linux-kernel - Re: Linux 3.16: all my drivers on SPI bus report WARNING: at drivers/base/dd.c:286

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Message-ID: <CAOY=C6HxdLOPb6y=VCB_0VrSt_Vyc95nuMN_3ZDFSqoV=mAfEw@mail.gmail.com>
Date:	Thu, 28 Aug 2014 22:28:19 +0200
From:	Stijn Devriendt <highguy@...il.com>
To:	leroy christophe <christophe.leroy@....fr>
Cc:	Axel Lin <axel.lin@...ics.com>, Mark Brown <broonie@...aro.org>,
	LinuxPPC-dev <linuxppc-dev@...ts.ozlabs.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-spi@...r.kernel.org
Subject: Re: Linux 3.16: all my drivers on SPI bus report WARNING: at drivers/base/dd.c:286

On Thu, Aug 28, 2014 at 5:53 PM, leroy christophe
<christophe.leroy@....fr> wrote:
>
> I've been able to identify the origin of the issue. It happens since the below commit.
> Do you know what should be done to fix that ?
>
> Christophe
>
>

Actually, more things are wrong with what the driver is doing.
If inside spi_add_device() the call to device_add() fails, then that
code bails out without any call to spi_cleanup() and the same
memory will leak (Is this intended?).

Basically, fsl_spi_setup allocates memory using devm_kzalloc, while
device_add expects that any memory allocated via this way is only
done in the device's probe function.

The simple fix would be to do a normal allocation (revert the patch) and
add a free to the cleanup() function. Unfortunately that doesn't fix the
memleak I mentioned above.

So, some outside-the-box thinking brings me to conclude that another way
to fix this problem is to allocate the devm_kzalloc not on the device's
resource
list but on the controller's resources (it's controller state after all...).

Regards,
Stijn
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