netdev - Re: [PATCH] network: wireless: p54u: Fix race between disconnect and firmware loading

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Message-ID: <875zpu4pp4.fsf@kamboji.qca.qualcomm.com>
Date:   Tue, 28 May 2019 17:29:59 +0300
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Alan Stern <stern@...land.harvard.edu>
Cc:     Christian Lamparter <chunkeey@...il.com>,
        syzbot <syzbot+200d4bb11b23d929335f@...kaller.appspotmail.com>,
        <davem@...emloft.net>, <andreyknvl@...gle.com>,
        <syzkaller-bugs@...glegroups.com>,
        Kernel development list <linux-kernel@...r.kernel.org>,
        USB list <linux-usb@...r.kernel.org>,
        <linux-wireless@...r.kernel.org>, <netdev@...r.kernel.org>
Subject: Re: [PATCH] network: wireless: p54u: Fix race between disconnect and firmware loading

Alan Stern <stern@...land.harvard.edu> writes:

> On Tue, 28 May 2019, Kalle Valo wrote:
>
>> The correct prefix is "p54:", but I can fix that during commit.
>
> Oh, okay, thanks.
>
>> > Index: usb-devel/drivers/net/wireless/intersil/p54/p54usb.c
>> > ===================================================================
>> > --- usb-devel.orig/drivers/net/wireless/intersil/p54/p54usb.c
>> > +++ usb-devel/drivers/net/wireless/intersil/p54/p54usb.c
>> > @@ -33,6 +33,8 @@ MODULE_ALIAS("prism54usb");
>> >  MODULE_FIRMWARE("isl3886usb");
>> >  MODULE_FIRMWARE("isl3887usb");
>> >  
>> > +static struct usb_driver p54u_driver;
>> 
>> How is it safe to use static variables from a wireless driver? For
>> example, what if there are two p54 usb devices on the host? How do we
>> avoid a race in that case?
>
> There is no race.  This structure is not per-device; it refers only to
> the driver.  In fact, the line above is only a forward declaration --
> the actual definition of p54u_driver was already in the source file.

Ah, I missed that. Thanks!

-- 
Kalle Valo