linux-kernel - Re: [PATCH] cciss: return 0 from driver probe function on success, not 1

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Message-ID: <5273D4DE.6060802@kernel.dk>
Date:	Fri, 01 Nov 2013 10:20:46 -0600
From:	Jens Axboe <axboe@...nel.dk>
To:	"Stephen M. Cameron" <scameron@...rdog.cce.hp.com>
CC:	stephenmcameron@...il.com, akpm@...ux-foundation.org,
	mikem@...rdog.cce.hp.com, linux-kernel@...r.kernel.org,
	thenzl@...hat.com
Subject: Re: [PATCH] cciss: return 0 from driver probe function on success,
 not 1

On 11/01/2013 10:06 AM, Stephen M. Cameron wrote:
> From: Stephen M. Cameron <scameron@...rdog.cce.hp.com>
> 
> A return value of 1 is interpreted as an error.  See pci_driver.
> in local_pci_probe().  If you're wondering how this ever could
> have worked, it's because it used to be the case that only return
> values less than zero were interpreted as failure.  But even in
> the current kernel if the driver registers its various entry
> points with the kernel, and then returns a value which is
> interpreted as failure, those registrations aren't undone, so
> the driver still mostly works.  However, the driver's remove
> function wouldn't be called on rmmod, and pci power management
> functions wouldn't work.  In the case of Smart Array, since it
> has a battery backed cache (or else no cache) even if the driver
> is not shut down properly as long as there is no outstanding
> i/o, nothing too bad happens, which is why it took so long to
> notice.
> 
> Requesting backport to stable because the change to pci-driver.c
> which requires driver probe functions to return 0 occurred between
> 2.6.35 and 2.6.36 (the pci power management breakage) and again
> between 3.7 and 3.8 (pci_dev->driver getting set to NULL in
> local_pci_probe() preventing driver remove function from being
> called on rmmod.)

The original patch went in two days ago, so it's a little difficult for
me to update it unfortunately. But you can include lots of this in the
pci-driver.c warning print patch instead.

-- 
Jens Axboe

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