linux-kernel - Re: [PATCH] driver core: fix shutdown races with probe/remove(v1)

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Message-ID: <4FD1DFDB.3020300@mvista.com>
Date:	Fri, 08 Jun 2012 15:19:55 +0400
From:	Sergei Shtylyov <sshtylyov@...sta.com>
To:	Ming Lei <ming.lei@...onical.com>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Alan Stern <stern@...land.harvard.edu>, stable@...r.kernel.org
Subject: Re: [PATCH] driver core: fix shutdown races with probe/remove(v1)

Hello.

On 08-06-2012 9:38, Ming Lei wrote:

> Firstly, .shutdown callback may touch a uninitialized hardware
> if dev->driver is set and .probe is not completed.

> Secondly, device_shutdown() may dereference a null pointer to cause
> oops when dev->driver is cleared after it is checked in
> device_shutdown().

> So just hold device lock and its parent lock if it has to fix the
> races.

> Cc: Alan Stern <stern@...land.harvard.edu>
> Cc: stable@...r.kernel.org
> Signed-off-by: Ming Lei <ming.lei@...onical.com>
> ---
>   drivers/base/core.c |    8 ++++++++
>   1 file changed, 8 insertions(+)

> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 346be8b..cbc8bd2 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -1820,6 +1820,11 @@ void device_shutdown(void)
>   		list_del_init(&dev->kobj.entry);
>   		spin_unlock(&devices_kset->list_lock);
>
> +		/*hold lock[s] to avoid races with .probe/.release*/

    Please add spaces after /* and before */. Or the applier please do it...

WBR, Sergei
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