[POWERPC] spusched: Update scheduling paramters on every spu_run

Update scheduling information on every spu_run to allow for setting
threads to realtime priority just before running them.  This requires
some slightly ugly code in spufs_run_spu because we can just update
the information unlocked if the spu is not runnable, but we need to
acquire the active_mutex when it is runnable to protect against
find_victim.  This locking scheme requires opencoding
spu_acquire_runnable in spufs_run_spu which actually is a nice cleanup
all by itself.

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>

4 files changed, 45 insertions, 14 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/context.c b/arch/powerpc/platforms/cell/spufs/context.c
index c5ec7cfc24b5..c778d9178e0f 100644
--- a/arch/powerpc/platforms/cell/spufs/context.c
+++ b/arch/powerpc/platforms/cell/spufs/context.c
@@ -54,17 +54,6 @@ struct spu_context *alloc_spu_context(struct spu_gang *gang)
         if (gang)
                 spu_gang_add_ctx(gang, ctx);
 
-        /*
-         * We do our own priority calculations, so we normally want
-         * ->static_prio to start with. Unfortunately thies field
-         * contains junk for threads with a realtime scheduling
-         * policy so we have to look at ->prio in this case.
-         */
-        if (rt_prio(current->prio))
-                ctx->prio = current->prio;
-        else
-                ctx->prio = current->static_prio;
-        ctx->policy = current->policy;
         spu_set_timeslice(ctx);
         goto out;
 out_free:
diff --git a/arch/powerpc/platforms/cell/spufs/run.c b/arch/powerpc/platforms/cell/spufs/run.c
index 89b02b6bfc55..4e0db6ae0d5e 100644
--- a/arch/powerpc/platforms/cell/spufs/run.c
+++ b/arch/powerpc/platforms/cell/spufs/run.c
@@ -301,9 +301,22 @@ long spufs_run_spu(struct file *file, struct spu_context *ctx,
         ctx->ops->master_start(ctx);
         ctx->event_return = 0;
 
-        ret = spu_acquire_runnable(ctx, 0);
-        if (ret)
-                return ret;
+        spu_acquire(ctx);
+        if (ctx->state == SPU_STATE_SAVED) {
+                __spu_update_sched_info(ctx);
+
+                ret = spu_activate(ctx, 0);
+                if (ret) {
+                        spu_release(ctx);
+                        goto out;
+                }
+        } else {
+                /*
+                 * We have to update the scheduling priority under active_mutex
+                 * to protect against find_victim().
+                 */
+                spu_update_sched_info(ctx);
+        }
 
         ret = spu_run_init(ctx, npc);
         if (ret) {
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 002b40af4a77..3707c7fdbdee 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -96,6 +96,33 @@ void spu_set_timeslice(struct spu_context *ctx)
                 ctx->time_slice = SCALE_PRIO(DEF_SPU_TIMESLICE, ctx->prio);
 }
 
+/*
+ * Update scheduling information from the owning thread.
+ */
+void __spu_update_sched_info(struct spu_context *ctx)
+{
+        /*
+         * We do our own priority calculations, so we normally want
+         * ->static_prio to start with. Unfortunately thies field
+         * contains junk for threads with a realtime scheduling
+         * policy so we have to look at ->prio in this case.
+         */
+        if (rt_prio(current->prio))
+                ctx->prio = current->prio;
+        else
+                ctx->prio = current->static_prio;
+        ctx->policy = current->policy;
+}
+
+void spu_update_sched_info(struct spu_context *ctx)
+{
+        int node = ctx->spu->node;
+
+        mutex_lock(&spu_prio->active_mutex[node]);
+        __spu_update_sched_info(ctx);
+        mutex_unlock(&spu_prio->active_mutex[node]);
+}
+
 static inline int node_allowed(int node)
 {
         cpumask_t mask;
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index fddc59c204b5..ff77f904fa31 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -195,6 +195,8 @@ int spu_activate(struct spu_context *ctx, unsigned long flags);
 void spu_deactivate(struct spu_context *ctx);
 void spu_yield(struct spu_context *ctx);
 void spu_set_timeslice(struct spu_context *ctx);
+void spu_update_sched_info(struct spu_context *ctx);
+void __spu_update_sched_info(struct spu_context *ctx);
 int __init spu_sched_init(void);
 void __exit spu_sched_exit(void);