Subject: spufs: block in spu_acquire_runnable

From: Arnd Bergmann <arnd.bergmann@de.ibm.com>
This patch disables the logic that under the covers faults
in spu contexts from the page fault handler.

For the upstream version, we want something similar, but this
is a relatively straightforward patch to make the review easier.

Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>

Index: linux-2.6/arch/powerpc/platforms/cell/spufs/context.c
===================================================================
--- linux-2.6.orig/arch/powerpc/platforms/cell/spufs/context.c
+++ linux-2.6/arch/powerpc/platforms/cell/spufs/context.c
@@ -52,6 +52,7 @@ struct spu_context *alloc_spu_context(st
 	init_waitqueue_head(&ctx->wbox_wq);
 	init_waitqueue_head(&ctx->stop_wq);
 	init_waitqueue_head(&ctx->mfc_wq);
+	init_waitqueue_head(&ctx->run_wq);
 	ctx->state = SPU_STATE_SAVED;
 	ctx->ops = &spu_backing_ops;
 	ctx->owner = get_task_mm(current);
Index: linux-2.6/arch/powerpc/platforms/cell/spufs/file.c
===================================================================
--- linux-2.6.orig/arch/powerpc/platforms/cell/spufs/file.c
+++ linux-2.6/arch/powerpc/platforms/cell/spufs/file.c
@@ -245,7 +245,7 @@ static unsigned long spufs_ps_nopfn(stru
 	/* error here usually means a signal.. we might want to test
 	 * the error code more precisely though
 	 */
-	ret = spu_acquire_runnable(ctx, 0);
+	ret = spu_acquire_runnable(ctx, 1);
 	if (ret)
 		return NOPFN_REFAULT;
 
@@ -1500,7 +1500,7 @@ static ssize_t spufs_mfc_write(struct fi
 	if (ret)
 		goto out;
 
-	ret = spu_acquire_runnable(ctx, 0);
+	ret = spu_acquire_runnable(ctx, 1);
 	if (ret)
 		goto out;
 
Index: linux-2.6/arch/powerpc/platforms/cell/spufs/sched.c
===================================================================
--- linux-2.6.orig/arch/powerpc/platforms/cell/spufs/sched.c
+++ linux-2.6/arch/powerpc/platforms/cell/spufs/sched.c
@@ -630,10 +630,12 @@ static struct spu *find_victim(struct sp
 	return NULL;
 }
 
+
 /**
  * spu_activate - find a free spu for a context and execute it
  * @ctx:	spu context to schedule
- * @flags:	flags (currently ignored)
+ * @flags:	if nonzero, wait for context to become runnable,
+ *		instead of activating it from here.
  *
  * Tries to find a free spu to run @ctx.  If no free spu is available
  * add the context to the runqueue so it gets woken up once an spu
@@ -641,6 +643,10 @@ static struct spu *find_victim(struct sp
  */
 int spu_activate(struct spu_context *ctx, unsigned long flags)
 {
+	if (flags)
+		return spufs_wait(ctx->run_wq,
+			ctx->state == SPU_STATE_RUNNABLE);
+
 	do {
 		struct spu *spu;
 
@@ -667,6 +673,7 @@ int spu_activate(struct spu_context *ctx
 			spu_bind_context(spu, ctx);
 			cbe_spu_info[node].nr_active++;
 			mutex_unlock(&cbe_spu_info[node].list_mutex);
+			wake_up_all(&ctx->run_wq);
 			return 0;
 		}
 
Index: linux-2.6/arch/powerpc/platforms/cell/spufs/spufs.h
===================================================================
--- linux-2.6.orig/arch/powerpc/platforms/cell/spufs/spufs.h
+++ linux-2.6/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -71,6 +71,7 @@ struct spu_context {
 	wait_queue_head_t wbox_wq;
 	wait_queue_head_t stop_wq;
 	wait_queue_head_t mfc_wq;
+	wait_queue_head_t run_wq;
 	struct fasync_struct *ibox_fasync;
 	struct fasync_struct *wbox_fasync;
 	struct fasync_struct *mfc_fasync;