Received-SPF: pass (google.com: domain of linux-kernel+bounces-65825-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Date: Wed, 14 Feb 2024 10:44:36 -0800
From: "Paul E. McKenney" <paulmck@kernel.org>
To: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Linus Walleij <linus.walleij@linaro.org>,
	Kent Gibson <warthog618@gmail.com>, Alex Elder <elder@linaro.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Wolfram Sang <wsa@the-dreams.de>, Mark Brown <broonie@kernel.org>,
	Dan Carpenter <dan.carpenter@linaro.org>,
	linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Subject: Re: [PATCH v2 0/4] gpio: fix SRCU bugs
Message-ID: <4a08c610-c249-4b56-b09c-09e1fd07f723@paulmck-laptop>
Reply-To: paulmck@kernel.org
References: <20240214084419.6194-1-brgl@bgdev.pl>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20240214084419.6194-1-brgl@bgdev.pl>

On Wed, Feb 14, 2024 at 09:44:15AM +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> Here are four fixes to some bugs in recent SRCU changes. The first one fixes
> an actual race condition. The other three just make lockdep happy.

For 1/4-3/4:

Acked-by: Paul E. McKenney <paulmck@kernel.org>

For 4/4, you are playing with fire, but I will assume that you know what
you are doing.  ;-)

							Thanx, Paul

> v1 -> v2:
> - use srcu_dereference() instead of rcu_dereference_protected() as
>   advised by Paul
> - add a patch using rcu_dereference_check(..., 1) in deprecated
>   interfaces that return the address of the RCU-protected chip structure
>   to external users (who shouldn't use it anyway but well...)
> - pick up review tags for patches 1/4 and 2/4
> 
> Bartosz Golaszewski (4):
>   gpio: take the SRCU read lock in gpiod_hog()
>   gpio: cdev: use correct pointer accessors with SRCU
>   gpio: use srcu_dereference() with SRCU-protected pointers
>   gpio: don't let lockdep complain about inherently dangerous RCU usage
> 
>  drivers/gpio/gpiolib-cdev.c  | 25 ++++++++++++-------------
>  drivers/gpio/gpiolib-sysfs.c |  5 +++--
>  drivers/gpio/gpiolib.c       | 32 ++++++++++++++++++--------------
>  drivers/gpio/gpiolib.h       |  3 ++-
>  4 files changed, 35 insertions(+), 30 deletions(-)
> 
> -- 
> 2.40.1
>