timers: Fix slack calculation for expired timers

commit 3bbb9ec946 (timers: Introduce the concept of timer slack for
legacy timers) does not take the case into account when the timer is
already expired. This broke wireless drivers.

The solution is not to apply slack to already expired timers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@linux.intel.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/kernel/timer.c b/kernel/timer.c
index 9199f3c52215..be394af5bc22 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -750,13 +750,14 @@ unsigned long apply_slack(struct timer_list *timer, unsigned long expires)
         unsigned long expires_limit, mask;
         int bit;
 
-        expires_limit = expires + timer->slack;
+        expires_limit = expires;
 
-        if (timer->slack < 0) /* auto slack: use 0.4% */
+        if (timer->slack > -1)
+                expires_limit = expires + timer->slack;
+        else if (time_after(expires, jiffies)) /* auto slack: use 0.4% */
                 expires_limit = expires + (expires - jiffies)/256;
 
         mask = expires ^ expires_limit;
-
         if (mask == 0)
                 return expires;