[POWERPC] spufs: state_mutex cleanup

Various cleanups in code surrounding the state semaphore:

 - inline spu_acquire/spu_release
 - cleanup spu_acquire_* and add kerneldoc comments to these functions
 - remove spu_release_exclusive and replace it with spu_release

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

3 files changed, 64 insertions, 53 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/context.c b/arch/powerpc/platforms/cell/spufs/context.c
index c9aab9b1cd8..f2630dc0db8 100644
--- a/arch/powerpc/platforms/cell/spufs/context.c
+++ b/arch/powerpc/platforms/cell/spufs/context.c
@@ -96,16 +96,6 @@ void spu_forget(struct spu_context *ctx)
         spu_release(ctx);
 }
 
-void spu_acquire(struct spu_context *ctx)
-{
-        mutex_lock(&ctx->state_mutex);
-}
-
-void spu_release(struct spu_context *ctx)
-{
-        mutex_unlock(&ctx->state_mutex);
-}
-
 void spu_unmap_mappings(struct spu_context *ctx)
 {
         if (ctx->local_store)
@@ -124,66 +114,85 @@ void spu_unmap_mappings(struct spu_context *ctx)
                 unmap_mapping_range(ctx->psmap, 0, 0x20000, 1);
 }
 
+/**
+ * spu_acquire_exclusive - lock spu contex and protect against userspace access
+ * @ctx:        spu contex to lock
+ *
+ * Note:
+ *      Returns 0 and with the context locked on success
+ *      Returns negative error and with the context _unlocked_ on failure.
+ */
 int spu_acquire_exclusive(struct spu_context *ctx)
 {
-        int ret = 0;
+        int ret = -EINVAL;
 
-        mutex_lock(&ctx->state_mutex);
-        /* ctx is about to be freed, can't acquire any more */
-        if (!ctx->owner) {
-                ret = -EINVAL;
-                goto out;
-        }
+        spu_acquire(ctx);
+        /*
+         * Context is about to be freed, so we can't acquire it anymore.
+         */
+        if (!ctx->owner)
+                goto out_unlock;
 
         if (ctx->state == SPU_STATE_SAVED) {
                 ret = spu_activate(ctx, 0);
                 if (ret)
-                        goto out;
+                        goto out_unlock;
         } else {
-                /* We need to exclude userspace access to the context. */
+                /*
+                 * We need to exclude userspace access to the context.
+                 *
+                 * To protect against memory access we invalidate all ptes
+                 * and make sure the pagefault handlers block on the mutex.
+                 */
                 spu_unmap_mappings(ctx);
         }
 
-out:
-        if (ret)
-                mutex_unlock(&ctx->state_mutex);
+        return 0;
+
+ out_unlock:
+        spu_release(ctx);
         return ret;
 }
 
+/**
+ * spu_acquire_runnable - lock spu contex and make sure it is in runnable state
+ * @ctx:        spu contex to lock
+ *
+ * Note:
+ *      Returns 0 and with the context locked on success
+ *      Returns negative error and with the context _unlocked_ on failure.
+ */
 int spu_acquire_runnable(struct spu_context *ctx)
 {
-        int ret = 0;
-
-        mutex_lock(&ctx->state_mutex);
-        if (ctx->state == SPU_STATE_RUNNABLE) {
-                ctx->spu->prio = current->prio;
-                return 0;
-        }
-
-        /* ctx is about to be freed, can't acquire any more */
-        if (!ctx->owner) {
-                ret = -EINVAL;
-                goto out;
-        }
+        int ret = -EINVAL;
 
+        spu_acquire(ctx);
         if (ctx->state == SPU_STATE_SAVED) {
+                /*
+                 * Context is about to be freed, so we can't acquire it anymore.
+                 */
+                if (!ctx->owner)
+                        goto out_unlock;
                 ret = spu_activate(ctx, 0);
                 if (ret)
-                        goto out;
-        }
+                        goto out_unlock;
+        } else
+                ctx->spu->prio = current->prio;
 
-        /* On success, we return holding the lock */
-        return ret;
-out:
-        /* Release here, to simplify calling code. */
-        mutex_unlock(&ctx->state_mutex);
+        return 0;
 
+ out_unlock:
+        spu_release(ctx);
         return ret;
 }
 
+/**
+ * spu_acquire_saved - lock spu contex and make sure it is in saved state
+ * @ctx:        spu contex to lock
+ */
 void spu_acquire_saved(struct spu_context *ctx)
 {
-        mutex_lock(&ctx->state_mutex);
-        if (ctx->state == SPU_STATE_RUNNABLE)
+        spu_acquire(ctx);
+        if (ctx->state != SPU_STATE_SAVED)
                 spu_deactivate(ctx);
 }
diff --git a/arch/powerpc/platforms/cell/spufs/run.c b/arch/powerpc/platforms/cell/spufs/run.c
index 51b78da2f0d..e1647311044 100644
--- a/arch/powerpc/platforms/cell/spufs/run.c
+++ b/arch/powerpc/platforms/cell/spufs/run.c
@@ -133,7 +133,7 @@ out_drop_priv:
         spu_mfc_sr1_set(ctx->spu, sr1);
 
 out_unlock:
-        spu_release_exclusive(ctx);
+        spu_release(ctx);
 out:
         return ret;
 }
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index de2401afb22..fa07ec2e2c1 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -158,6 +158,16 @@ void spu_gang_remove_ctx(struct spu_gang *gang, struct spu_context *ctx);
 void spu_gang_add_ctx(struct spu_gang *gang, struct spu_context *ctx);
 
 /* context management */
+static inline void spu_acquire(struct spu_context *ctx)
+{
+        mutex_lock(&ctx->state_mutex);
+}
+
+static inline void spu_release(struct spu_context *ctx)
+{
+        mutex_unlock(&ctx->state_mutex);
+}
+
 struct spu_context * alloc_spu_context(struct spu_gang *gang);
 void destroy_spu_context(struct kref *kref);
 struct spu_context * get_spu_context(struct spu_context *ctx);
@@ -165,17 +175,9 @@ int put_spu_context(struct spu_context *ctx);
 void spu_unmap_mappings(struct spu_context *ctx);
 
 void spu_forget(struct spu_context *ctx);
-void spu_acquire(struct spu_context *ctx);
-void spu_release(struct spu_context *ctx);
 int spu_acquire_runnable(struct spu_context *ctx);
 void spu_acquire_saved(struct spu_context *ctx);
 int spu_acquire_exclusive(struct spu_context *ctx);
-
-static inline void spu_release_exclusive(struct spu_context *ctx)
-{
-        mutex_unlock(&ctx->state_mutex);
-}
-
 int spu_activate(struct spu_context *ctx, u64 flags);
 void spu_deactivate(struct spu_context *ctx);
 void spu_yield(struct spu_context *ctx);