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authorRasmus Villemoes <linux@rasmusvillemoes.dk>2019-11-05 21:51:18 +0100
committerWim Van Sebroeck <wim@linux-watchdog.org>2019-11-18 19:53:43 +0100
commitbc44fa734cef28e7ddb26bbf9e75e7f7449c9db2 (patch)
treee7c5aaf051523dfd27b25f47c377b6cc8093ff72 /drivers/watchdog
parenta19f89335f4bda3d77d991c96583e3e51856acbb (diff)
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 <linux@rasmusvillemoes.dk> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/20191105205118.11359-1-linux@rasmusvillemoes.dk Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Diffstat (limited to 'drivers/watchdog')
-rw-r--r--drivers/watchdog/watchdog_dev.c21
1 files changed, 20 insertions, 1 deletions
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)