linux-kernel - Re: [PATCH] make consistent errno value when open pident vs exit(2) race

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Date:	Wed, 08 Apr 2009 20:35:31 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	Andrew Morton <akpm@...l.org>,
	Alexey Dobriyan <adobriyan@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] make consistent errno value when open pident vs exit(2) race

KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> writes:

> proc_pident_instantiate() has following call flow.
>
> proc_pident_lookup()
>   proc_pident_instantiate()
>     proc_pid_make_inode()
>
> And, proc_pident_lookup() has following error handling.
>
> 	const struct pid_entry *p, *last;
> 	error = ERR_PTR(-ENOENT);
> 	if (!task)
> 		goto out_no_task;
>
> Then, proc_pident_instantiate should return ENOENT too when racing against
> exit(2) occur.
>
> EINAL has two bad reason. 
>   - it implies caller is wrong. bad the race isn't caller's mistake. 
>   - man 2 open don't explain EINVAL. user often don't handle it.
>
>
> Note: Other proc_pid_make_inode() caller already use ENOENT properly.

Acked-by: "Eric W. Biederman" <ebiederm@...ssion.com>

Looks reasonable to me.


> Cc: Eric W. Biederman <ebiederm@...ssion.com>
> Cc: Andrew Morton <akpm@...l.org>
> Cc: Alexey Dobriyan <adobriyan@...il.com>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> --
>  fs/proc/base.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index f715597..803d09e 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -1953,7 +1953,7 @@ static struct dentry *proc_pident_instantiate(struct inode *dir,
>  	const struct pid_entry *p = ptr;
>  	struct inode *inode;
>  	struct proc_inode *ei;
> -	struct dentry *error = ERR_PTR(-EINVAL);
> +	struct dentry *error = ERR_PTR(-ENOENT);
>  
>  	inode = proc_pid_make_inode(dir->i_sb, task);
>  	if (!inode)
--
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