linux-kernel - [PATCH 0/2] gpiolib: use a read-write semaphore to protect the GPIO device list

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Message-Id: <20231221184316.24506-1-brgl@bgdev.pl>
Date: Thu, 21 Dec 2023 19:43:14 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Linus Walleij <linus.walleij@...aro.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Kent Gibson <warthog618@...il.com>
Cc: linux-gpio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH 0/2] gpiolib: use a read-write semaphore to protect the GPIO device list

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

I'm still figuring out how to keep GPIO descriptors coherent while
(mostly) lockless. In the meantime, I found a potential race-condition
during GPIO descriptor lookup and also figured that the correct way to
protect the GPIO device list is actually a read-write semaphore as we're
not modifying the list very often and readers should be able to iterate
over it concurrently.

Bartosz Golaszewski (2):
  gpiolib: replace the GPIO device mutex with a read-write semaphore
  gpiolib: pin GPIO devices in place during descriptor lookup

 drivers/gpio/gpiolib-sysfs.c |  2 +-
 drivers/gpio/gpiolib.c       | 58 ++++++++++++++++++++----------------
 drivers/gpio/gpiolib.h       |  2 +-
 3 files changed, 34 insertions(+), 28 deletions(-)

-- 
2.40.1