Messages in this thread | | | Date | Wed, 28 Aug 2013 13:13:00 +0200 | Subject | Re: [PATCH 2/2] pinctrl: core: Add proper mutex lock in pinctrl_request_gpio | From | Linus Walleij <> |
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On Thu, Aug 22, 2013 at 5:41 AM, Axel Lin <axel.lin@ingics.com> wrote: > 2013/8/22 Linus Walleij <linus.walleij@linaro.org>:
>>> + mutex_lock(&pctldev->mutex); >>> + >>> /* Convert to the pin controllers number space */ >>> pin = gpio_to_pin(range, gpio); >>> >>> ret = pinmux_request_gpio(pctldev, range, pin, gpio); >>> >>> + mutex_unlock(&pctldev->mutex); >>> + >>> return ret; >> >> What is this protecting against? >> >> I'm not sure I follow this so better ask. > > I think this fixes the race between pin_free() and pin_request() calls. > (Well, I don't have a h/w to test at this moment.) > It protects accessing the members of pctldev->desc. > (e.g. update desc->mux_usecount, desc->gpio_owner, desc->mux_owner, etc) > Current code grabs pctldev->mutex before calling pinmux_free_gpio(), > but did not grab the mutex while calling pinmux_request_gpio().
OK you won me over, patch applied!
I also edited in some of the above text into the commit.
Yours, Linus Walleij
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