powerpc: Max next_tb to prevent from replaying timer interrupt

With lazy interrupt, we always call __check_irq_replaysome with
decrementers_next_tb to check if we need to replay timer interrupt.
So in hotplug case we also need to set decrementers_next_tb as MAX
to make sure __check_irq_replay don't replay timer interrupt
when return as we expect, otherwise we'll trap here infinitely.

Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 6f6b1cc..127361e 100644 (file)
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -494,10 +494,15 @@ void timer_interrupt(struct pt_regs * regs)
        set_dec(DECREMENTER_MAX);
 
        /* Some implementations of hotplug will get timer interrupts while
-        * offline, just ignore these
+        * offline, just ignore these and we also need to set
+        * decrementers_next_tb as MAX to make sure __check_irq_replay
+        * don't replay timer interrupt when return, otherwise we'll trap
+        * here infinitely :(
         */
-       if (!cpu_online(smp_processor_id()))
+       if (!cpu_online(smp_processor_id())) {
+               *next_tb = ~(u64)0;
                return;
+       }
 
        /* Conditionally hard-enable interrupts now that the DEC has been
         * bumped to its maximum value