rtc: check if __rtc_read_time was successful

Clang static analysis reports this issue
interface.c:810:8: warning: Passed-by-value struct
  argument contains uninitialized data
  now = rtc_tm_to_ktime(tm);
      ^~~~~~~~~~~~~~~~~~~

tm is set by a successful call to __rtc_read_time()
but its return status is not checked.  Check if
it was successful before setting the enabled flag.
Move the decl of err to function scope.

Fixes: 2b2f5ff00f63 ("rtc: interface: ignore expired timers when enqueuing new timers")
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220326194236.2916310-1-trix@redhat.com

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index d8e835798153730ff76531aee9c9ac9e90eaeb4c..9edd662c69ace4da09ef528e6b8216114987be9e 100644 (file)
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -804,9 +804,13 @@ static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
        struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
        struct rtc_time tm;
        ktime_t now;
+       int err;
+
+       err = __rtc_read_time(rtc, &tm);
+       if (err)
+               return err;
 
        timer->enabled = 1;
-       __rtc_read_time(rtc, &tm);
        now = rtc_tm_to_ktime(tm);
 
        /* Skip over expired timers */
@@ -820,7 +824,6 @@ static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
        trace_rtc_timer_enqueue(timer);
        if (!next || ktime_before(timer->node.expires, next->expires)) {
                struct rtc_wkalrm alarm;
-               int err;
 
                alarm.time = rtc_ktime_to_tm(timer->node.expires);
                alarm.enabled = 1;