linux-kernel - Re: [PATCH linux-next] autofs4: autofs4_catatonic_mode(): remove redundant null check on kfree()

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Date:	Wed, 13 Feb 2013 15:20:08 +0800
From:	Ian Kent <raven@...maw.net>
To:	Tim Gardner <tim.gardner@...onical.com>
Cc:	linux-kernel@...r.kernel.org, autofs@...r.kernel.org
Subject: Re: [PATCH linux-next] autofs4: autofs4_catatonic_mode(): remove
 redundant null check on kfree()

On Tue, 2013-02-12 at 10:12 -0700, Tim Gardner wrote:
> smatch analysis:
> 
> fs/autofs4/waitq.c:46 autofs4_catatonic_mode() info: redundant null
>  check on wq->name.name calling kfree()

I'm not sure about this change.

autofs4_catatonic_mode() could be called when there are remaining
entries in the wait queue, which is nulled, so autofs4_wait_release()
won't see the the discarded waits if it is called.

> 
> Cc: Ian Kent <raven@...maw.net>
> Cc: autofs@...r.kernel.org
> Signed-off-by: Tim Gardner <tim.gardner@...onical.com>
> ---
>  fs/autofs4/waitq.c |    6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
> index 03bc1d3..3db70da 100644
> --- a/fs/autofs4/waitq.c
> +++ b/fs/autofs4/waitq.c
> @@ -42,10 +42,8 @@ void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
>  	while (wq) {
>  		nwq = wq->next;
>  		wq->status = -ENOENT; /* Magic is gone - report failure */
> -		if (wq->name.name) {
> -			kfree(wq->name.name);
> -			wq->name.name = NULL;
> -		}
> +		kfree(wq->name.name);
> +		wq->name.name = NULL;
>  		wq->wait_ctr--;
>  		wake_up_interruptible(&wq->queue);
>  		wq = nwq;


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