linux-kernel - Re: [PATCH 1/8] fs/9p: Deletion of unnecessary checks before the function call "p9_client

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Date:	Sun, 28 Dec 2014 22:01:28 +0100 (CET)
From:	Julia Lawall <julia.lawall@...6.fr>
To:	SF Markus Elfring <elfring@...rs.sourceforge.net>
cc:	Eric Van Hensbergen <ericvh@...il.com>,
	Latchesar Ionkov <lucho@...kov.net>,
	Ron Minnich <rminnich@...dia.gov>,
	v9fs-developer@...ts.sourceforge.net,
	LKML <linux-kernel@...r.kernel.org>,
	kernel-janitors@...r.kernel.org,
	Julia Lawall <julia.lawall@...6.fr>
Subject: Re: [PATCH 1/8] fs/9p: Deletion of unnecessary checks before the
 function call "p9_client_clunk"

> diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
> index 9ee5343..a787d4c 100644
> --- a/fs/9p/vfs_inode.c
> +++ b/fs/9p/vfs_inode.c
> @@ -700,11 +700,9 @@ v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
>  	}
>  	return ofid;
>  error:
> -	if (ofid)
> -		p9_client_clunk(ofid);
> +	p9_client_clunk(ofid);
>  
> -	if (fid)
> -		p9_client_clunk(fid);
> +	p9_client_clunk(fid);
>  
>  	return ERR_PTR(err);
>  }

This code seems rather sloppy.  ofid could never be NULL at the point 
where it was tested.  There is a useless definition of ofid to NULL at the 
top of the function.  The error handling code could be rearranged with an 
extra error label so that p9_client_clunk is never called on fid when it 
it is not defined.  The the two assignments of fid to NULL could also be 
removed.  There is also a useless initialization of err to 0 at the 
beginning of the function.  And the first two calls to ERR_PTR are not 
needed, as the types of dfid and ofid are the same as the return type of 
the function.

> @@ -768,8 +766,7 @@ static int v9fs_vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode
>  		v9fs_invalidate_inode_attr(dir);
>  	}
>  
> -	if (fid)
> -		p9_client_clunk(fid);
> +	p9_client_clunk(fid);
>  
>  	return err;
>  }

This function is also unnecessarily complex.  The if above this one, that 
detects the error could just return PTR_ERR(fid);.  The rest of the 
function could call inc_nlink, v9fs_invalidate_inode_attr, and 
p9_client_clunk, and the returnvalue could be 0, removing the need for the 
err variable.

> @@ -916,8 +913,7 @@ out:
>  	return err;
>  
>  error:
> -	if (fid)
> -		p9_client_clunk(fid);
> +	p9_client_clunk(fid);
>  	goto out;
>  }

In the case where fid is set to NULL, it could just goto out directly, 
instead of calling p9_client_clunk, testing fid, coming back, and going to 
out anyway.

julia
  
> diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
> index 6054c16b..3611b0f 100644
> --- a/fs/9p/vfs_inode_dotl.c
> +++ b/fs/9p/vfs_inode_dotl.c
> @@ -363,11 +363,9 @@ out:
>  	return err;
>  
>  error:
> -	if (fid)
> -		p9_client_clunk(fid);
> +	p9_client_clunk(fid);
>  err_clunk_old_fid:
> -	if (ofid)
> -		p9_client_clunk(ofid);
> +	p9_client_clunk(ofid);
>  	goto out;
>  }
>  
> @@ -464,8 +462,7 @@ static int v9fs_vfs_mkdir_dotl(struct inode *dir,
>  	inc_nlink(dir);
>  	v9fs_invalidate_inode_attr(dir);
>  error:
> -	if (fid)
> -		p9_client_clunk(fid);
> +	p9_client_clunk(fid);
>  	v9fs_put_acl(dacl, pacl);
>  	return err;
>  }
> @@ -744,8 +741,7 @@ v9fs_vfs_symlink_dotl(struct inode *dir, struct dentry *dentry,
>  	}
>  
>  error:
> -	if (fid)
> -		p9_client_clunk(fid);
> +	p9_client_clunk(fid);
>  
>  	return err;
>  }
> @@ -896,8 +892,7 @@ v9fs_vfs_mknod_dotl(struct inode *dir, struct dentry *dentry, umode_t omode,
>  		d_instantiate(dentry, inode);
>  	}
>  error:
> -	if (fid)
> -		p9_client_clunk(fid);
> +	p9_client_clunk(fid);
>  	v9fs_put_acl(dacl, pacl);
>  	return err;
>  }
> diff --git a/fs/9p/xattr.c b/fs/9p/xattr.c
> index f95e01e..8e72269 100644
> --- a/fs/9p/xattr.c
> +++ b/fs/9p/xattr.c
> @@ -65,8 +65,7 @@ ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
>  	/* Total read xattr bytes */
>  	retval = offset;
>  error:
> -	if (attr_fid)
> -		p9_client_clunk(attr_fid);
> +	p9_client_clunk(attr_fid);
>  	return retval;
>  
>  }
> -- 
> 2.2.1
> 
> 
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