[POWERPC] spufs: fix deadlock in spu_create error path

spufs_rmdir tries to acquire the spufs root
i_mutex, which is already held by spufs_create_thread.

This was tracked as Bug #H9512.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 15 insertions, 11 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/inode.c b/arch/powerpc/platforms/cell/spufs/inode.c
index d9554199afa7..fed511a2b17f 100644
--- a/arch/powerpc/platforms/cell/spufs/inode.c
+++ b/arch/powerpc/platforms/cell/spufs/inode.c
@@ -157,20 +157,12 @@ static void spufs_prune_dir(struct dentry *dir)
         mutex_unlock(&dir->d_inode->i_mutex);
 }
 
+/* Caller must hold root->i_mutex */
 static int spufs_rmdir(struct inode *root, struct dentry *dir_dentry)
 {
-        struct spu_context *ctx;
-
         /* remove all entries */
-        mutex_lock(&root->i_mutex);
         spufs_prune_dir(dir_dentry);
-        mutex_unlock(&root->i_mutex);
 
-        /* We have to give up the mm_struct */
-        ctx = SPUFS_I(dir_dentry->d_inode)->i_ctx;
-        spu_forget(ctx);
-
-        /* XXX Do we need to hold i_mutex here ? */
         return simple_rmdir(root, dir_dentry);
 }
 
@@ -199,16 +191,23 @@ out:
 
 static int spufs_dir_close(struct inode *inode, struct file *file)
 {
+        struct spu_context *ctx;
         struct inode *dir;
         struct dentry *dentry;
         int ret;
 
         dentry = file->f_dentry;
         dir = dentry->d_parent->d_inode;
+        ctx = SPUFS_I(dentry->d_inode)->i_ctx;
 
+        mutex_lock(&dir->i_mutex);
         ret = spufs_rmdir(dir, dentry);
+        mutex_unlock(&dir->i_mutex);
         WARN_ON(ret);
 
+        /* We have to give up the mm_struct */
+        spu_forget(ctx);
+
         return dcache_dir_close(inode, file);
 }
 
@@ -324,8 +323,13 @@ long spufs_create_thread(struct nameidata *nd,
          * in error path of *_open().
          */
         ret = spufs_context_open(dget(dentry), mntget(nd->mnt));
-        if (ret < 0)
-                spufs_rmdir(nd->dentry->d_inode, dentry);
+        if (ret < 0) {
+                WARN_ON(spufs_rmdir(nd->dentry->d_inode, dentry));
+                mutex_unlock(&nd->dentry->d_inode->i_mutex);
+                spu_forget(SPUFS_I(dentry->d_inode)->i_ctx);
+                dput(dentry);
+                goto out;
+        }
 
 out_dput:
         dput(dentry);