watchdog: Simplify a little the IPI call

In order to remotely restart the watchdog hrtimer, update_timers()
allocates a csd on the stack and pass it to __smp_call_function_single().

There is no partcular need, however, for a specific csd here. Lets
simplify that a little by calling smp_call_function_single()
which can already take care of the csd allocation by itself.

Acked-by: Don Zickus <dzickus@redhat.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@fb.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

kernel/watchdog.c

@@ -505,7 +505,6 @@ static void restart_watchdog_hrtimer(void *info)
 
 static void update_timers(int cpu)
 {
-	struct call_single_data data = {.func = restart_watchdog_hrtimer};
 	/*
 	 * Make sure that perf event counter will adopt to a new
 	 * sampling period. Updating the sampling period directly would
@@ -515,7 +514,7 @@ static void update_timers(int cpu)
 	 * might be late already so we have to restart the timer as well.
 	 */
 	watchdog_nmi_disable(cpu);
-	__smp_call_function_single(cpu, &data, 1);
+	smp_call_function_single(cpu, restart_watchdog_hrtimer, NULL, 1);
 	watchdog_nmi_enable(cpu);
 }