clocksource: Initialize cs->wd_list

commit 5b9e886 upstream.

A number of places relies on list_empty(&cs->wd_list), however the
list_head does not get initialized. Do so upon registration, such that
thereafter it is possible to rely on list_empty() correctly reflecting
the list membership status.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Diego Viola <[email protected]>
Reviewed-by: Rafael J. Wysocki <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sudip Mukherjee <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Peter Zijlstra

kernel/time/clocksource.c

@@ -322,6 +322,8 @@ static void clocksource_enqueue_watchdog(struct clocksource *cs)
 {
 	unsigned long flags;
 
+	INIT_LIST_HEAD(&cs->wd_list);
+
 	spin_lock_irqsave(&watchdog_lock, flags);
 	if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) {
 		/* cs is a clocksource to be watched. */