From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Finn Thain <fthain@linux-m68k.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-m68k@lists.linux-m68k.org, linux-kernel@vger.kernel.org,
kernel@pengutronix.de
Subject: Re: [PATCH 1/5] nubus: Simplify check in remove callback
Date: Tue, 27 Jul 2021 13:42:20 +0200 [thread overview]
Message-ID: <20210727114220.7drjl6xvvlwetaod@pengutronix.de> (raw)
In-Reply-To: <d74ccd1-116d-9450-5ee4-8d5074998872@linux-m68k.org>
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On Tue, Jul 27, 2021 at 07:50:39PM +1000, Finn Thain wrote:
> On Tue, 27 Jul 2021, Uwe Kleine-König wrote:
>
> > The driver core only calls a remove callback when the device was
> > successfully bound (aka probed) before. So dev->driver is never NULL.
>
> Are you sure dev->driver is non-NULL for the lifetime of the device?
> A quick glance at device_reprobe() makes me wonder about that.
Not for the lifetime of the device, but as long as a driver is bound to
the device. device_reprobe() calls device_driver_detach() after which
the driver is considered unbound and dev->driver is assigned NULL. (via
device_driver_detach -> device_release_driver_internal ->
__device_release_driver)
> > Apart from that, the compiler might already assume dev->driver being
> > non-NULL after to_nubus_driver(dev->driver) was called.
>
> I don't understand how a compiler can make that assumption. But then, I
> don't know why compilers do a lot of the things they do...
Ah, you're right, there is no dereference in container_of, so I might
also be wrong here. I will send a v2 without this last sentence in the
commit log.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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next prev parent reply other threads:[~2021-07-27 11:42 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-27 8:08 [PATCH 0/5] Some cleanups after making bus_type::remove return void Uwe Kleine-König
2021-07-27 8:08 ` [PATCH 1/5] nubus: Simplify check in remove callback Uwe Kleine-König
2021-07-27 9:50 ` Finn Thain
2021-07-27 10:07 ` Geert Uytterhoeven
2021-07-27 10:19 ` Finn Thain
2021-07-27 11:42 ` Uwe Kleine-König [this message]
2021-07-31 10:32 ` Finn Thain
2021-07-31 12:05 ` Uwe Kleine-König
2021-07-27 8:08 ` [PATCH 2/5] nubus: Make struct nubus_driver::remove return void Uwe Kleine-König
2021-07-27 9:47 ` Finn Thain
2021-07-27 8:08 ` [PATCH 3/5] sh: superhyway: Simplify check in remove callback Uwe Kleine-König
2021-07-27 8:08 ` [PATCH 4/5] zorro: Simplify " Uwe Kleine-König
2021-07-27 8:08 ` [PATCH 5/5] zorro: Drop useless (and hardly used) .driver member in struct zorro_dev Uwe Kleine-König
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