquette , Stephen Boyd , Greg Kroah-Hartman , "Rafael J . Wysocki" , Arend van Spriel , Ulf Hansson , Bjorn Helgaas , Vivek Gautam , Robin Murphy , Joe Perches , Heikki Krogerus , Andrew Morton , Mike Rapoport , Michal Hocko , Al Viro , Jonathan Corbet , Roman Gushchin , Huang Ying , Bjorn Andersson , Arnd Bergmann , Andy Shevchenko , linux-clk , Linux Kernel Mailing List , linux-mm@kvack.org czw., 27 wrz 2018 o 01:20 Kees Cook napisa=C5=82(a)= : > > On Mon, Sep 24, 2018 at 3:11 AM, Bartosz Golaszewski wrot= e: > > 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. > > > > Also provide a corresponding version of devm_kfree(). > > > > Signed-off-by: Bartosz Golaszewski > > Reviewed-by: Bjorn Andersson > > --- > > drivers/base/devres.c | 38 ++++++++++++++++++++++++++++++++++++++ > > include/linux/device.h | 3 +++ > > 2 files changed, 41 insertions(+) > > > > diff --git a/drivers/base/devres.c b/drivers/base/devres.c > > index 438c91a43508..48185d57bc5b 100644 > > --- a/drivers/base/devres.c > > +++ b/drivers/base/devres.c > > @@ -11,6 +11,8 @@ > > #include > > #include > > > > +#include > > + > > #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 duplicatio= n > > + * @dev: device for which to duplicate the string > > + * @s: the string to duplicate > > + * @gfp: the GFP mask used in the kmalloc() call when allocating memor= y > > + * > > + * 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 t= o > > + * 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); > > + > > /** > > * devm_kvasprintf - Allocate resource managed space and format a stri= ng > > * into that. > > @@ -895,6 +919,20 @@ void devm_kfree(struct device *dev, const void *p) > > } > > EXPORT_SYMBOL_GPL(devm_kfree); > > > > +/** > > + * devm_kfree_const - Resource managed conditional kfree > > + * @dev: device this memory belongs to > > + * @p: memory to free > > + * > > + * Function calls devm_kfree only if @p is not in .rodata section. > > + */ > > +void devm_kfree_const(struct device *dev, const void *p) > > +{ > > + if (!is_kernel_rodata((unsigned long)p)) > > + devm_kfree(dev, p); > > +} > > +EXPORT_SYMBOL(devm_kfree_const); > > + > > /** > > * devm_kmemdup - Resource-managed kmemdup > > * @dev: Device this memory belongs to > > diff --git a/include/linux/device.h b/include/linux/device.h > > index 33f7cb271fbb..79ccc6eb0975 100644 > > --- a/include/linux/device.h > > +++ b/include/linux/device.h > > @@ -693,7 +693,10 @@ static inline void *devm_kcalloc(struct device *de= v, > > return devm_kmalloc_array(dev, n, size, flags | __GFP_ZERO); > > } > > extern void devm_kfree(struct device *dev, const void *p); > > +extern void devm_kfree_const(struct device *dev, const void *p); > > With devm_kfree and devm_kfree_const both taking "const", how are > devm_kstrdup_const() and devm_kfree_const() going to be correctly > paired at compile time? (i.e. I wasn't expecting the prototype change > to devm_kfree()) > I guess the same as with kfree() and kfree_const() which both take const void * as argument - it's up to users to only use devm_kfree_const() on resources allocated with devm_kstrdup_const(). Bart > -Kees > > > 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, > > gfp_t gfp); > > > > -- > > 2.18.0 > > > > > > -- > Kees Cook > Pixel Security