On Thu, Aug 22, 2013 at 5:41 AM, Axel Lin <axel....@ingics.com> wrote: > 2013/8/22 Linus Walleij <linus.wall...@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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
