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Date: Fri, 5 Apr 2024 08:09:12 +0200
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Arnd Bergmann <arnd@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>, Luis Chamberlain <mcgrof@kernel.org>,
	linux-modules@vger.kernel.org,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Jens Axboe <axboe@kernel.dk>,
	"Ricardo B. Marliere" <ricardo@marliere.net>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] [v3] module: don't ignore sysfs_create_link() failures
Message-ID: <2024040558-animation-express-1ae1@gregkh>
References: <20240326145733.3413024-1-arnd@kernel.org>
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In-Reply-To: <20240326145733.3413024-1-arnd@kernel.org>

On Tue, Mar 26, 2024 at 03:57:18PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The sysfs_create_link() return code is marked as __must_check, but the
> module_add_driver() function tries hard to not care, by assigning the
> return code to a variable. When building with 'make W=1', gcc still
> warns because this variable is only assigned but not used:
> 
> drivers/base/module.c: In function 'module_add_driver':
> drivers/base/module.c:36:6: warning: variable 'no_warn' set but not used [-Wunused-but-set-variable]
> 
> Rework the code to properly unwind and return the error code to the
> caller. My reading of the original code was that it tries to
> not fail when the links already exist, so keep ignoring -EEXIST
> errors.
> 
> Cc: Luis Chamberlain <mcgrof@kernel.org>
> Cc: linux-modules@vger.kernel.org
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Fixes: e17e0f51aeea ("Driver core: show drivers in /sys/module/")
> See-also: 4a7fb6363f2d ("add __must_check to device management code")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> v3: make error handling stricter, add unwinding,
>      fix build fail with CONFIG_MODULES=n
> v2: rework to actually handle the error. I have not tested the
>     error handling beyond build testing, so please review carefully.
> ---
>  drivers/base/base.h   |  9 ++++++---
>  drivers/base/bus.c    |  9 ++++++++-
>  drivers/base/module.c | 42 +++++++++++++++++++++++++++++++-----------
>  3 files changed, 45 insertions(+), 15 deletions(-)

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>