linux-kernel - Re: [PATCH] driver core: fix possible missing of device probe

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Date:	Fri, 28 Sep 2012 15:13:38 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Ming Lei <ming.lei@...onical.com>
Cc:	anish singh <anish198519851985@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] driver core: fix possible missing of device probe

On Fri, Sep 28, 2012 at 10:07:22PM +0800, Ming Lei wrote:
> On Fri, Sep 28, 2012 at 9:55 PM, Russell King - ARM Linux
> <linux@....linux.org.uk> wrote:
> >> I do not mention threads case in one CPU because the context in
> >> which device_add runs will always see the driver added into
> >
> > There you go again.  Look at my _much_ better description of the problem
> > and you'll notice that device_add has nothing to do with this.
> 
> OK, I explain it again:
> 
> CPU0						CPU1
> 
> driver_register
> 	...
> 	bus_add_driver
> 		driver_attach
> 						device_add(devb)
> 
> 		klist_add_tail(klist_drivers)
> 
> When device_add(devb) is run just after completion of driver_attach
> and before klist_add_tail(klist_drivers), the 'devb' can't be probed
> in device_add because the driver hasn't been added into bus,
> and it wasn't be probed in driver_attach because driver_attach didn't
> see the device in the bus.
> 
> So the 'devb' will be missed to be probed in the bus, won't it?

Wait a moment.  You're describing a *totally* *different* problem to
the problem I reported.  I say - for the third time - that in the
problem I reported, device_add() has NOTHING TO DO WITH IT.

In your previous mail, you complained that my description did not
cover another case.  I throw that back at you and say to you that
_your_ description does _not_ cover my case, but refers to a
_different_ problem which happens to be fixed by the _same_ fix.

To attach my "reported-by" to a problem description which is not
the problem that I reported is bad practice, and actually creates
a lie.  If you wish to keep your problem description, then you must
remove my Reported-by, because the problem you refer to in your
description is not _my_ problem.
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