posix-timers: Add cond_resched() to posix_timer_add() search loop

With a large number of POSIX timers the search for a valid ID might cause a
soft lockup on PREEMPT_NONE/VOLUNTARY kernels.

Add cond_resched() to the loop to prevent that.

[ tglx: Split out from Eric's series ]

Signed-off-by: Eric Dumazet <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Frederic Weisbecker <[email protected]>
Link: https://lore.kernel.org/all/[email protected]
Link: https://lore.kernel.org/all/[email protected]

Author: edumazet

kernel/time/posix-timers.c

@@ -144,6 +144,7 @@ static int posix_timer_add(struct k_itimer *timer)
 			return id;
 		}
 		spin_unlock(&hash_lock);
+		cond_resched();
 	}
 	/* POSIX return code when no timer ID could be allocated */
 	return -EAGAIN;