netdev - RE: [PATCH net v2] net: dsa: mv88e6xxx: lock mutex when freeing IRQs

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Date:   Wed, 27 Sep 2017 16:40:34 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Andrew Lunn' <andrew@...n.ch>
CC:     'Vivien Didelot' <vivien.didelot@...oirfairelinux.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel@...oirfairelinux.com" <kernel@...oirfairelinux.com>,
        "David S. Miller" <davem@...emloft.net>,
        Florian Fainelli <f.fainelli@...il.com>
Subject: RE: [PATCH net v2] net: dsa: mv88e6xxx: lock mutex when freeing IRQs

From: Andrew Lunn
> Sent: 27 September 2017 14:07
> To: David Laight
> On Wed, Sep 27, 2017 at 09:06:01AM +0000, David Laight wrote:
> > From: Vivien Didelot
> > > Sent: 26 September 2017 19:57
> > > mv88e6xxx_g2_irq_free locks the registers mutex, but not
> > > mv88e6xxx_g1_irq_free, which results in a stack trace from
> > > assert_reg_lock when unloading the mv88e6xxx module. Fix this.
> > >
> > > Fixes: 3460a5770ce9 ("net: dsa: mv88e6xxx: Mask g1 interrupts and free interrupt")
> > > Signed-off-by: Vivien Didelot <vivien.didelot@...oirfairelinux.com>
> > > ---
> > >  drivers/net/dsa/mv88e6xxx/chip.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
> > > index c6678aa9b4ef..e7ff7483d2fb 100644
> > > --- a/drivers/net/dsa/mv88e6xxx/chip.c
> > > +++ b/drivers/net/dsa/mv88e6xxx/chip.c
> > > @@ -3947,7 +3947,9 @@ static void mv88e6xxx_remove(struct mdio_device *mdiodev)
> > >  	if (chip->irq > 0) {
> > >  		if (chip->info->g2_irqs > 0)
> > >  			mv88e6xxx_g2_irq_free(chip);
> > > +		mutex_lock(&chip->reg_lock);
> > >  		mv88e6xxx_g1_irq_free(chip);
> > > +		mutex_unlock(&chip->reg_lock);
> >
> > Isn't the irq_free code likely to have to sleep waiting for any
> > ISR to complete??
> 
> Hi David
> 
> Possibly. But this is a mutex, not a spinlock. So sleeping is O.K.
> Or am i missing something?

Looks like I was missing some coffee :-)

	David