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

[Alan Stern]

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.

Alan Stern