powerpc/spufs: Fix possible scheduling of a context to multiple SPEs

We currently have a race when scheduling a context to a SPE -
after we have found a runnable context in spusched_tick, the same
context may have been scheduled by spu_activate().

This may result in a panic if we try to unschedule a context that has
been freed in the meantime.

This change exits spu_schedule() if the context has already been
scheduled, so we don't end up scheduling it twice.

Signed-off-by: Andre Detsch <adetsch@br.ibm.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 897c740..67595bc 100644 (file)
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -728,7 +728,8 @@ static void spu_schedule(struct spu *spu, struct spu_context *ctx)
        /* not a candidate for interruptible because it's called either
           from the scheduler thread or from spu_deactivate */
        mutex_lock(&ctx->state_mutex);
-       __spu_schedule(spu, ctx);
+       if (ctx->state == SPU_STATE_SAVED)
+               __spu_schedule(spu, ctx);
        spu_release(ctx);
 }