From bc44fa734cef28e7ddb26bbf9e75e7f7449c9db2 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Tue, 5 Nov 2019 21:51:18 +0100 Subject: watchdog: make nowayout sysfs file writable It can be useful to delay setting the nowayout feature for a watchdog device. Moreover, not every driver (notably gpio_wdt) implements a nowayout module parameter/otherwise respects CONFIG_WATCHDOG_NOWAYOUT, and modifying those drivers carries a risk of causing a regression for someone who has two watchdog devices, sets CONFIG_WATCHDOG_NOWAYOUT and somehow relies on the gpio_wdt driver being ignorant of that (i.e., allowing one to gracefully close a gpio_wdt but not the other watchdog in the system). So instead, simply make the nowayout sysfs file writable. Obviously, setting nowayout is a one-way street. Signed-off-by: Rasmus Villemoes Reviewed-by: Guenter Roeck Link: https://lore.kernel.org/r/20191105205118.11359-1-linux@rasmusvillemoes.dk Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck --- drivers/watchdog/watchdog_dev.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) (limited to 'drivers/watchdog') diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index 62483a99105c..4feecd14e9ab 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -452,7 +452,26 @@ static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr, return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status)); } -static DEVICE_ATTR_RO(nowayout); + +static ssize_t nowayout_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t len) +{ + struct watchdog_device *wdd = dev_get_drvdata(dev); + unsigned int value; + int ret; + + ret = kstrtouint(buf, 0, &value); + if (ret) + return ret; + if (value > 1) + return -EINVAL; + /* nowayout cannot be disabled once set */ + if (test_bit(WDOG_NO_WAY_OUT, &wdd->status) && !value) + return -EPERM; + watchdog_set_nowayout(wdd, value); + return len; +} +static DEVICE_ATTR_RW(nowayout); static ssize_t status_show(struct device *dev, struct device_attribute *attr, char *buf) -- cgit v1.2.3