linux-kernel - Re: [PATCH] TTY: n_gsm, fix false positive WARN

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Date:	Sun, 28 Feb 2016 17:16:15 +0100
From:	Dmitry Vyukov <dvyukov@...gle.com>
To:	xinhui <xinhui@...ux.vnet.ibm.com>
Cc:	Jiri Slaby <jslaby@...e.cz>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Alan Cox <alan@...ux.intel.com>,
	stable <stable@...r.kernel.org>
Subject: Re: [PATCH] TTY: n_gsm, fix false positive WARN_ON

On Wed, Nov 25, 2015 at 11:32 AM, xinhui <xinhui@...ux.vnet.ibm.com> wrote:
> hi, Jiri
>
> On 2015/11/25 17:56, Jiri Slaby wrote:
>>
>> Hi,
>>
>> On 11/25/2015, 07:32 AM, xinhui wrote:
>>>
>>>      This warning should blame on commit 5a640967 ("tty/n_gsm.c: fix a
>>> memory leak in gsmld_open()").
>>
>>
>> Oh, yes, I messed up the "Fixes" line then. It should write:
>> Fixes: 5a640967 ("tty/n_gsm.c: fix a memory leak in gsmld_open()")
>>
> that's Okay. :)
>
>>> I have one confusion. As there is field gsm->num to store the index of
>>> gsm_mux[]. so in gsm_cleanup_mux(), why we still use for-loop to find
>>> this mux?
>>>
>>> In error handle path, for example, the call trace in this patch, as we
>>> failed to activate it and the
>>> gsm->num is invalid(and the value is 0). we can just modify the codes
>>> like below:
>>>
>>> if(gsm_mux[gsm->num] == gsm)
>>> ....other work
>>> else
>>>      return;
>>>
>>> I think it would work, and the logic is correct. Or I just miss
>>> something important?
>>
>>
>> Yup, it looks like a cleanup. Could you prepare a separate patch for that?
>>
> yes, I will do that :)
>
>> Something like this:
>>          /* open failed before registering => nothing to do */
>>          if (gsm_mux[gsm->num] != gsm)
>>                return;
>>          spin_lock(&gsm_mux_lock);
>>          gsm_mux[gsm->num] = NULL;
>>          spin_unlock(&gsm_mux_lock);
>>
> looks pretty good, thanks.


This is still not merged and fires regularly for me. Can we please merge it?