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

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Message-Id: <20160301171550.GA29081@kroah.com>
Date:	Tue, 01 Mar 2016 17:15:54 +0000
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Dmitry Vyukov <dvyukov@...gle.com>
Cc:	xinhui <xinhui@...ux.vnet.ibm.com>, Jiri Slaby <jslaby@...e.cz>,
	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 Tue, Mar 01, 2016 at 10:03:30AM +0100, Dmitry Vyukov wrote:
> On Tue, Mar 1, 2016 at 6:01 AM, Greg Kroah-Hartman
> <gregkh@...uxfoundation.org> wrote:
> > On Sun, Feb 28, 2016 at 05:16:15PM +0100, Dmitry Vyukov wrote:
> >> 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?
> >
> > merge what?  I don't see any patch here or in my queue for this :(
> 
> 
> "[PATCH] TTY: n_gsm, fix false positive WARN_ON" from Jiri Slaby:
> https://lkml.org/lkml/2015/11/24/600
> 
> FWIW I have it in my tree for 3 months. Warnings have gone. No issues noticed.

I don't see it in my queue, nor in Linus's tree, so someone needs to
resend it if they want it merged into the kernel tree...

{hint}