From: Vincent Pelletier <plr.vincent@gmail.com>
To: linux-gpio@vger.kernel.org
Cc: Simon Guinot <simon.guinot@sequanux.org>
Subject: gpio-f7188x: Fix concurrent GPIO accesses (and minor improvements)
Date: Thu, 20 Aug 2015 20:03:25 +0200 [thread overview]
Message-ID: <1440093809-18234-1-git-send-email-plr.vincent@gmail.com> (raw)
Hello,
Making intensive use of the GPIOs on this SuperIO chip, I triggered a race
condition causing apparently the wrong GPIO pins to be modified (and likely
read) randomly.
For some reason (unclear to me, I'm not used at all to kernel API),
request_muxed_region/release_region as it is used in this driver is not
sufficient to serialize accesses.
Also, reading other drivers for the same chip, I see a different pattern:
rather than accessing GPIO registers through the common IO region, this
region is only used for device discovery. From there, per-function base
address is retrieved, and that IO region gets requested once.
So I fixed the concurrent access by:
- using the same access pattern as in other drivers
- adding mutexes around IO region accesses
Once this was done and I got a bit more comfortable with this driver, chip and
gpiolib, I continued and fixed 3 minor issues/lacks.
Regards,
--
Vincent Pelletier
next reply other threads:[~2015-08-20 18:03 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-20 18:03 Vincent Pelletier [this message]
2015-08-20 18:03 ` [1/4] gpio: gpio-f7188x: Use mutex for access serialisation Vincent Pelletier
2015-08-20 18:03 ` [2/4] gpio: gpio-f7188x: GPIO bank 0 bit 0 is not available on f71869a Vincent Pelletier
2015-08-20 18:03 ` [3/4] gpio: gpio-f7188x: "get" should retrieve sensed level when available Vincent Pelletier
2015-08-20 18:03 ` [4/4] gpio: gpio-f7188x: Implement get_direction Vincent Pelletier
2015-08-21 17:52 ` [1/4] gpio: gpio-f7188x: Use mutex for access serialisation Simon Guinot
2015-08-21 20:48 ` Vincent Pelletier
2015-08-22 17:04 ` Vincent Pelletier
2015-09-03 18:05 ` Vincent Pelletier
2015-09-04 7:39 ` Simon Guinot
2015-09-09 22:01 ` Simon Guinot
2015-09-09 22:15 ` [PATCH] kernel/resource.c: fix muxed resource handling in __request_region() Simon Guinot
2016-02-19 21:10 ` Vincent Pelletier
2016-02-19 23:25 ` Jesse Barnes
2016-02-20 17:11 ` Linus Torvalds
2016-02-20 22:15 ` Jesse Barnes
2016-02-20 22:15 ` Jesse Barnes
2016-02-22 13:49 ` Alan Cox
2016-02-22 20:46 ` Jesse Barnes
2016-02-23 16:19 ` Simon Guinot
2016-02-23 17:19 ` Jesse Barnes
2016-02-23 21:38 ` One Thousand Gnomes
2016-02-24 14:25 ` [PATCH] kernel/resource.c: ensure parent is not freed " Simon Guinot
2016-02-23 8:00 ` [PATCH] kernel/resource.c: fix muxed resource handling " Vincent Pelletier
2015-09-12 13:26 ` [1/4] gpio: gpio-f7188x: Use mutex for access serialisation Vincent Pelletier
2015-09-04 13:48 ` Vincent Donnefort
2015-09-05 7:43 ` Vincent Pelletier
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