From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yb1-f198.google.com (mail-yb1-f198.google.com [209.85.219.198]) by kanga.kvack.org (Postfix) with ESMTP id 6EF698E0001 for ; Wed, 26 Sep 2018 19:20:46 -0400 (EDT) Received: by mail-yb1-f198.google.com with SMTP id c6-v6so412004ybm.10 for ; Wed, 26 Sep 2018 16:20:46 -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 a15-v6sor149860ybs.149.2018.09.26.16.20.45 for (Google Transport Security); Wed, 26 Sep 2018 16:20:45 -0700 (PDT) Received: from mail-yw1-f49.google.com (mail-yw1-f49.google.com. [209.85.161.49]) by smtp.gmail.com with ESMTPSA id 129-v6sm140567ywm.87.2018.09.26.16.20.44 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 Sep 2018 16:20:44 -0700 (PDT) Received: by mail-yw1-f49.google.com with SMTP id v1-v6so314607ywv.6 for ; Wed, 26 Sep 2018 16:20:44 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20180924101150.23349-4-brgl@bgdev.pl> References: <20180924101150.23349-1-brgl@bgdev.pl> <20180924101150.23349-4-brgl@bgdev.pl> From: Kees Cook Date: Wed, 26 Sep 2018 16:13:39 -0700 Message-ID: Subject: Re: [PATCH v3 3/4] devres: provide devm_kstrdup_const() Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Bartosz Golaszewski 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@vger.kernel.org, LKML , Linux-MM On Mon, Sep 24, 2018 at 3:11 AM, 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. > > 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 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); > + > /** > * devm_kvasprintf - Allocate resource managed space and format a string > * 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 *dev, > 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()) -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