linux-kernel - Re: [PATCH 2/4 net] qca_spi: Fix SPI IRQ handling

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Message-ID: <9e2bba3c98cd24ebf1b6d9fde2e0b9229ad6b99f.camel@redhat.com>
Date:   Fri, 24 Nov 2023 16:33:04 +0100
From:   Paolo Abeni <pabeni@...hat.com>
To:     Stefan Wahren <wahrenst@....net>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Lino Sanfilippo <LinoSanfilippo@....de>,
        Florian Fainelli <f.fainelli@...il.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4 net] qca_spi: Fix SPI IRQ handling

On Fri, 2023-11-24 at 15:01 +0100, Stefan Wahren wrote:
> Hi Paolo,
> 
> Am 23.11.23 um 12:37 schrieb Paolo Abeni:
> > On Tue, 2023-11-21 at 17:30 +0100, Stefan Wahren wrote:
> > > The functions qcaspi_netdev_open/close are responsible of request &
> > > free of the SPI interrupt, which wasn't the best choice. Currently
> > > it's possible to trigger a double free of the interrupt by calling
> > > qcaspi_netdev_close() after qcaspi_netdev_open() has failed.
> > > So let us split IRQ allocation & enabling, so we can take advantage
> > > of a device managed IRQ and also fix the issue.
> > > 
> > > Fixes: 291ab06ecf67 ("net: qualcomm: new Ethernet over SPI driver for QCA7000")
> > > Signed-off-by: Stefan Wahren <wahrenst@....net>
> > The change makes sense, but the changelog is confusing.
> > 
> > qcaspi_netdev_close() and qcaspi_netdev_open() are invoked only via
> > ndo_open and ndo_close(), right? So qcaspi_netdev_close() will never be
> > invoked qcaspi_netdev_open(), failure - that is when IFF_UP is not set.
> sorry, i missed to mention an important part. This issue is partly
> connected to patch 3.
> Please look at qcaspi_set_ringparam() which also call ndo_close() and
> ndo_open(). 

Ah, I see it now. IMHO root cause of the problem is there. The ethtool
op should not flip the device state. 

A more narrow fix would be to park/unpark the thread inside
set_ringparam() - instead of the whole patch 1 && 2 I suspect.

IMHO the changes in this still make sense - a refactor for net-next.

Cheers,

Paolo