linux-kernel - Re: [PATCH 4.4 51/79] bnxt_en: Fix for system hang if request

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Message-ID: <1536699932.3024.161.camel@codethink.co.uk>
Date:   Tue, 11 Sep 2018 22:05:32 +0100
From:   Ben Hutchings <ben.hutchings@...ethink.co.uk>
To:     Michael Chan <michael.chan@...adcom.com>
Cc:     Vikas Gupta <vikas.gupta@...adcom.com>, stable@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <alexander.levin@...rosoft.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4.4 51/79] bnxt_en: Fix for system hang if request_irq
 fails

On Tue, 2018-09-11 at 13:58 -0700, Michael Chan wrote:
> On Tue, Sep 11, 2018 at 1:14 PM, Ben Hutchings
> <ben.hutchings@...ethink.co.uk> wrote:
> > On Thu, 2018-08-23 at 09:53 +0200, Greg Kroah-Hartman wrote:
> > > 4.4-stable review patch.  If anyone has any objections, please
> > > let me know.
> > > 
> > > ------------------
> > > 
> > > From: Vikas Gupta <vikas.gupta@...adcom.com>
> > > 
> > > [ Upstream commit c58387ab1614f6d7fb9e244f214b61e7631421fc ]
> > > 
> > > Fix bug in the error code path when bnxt_request_irq() returns
> > > failure.
> > > bnxt_disable_napi() should not be called in this error path
> > > because
> > > NAPI has not been enabled yet.
> > 
> > [...]
> > > --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> > > +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> > > @@ -4591,7 +4591,7 @@ static int __bnxt_open_nic(struct bnxt *
> > >               rc = bnxt_request_irq(bp);
> > >               if (rc) {
> > >                       netdev_err(bp->dev, "bnxt_request_irq err:
> > > %x\n", rc);
> > > -                     goto open_err;
> > > +                     goto open_err_irq;
> > >               }
> > >       }
> > > 
> > > @@ -4629,6 +4629,8 @@ static int __bnxt_open_nic(struct bnxt *
> > > 
> > >  open_err:
> > >       bnxt_disable_napi(bp);
> > > +
> > > +open_err_irq:
> > >       bnxt_del_napi(bp);
> > 
> > Shouldn't this added statement be conditional on irq_re_init?
> > 
> 
> Unconditional call is more correct, because when open fails, we clean
> up everything, including the NAPI that was added just now or during a
> previous call.
> 
> In other words, the NAPI struct is always valid here whether
> irq_re_init is true or not.  And we always delete it if open fails.

OK, I see.

Ben.

-- 
Ben Hutchings, Software Developer                         Codethink Ltd
https://www.codethink.co.uk/                 Dale House, 35 Dale Street
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