From: Kent Gibson <warthog618@gmail.com>
To: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Cc: Linus Walleij <linusw@kernel.org>,
Bartosz Golaszewski <brgl@kernel.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Adrian Ambrozewicz <aambrozewicz@nvidia.com>,
linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH v3 5/5] gpio: cdev: don't overwrite the whole flags field when configuring lines
Date: Fri, 13 Nov 2026 11:19:43 +0800 [thread overview]
Message-ID: <20261113031943.GA39484@rigel> (raw)
In-Reply-To: <20261110-gpio-desc-flags-atomic-v3-5-2f463bce8086@oss.qualcomm.com>
On Tue, Nov 10, 2026 at 02:47:05PM +0100, Bartosz Golaszewski wrote:
> linehandle_flags_to_desc_flags() and
> gpio_v2_line_config_flags_to_desc_flags() read the flags word with
> READ_ONCE(), modify the local copy and write it back with WRITE_ONCE().
>
> The per-request config_mutex does not exclude sysfs, the irq core or
> drivers touching the same descriptor, so bits they set or clear
> concurrently can be lost.
>
> Build the mask of bits owned by the line configuration and their new
> values locally and apply them with gpiod_update_flags(). The whole
> group changes in a single atomic step.
>
> While at it: rename the functions whose semantics changed from
> "conversion" to "flags update" accordingly.
>
> Cc: stable@vger.kernel.org
> Fixes: b7adfb6076ff ("gpio: cdev: update flags at once when reconfiguring from user-space")
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
> ---
Reviewed-by: Kent Gibson <warthog618@gmail.com>
for the series.
Cheers,
Kent.
prev parent reply other threads:[~2026-11-13 3:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-10 13:47 [PATCH v3 0/5] gpiolib: improve concurrent access to the flags field of struct gpio_desc Bartosz Golaszewski
2026-11-10 13:47 ` [PATCH v3 1/5] gpiolib: don't overwrite the entire flags field in gpiod_get_direction() Bartosz Golaszewski
2026-11-10 13:47 ` [PATCH v3 2/5] gpio: shared: use atomic set_bit() for descriptor flags Bartosz Golaszewski
2026-11-10 13:47 ` [PATCH v3 4/5] gpiolib: don't overwrite the entire flags field in gpiod_free_commit() Bartosz Golaszewski
2026-11-10 13:47 ` [PATCH v3 5/5] gpio: cdev: don't overwrite the whole flags field when configuring lines Bartosz Golaszewski
2026-11-13 3:19 ` Kent Gibson [this message]
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