[RFC PATCH 1/5] watchdog: Add API to trigger reboots

On Mon, May 05, 2014 at 01:36:06PM -0500, Felipe Balbi wrote:

On Thu, May 01, 2014 at 08:41:29AM -0700, Guenter Roeck wrote:

quoted

Some hardware implements reboot through its watchdog hardware,
for example by triggering a watchdog timeout. Platform specific
code starts to spread into watchdog drivers, typically by setting
pointers to a callback functions which is then called from the
platform reset handler.

To simplify code and provide a unified API to trigger reboots by
watchdog drivers, provide a single API to trigger such reboots
through the watchdog subsystem.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/watchdog/watchdog_core.c |   17 +++++++++++++++++
 include/linux/watchdog.h         |   11 +++++++++++
 2 files changed, 28 insertions(+)

diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index cec9b55..4ec6e2f 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c

@@ -43,6 +43,17 @@
 static DEFINE_IDA(watchdog_ida);
 static struct class *watchdog_class;
 
+static struct watchdog_device *wdd_reboot_dev;
+
+void watchdog_do_reboot(enum reboot_mode mode, const char *cmd)
+{
+	if (wdd_reboot_dev) {
+		if (wdd_reboot_dev->ops->reboot)

you can decrease one level of indentation:

	if (wdd_reboot_dev && wdd_reboot_dev->ops->reboot)

also, shouldn't you test if 'ops' is valid too ? In that case:

	if (wdd_reboot_dev && wdd_reboot_dev->ops &&
		wdd_reboot_dev->ops->reboot)

Hmmm ... makes me think.

If ops->reboot is not set, wdd_reboot_dev should be NULL
to start with, since it is only initialized if ops->reboot
is not NULL.

It is not common in the Linux kernel to re-check pointers
if the condition can not occur, so I don't think it should
be done here.

In other words, I should probably remove the ops check as well.

Guenter