[PATCH] power: reset: msm: Process register_restart_handler() error

[Nikita Kiryushin]

If registering restart handler fails for msm-restart result is not checked.
It may be irrelevant now (as stated in comment to register_restart_handler,
the function currently always returns zero), but if the behavior changes
in the future, an error at registration of handler will be silently skipped.

Add return error code and print error message too debug log in case of
non-zero result of register_restart_handler.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 18a702e0de98 ("power: reset: use restart_notifier mechanism for 
msm-poweroff")

Signed-off-by: Nikita Kiryushin <kiryushin@xxxxxxxx>
---
 drivers/power/reset/msm-poweroff.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/power/reset/msm-poweroff.c 
b/drivers/power/reset/msm-poweroff.c
index b9a401bd280b..5877a1ba2778 100644
--- a/drivers/power/reset/msm-poweroff.c
+++ b/drivers/power/reset/msm-poweroff.c
@@ -35,11 +35,16 @@ static void do_msm_poweroff(void)
  static int msm_restart_probe(struct platform_device *pdev)
 {
+	int ret = -EINVAL;
 	msm_ps_hold = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(msm_ps_hold))
 		return PTR_ERR(msm_ps_hold);
 -	register_restart_handler(&restart_nb);
+	ret = register_restart_handler(&restart_nb);
+	if (ret) {
+		dev_err(&pdev->dev, "unable to register restart handler, %d\n", ret);
+		return ret;
+	}
  	pm_power_off = do_msm_poweroff;
 -- 2.34.1