[PATCH] fs: uselib - Set error on do_filp_open failure only

[PATCH] fs: uselib - Set error on do_filp_open failure only

[Sasikanth V]

At present "error" is set irrespective of do_filp_open failed or not.
Setting error to PTR_ERR(file) on do_filp_open failure only.

Signed-off-by: Sasikanth V <sasikanth.v19@gmail.com>
---
 fs/exec.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index b1fd202..cb43367 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -129,9 +129,10 @@ SYSCALL_DEFINE1(uselib, const char __user *, library)
 
 	file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW);
 	putname(tmp);
-	error = PTR_ERR(file);
-	if (IS_ERR(file))
+	if (IS_ERR(file)) {
+		error = PTR_ERR(file);
 		goto out;
+	}
 
 	error = -EINVAL;
 	if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
-- 
1.7.3.4

Re: [PATCH] fs: uselib - Set error on do_filp_open failure only

[Jesper Juhl]

On Sun, 22 Apr 2012, Sasikanth V wrote:

> At present "error" is set irrespective of do_filp_open failed or not.
> Setting error to PTR_ERR(file) on do_filp_open failure only.
> 
> Signed-off-by: Sasikanth V <sasikanth.v19@gmail.com>
> ---
>  fs/exec.c |    5 +++--
>  1 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/exec.c b/fs/exec.c
> index b1fd202..cb43367 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -129,9 +129,10 @@ SYSCALL_DEFINE1(uselib, const char __user *, library)
>  
>  	file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW);
>  	putname(tmp);
> -	error = PTR_ERR(file);
> -	if (IS_ERR(file))
> +	if (IS_ERR(file)) {
> +		error = PTR_ERR(file);
>  		goto out;
> +	}
>       error = -EINVAL;
>       if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
>


Ok, maybe I'm just stupid, but I really don't see the point of this patch.

With the original code, if "IS_ERR(file)" is true we'll "goto out" with 
'error' set to 'PTR_ERR(file)' and if it is false we'll set 'error = 
-EINVAL' and continue on...

With your new version we will, as I read the code, "goto out" with "error 
= PTR_ERR(file)" if "IS_ERR(file)" is true and if it is false we'll set 
'error = -EINVAL' and continue.

As I see it, there's no difference, except that your new version adds one 
extra line to the source file.

Am I missing something (as in "being completely braindead") or??


-- 
Jesper Juhl <jj@chaosbits.net>       http://www.chaosbits.net/
Don't top-post http://www.catb.org/jargon/html/T/top-post.html
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Re: [PATCH] fs: uselib - Set error on do_filp_open failure only

[Al Viro]

On Sun, Apr 22, 2012 at 03:19:43AM +0530, Sasikanth V wrote:
> At present "error" is set irrespective of do_filp_open failed or not.
> Setting error to PTR_ERR(file) on do_filp_open failure only.

NAK, since it's completely pointless.  PTR_ERR() is safe to use on *any*
pointers; result won't be anything interesting unless IS_ERR() is true,
but PTR_ERR() itself can be evaluated just fine.