[POWERPC] spufs: streamline locking for isolated spu setup

For quite a while now spu state is protected by a simple mutex instead
of the old rw_semaphore, and this means we can simplify the locking
around spu_setup_isolated a lot.

Instead of doing an spu_release before entering spu_setup_isolated and
then calling the complicated spu_acquire_exclusive we can now simply
enter the function locked an in guaranteed runnable state, so that the
only bit of spu_acquire_exclusive that's left is the call to
spu_unmap_mappings.

Similarly there's no more need to unlock and reacquire the state_mutex
when spu_setup_isolated is done, but we can always return with the
lock held and only drop it in spu_run_init in the failure case.

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

3 files changed, 16 insertions, 55 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/context.c b/arch/powerpc/platforms/cell/spufs/context.c
index 065147fb1cc2..ce17a2847184 100644
--- a/arch/powerpc/platforms/cell/spufs/context.c
+++ b/arch/powerpc/platforms/cell/spufs/context.c
@@ -122,46 +122,6 @@ void spu_unmap_mappings(struct spu_context *ctx)
 }
 
 /**
- * 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 = -EINVAL;
-
-        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_unlock;
-        } else {
-                /*
-                 * 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);
-        }
-
-        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
  *
diff --git a/arch/powerpc/platforms/cell/spufs/run.c b/arch/powerpc/platforms/cell/spufs/run.c
index f95a611ca362..7df5202c9a90 100644
--- a/arch/powerpc/platforms/cell/spufs/run.c
+++ b/arch/powerpc/platforms/cell/spufs/run.c
@@ -63,13 +63,18 @@ static int spu_setup_isolated(struct spu_context *ctx)
         const u32 status_loading = SPU_STATUS_RUNNING
                 | SPU_STATUS_ISOLATED_STATE | SPU_STATUS_ISOLATED_LOAD_STATUS;
 
+        ret = -ENODEV;
         if (!isolated_loader)
-                return -ENODEV;
-
-        ret = spu_acquire_exclusive(ctx);
-        if (ret)
                 goto out;
 
+        /*
+         * 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);
+
         mfc_cntl = &ctx->spu->priv2->mfc_control_RW;
 
         /* purge the MFC DMA queue to ensure no spurious accesses before we
@@ -82,7 +87,7 @@ static int spu_setup_isolated(struct spu_context *ctx)
                         printk(KERN_ERR "%s: timeout flushing MFC DMA queue\n",
                                         __FUNCTION__);
                         ret = -EIO;
-                        goto out_unlock;
+                        goto out;
                 }
                 cond_resched();
         }
@@ -119,12 +124,15 @@ static int spu_setup_isolated(struct spu_context *ctx)
                 pr_debug("%s: isolated LOAD failed\n", __FUNCTION__);
                 ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
                 ret = -EACCES;
+                goto out_drop_priv;
+        }
 
-        } else if (!(status & SPU_STATUS_ISOLATED_STATE)) {
+        if (!(status & SPU_STATUS_ISOLATED_STATE)) {
                 /* This isn't allowed by the CBEA, but check anyway */
                 pr_debug("%s: SPU fell out of isolated mode?\n", __FUNCTION__);
                 ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_STOP);
                 ret = -EINVAL;
+                goto out_drop_priv;
         }
 
 out_drop_priv:
@@ -132,8 +140,6 @@ out_drop_priv:
         sr1 |= MFC_STATE1_PROBLEM_STATE_MASK;
         spu_mfc_sr1_set(ctx->spu, sr1);
 
-out_unlock:
-        spu_release(ctx);
 out:
         return ret;
 }
@@ -149,13 +155,9 @@ static inline int spu_run_init(struct spu_context *ctx, u32 * npc)
 
         if (ctx->flags & SPU_CREATE_ISOLATE) {
                 if (!(ctx->ops->status_read(ctx) & SPU_STATUS_ISOLATED_STATE)) {
-                        /* Need to release ctx, because spu_setup_isolated will
-                         * acquire it exclusively.
-                         */
-                        spu_release(ctx);
                         ret = spu_setup_isolated(ctx);
-                        if (!ret)
-                                ret = spu_acquire_runnable(ctx, 0);
+                        if (ret)
+                                spu_release(ctx);
                 }
 
                 /* if userspace has set the runcntrl register (eg, to issue an
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index 0fb366d9d257..cae2ad435b0a 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -192,7 +192,6 @@ void spu_unmap_mappings(struct spu_context *ctx);
 void spu_forget(struct spu_context *ctx);
 int spu_acquire_runnable(struct spu_context *ctx, unsigned long flags);
 void spu_acquire_saved(struct spu_context *ctx);
-int spu_acquire_exclusive(struct spu_context *ctx);
 
 int spu_activate(struct spu_context *ctx, unsigned long flags);
 void spu_deactivate(struct spu_context *ctx);