linux-kernel - [PATCH v3 0/6] gpio: notify user-space about config changes in the kernel

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Message-Id: <20241015-gpio-notify-in-kernel-events-v3-0-9edf05802271@linaro.org>
Date: Tue, 15 Oct 2024 12:56:12 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Linus Walleij <linus.walleij@...aro.org>, 
 Bartosz Golaszewski <brgl@...ev.pl>, Kent Gibson <warthog618@...il.com>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH v3 0/6] gpio: notify user-space about config changes in the
 kernel

We currently only emit events on changed line config to user-space on
changes made from user-space. Users have no way of getting notified
about in-kernel changes. This series improves the situation and also
contains a couple other related improvements.

This is a reworked approach which gets and stores as much info (all of
it actually, except for the pinctrl state) the moment the event occurrs
but moves the actual queueing of the event on the kfifo to a dedicated
high-priority, ordered workqueue.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
Changes in v3:
- don't reach into pinctrl if the USED flag is already set
- reword the comment from patch 5 and move it one patch back
- don't abandon emitting the event if the GPIO chip is gone by the time
  the work is executed, just don't reach into pinctrl and return
  whatever data we already had
- Link to v2: https://lore.kernel.org/r/20241010-gpio-notify-in-kernel-events-v2-0-b560411f7c59@linaro.org

Changes in v2:
- put all line-info events emitting on a workqueue to allow queueing
  them from atomic context
- switch the notifier type used for emitting info events to atomic
- add a patch notifying user-space about drivers requesting their own
  descs
- drop patches that were picked up
- Link to v1: https://lore.kernel.org/r/20241004-gpio-notify-in-kernel-events-v1-0-8ac29e1df4fe@linaro.org

---
Bartosz Golaszewski (6):
      gpiolib: notify user-space when a driver requests its own desc
      gpio: cdev: prepare gpio_desc_to_lineinfo() for being called from atomic
      gpiolib: add a per-gpio_device line state notification workqueue
      gpio: cdev: put emitting the line state events on a workqueue
      gpiolib: switch the line state notifier to atomic
      gpiolib: notify user-space about in-kernel line state changes

 drivers/gpio/gpiolib-cdev.c | 127 +++++++++++++++++++++++++++++++++-----------
 drivers/gpio/gpiolib.c      |  79 +++++++++++++++++++++++----
 drivers/gpio/gpiolib.h      |   8 ++-
 3 files changed, 172 insertions(+), 42 deletions(-)
---
base-commit: b852e1e7a0389ed6168ef1d38eb0bad71a6b11e8
change-id: 20240924-gpio-notify-in-kernel-events-07cd912153e8

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@...aro.org>