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 11:23:07 +0400
From:	Michael Tokarev <mjt@....msk.ru>
To:	Ian Kent <raven@...maw.net>
CC:	Tim Gardner <tim.gardner@...onical.com>,
	linux-kernel@...r.kernel.org, autofs@...r.kernel.org
Subject: Re: [PATCH linux-next] autofs4: autofs4_catatonic_mode(): remove
 redundant null check on kfree()

13.02.2013 11:20, Ian Kent wrote:
> 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.

Ian, this is about something else really.  The patch is about the
NULL check before calling kfree() -- it does the NULL check internally.
It is nothing about code flow or anything else, it is about calling
kfree() unconditionally regardless whenever the argument is actually
NULL or non-NULL.  It makes the code shorter and easier to read.

You can add my

Signed-off-by: Michael Tokarev <mjt@....msk.ru>

if you want.

>> 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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