linux-kernel - Re: [PATCH 0/2] hwrng: revert managed API changes for amd and geode

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Message-ID: <20170316095333.GB12039@gondor.apana.org.au>
Date:   Thu, 16 Mar 2017 17:53:33 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Prarit Bhargava <prarit@...hat.com>
Cc:     linux-kernel@...r.kernel.org, Matt Mackall <mpm@...enic.com>,
        Corentin LABBE <clabbe.montjoie@...il.com>,
        PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>,
        Wei Yongjun <weiyongjun1@...wei.com>,
        linux-crypto@...r.kernel.org, linux-geode@...ts.infradead.org
Subject: Re: [PATCH 0/2] hwrng: revert managed API changes for amd and geode

On Tue, Mar 14, 2017 at 07:36:00AM -0400, Prarit Bhargava wrote:
> When booting top-of-tree the following WARN_ON triggers in the kernel on
> a 15h AMD system.
> 
> WARNING: CPU: 2 PID: 621 at drivers/base/dd.c:349 driver_probe_device+0x38c
> Modules linked in: i2c_amd756(+) amd_rng sg pcspkr parport_pc(+) parport k8
> CPU: 2 PID: 621 Comm: systemd-udevd Not tainted 4.11.0-0.rc1.git0.1.el7_UNS
> Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./TYAN High-End 
> Call Trace:
> dump_stack+0x63/0x8e
> __warn+0xd1/0xf0
> warn_slowpath_null+0x1d/0x20
> driver_probe_device+0x38c/0x470
> __driver_attach+0xc9/0xf0
> ? driver_probe_device+0x470/0x470
> bus_for_each_dev+0x5d/0x90
> driver_attach+0x1e/0x20
> bus_add_driver+0x1d0/0x290
> driver_register+0x60/0xe0
> ? 0xffffffffa0037000
> __pci_register_driver+0x4c/0x50
> amd756_driver_init+0x1e/0x1000 [i2c_amd756]
> do_one_initcall+0x51/0x1b0
> ? __vunmap+0x85/0xd0
> ? do_init_module+0x27/0x1fa
> do_init_module+0x60/0x1fa
> load_module+0x15d1/0x1ad0
> ? m_show+0x1c0/0x1c0
> SYSC_finit_module+0xa9/0xd0
> 
> There are PCI devices that contain both a RNG and SMBUS device.  The
> RNG device is initialized by the amd-rng driver but the driver does not
> register against the device.  The SMBUS device is initialized by the
> i2c-amd756 driver and registers against the device and hits the WARN_ON()
> because the amd-rng driver has already allocated resources against the
> device.
> 
> The amd-rng driver was incorrectly migrated to the device resource model
> (devres), and after code inspection I found that the geode-rng driver was also
> incorrectly migrated.  These drivers are using devres but do not register a
> driver against the device, and both drivers are expecting a memory cleanup on
> a driver detach that will never happen.  This results in a memory leak when the
> driver is unloaded and the inability to reload the driver.
> 
> Revert 31b2a73c9c5f ("hwrng: amd - Migrate to managed API"), and 6e9b5e76882c
> ("hwrng: geode - Migrate to managed API").
> 
> Signed-off-by: Prarit Bhargava <prarit@...hat.com>
> Fixes: 31b2a73c9c5f ("hwrng: amd - Migrate to managed API").
> Fixes: 6e9b5e76882c ("hwrng: geode - Migrate to managed API")
> Cc: Matt Mackall <mpm@...enic.com>
> Cc: Herbert Xu <herbert@...dor.apana.org.au>
> Cc: Corentin LABBE <clabbe.montjoie@...il.com>
> Cc: PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>
> Cc: Wei Yongjun <weiyongjun1@...wei.com>
> Cc: linux-crypto@...r.kernel.org
> Cc: linux-geode@...ts.infradead.org

Both patches applied.  Thanks.
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt