MIPS: SMTC: Fix lockup in smtc_distribute_timer

1. At the end of smtc_distribute_timer, nextstamp is valid and has already
   passed so we goto repeat.
2. Nothing updates nextstamp (only updated if the timeout is in the future
   And we just decided it is in the past)
3. At the end nextstamp still has the same value so it is still valid and
   in the past.
4. This repeats until read_c0_count has a value which causes nextstamp to
   be in the future.

Reported and initial patch and testing  by Mikael Starvik
<mikael.starvik@axis.com>.

Signed-off-by: Kevin D. Kissell <kevink@paralogos.com>
Cc: Mikael Starvik <mikael.starvik@axis.com>
Cc: linux-mips@linux-mips.org
Cc: Jesper Nilsson <Jesper.Nilsson@axis.com>
Patchwork: http://patchwork.linux-mips.org/patch/621/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/kernel/cevt-smtc.c b/arch/mips/kernel/cevt-smtc.c
index 98bd7de..b102e4f 100644 (file)
--- a/arch/mips/kernel/cevt-smtc.c
+++ b/arch/mips/kernel/cevt-smtc.c
@@ -173,11 +173,12 @@ void smtc_distribute_timer(int vpe)
        unsigned int mtflags;
        int cpu;
        struct clock_event_device *cd;
-       unsigned long nextstamp = 0L;
+       unsigned long nextstamp;
        unsigned long reference;
 
 
 repeat:
+       nextstamp = 0L;
        for_each_online_cpu(cpu) {
            /*
             * Find virtual CPUs within the current VPE who have