[POWERPC] spusched: Catch nosched contexts in spu_deactivate

spu_deactivate should never be called for nosched contets.  Put in
a check so we can print a stacktrace and exit early in case it
happes erroneously.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/cell/spufs/sched.c

@@ -491,6 +491,15 @@ static int __spu_deactivate(struct spu_context *ctx, int force, int max_prio)
  */
 void spu_deactivate(struct spu_context *ctx)
 {
+	/*
+	 * We must never reach this for a nosched context,
+	 * but handle the case gracefull instead of panicing.
+	 */
+	if (ctx->flags & SPU_CREATE_NOSCHED) {
+		WARN_ON(1);
+		return;
+	}
+
 	__spu_deactivate(ctx, 1, MAX_PRIO);
 }