Re: [PATCH] net: davicom: dm9000: Avoid spinlock recursion during dm9000_timeout routine

From	David Miller <davem@davemloft.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH] net: davicom: dm9000: Avoid spinlock recursion during dm9000_timeout routine
Date	2017-06-02 20:20 +0200
Message-ID	<tNZkZ-4FP-1@gated-at.bofh.it> (permalink)
References	<tNdzH-6yx-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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From: Liu Xiang <liu.xiang6@zte.com.cn>
Date: Wed, 31 May 2017 23:06:42 +0800

> On the DM9000B, dm9000_phy_write() is called after the main spinlock
> is held, during the dm9000_timeout() routine. Spinlock recursion
> occurs because the main spinlock is requested again in
> dm9000_phy_write(). So spinlock should be avoided in dm9000_phy_write()
> during the dm9000_timeout() routine.
> 
> Signed-off-by: Liu Xiang <liu.xiang6@zte.com.cn>

It think this is racy.

Now, during a timeout device reset, another thread of control can come
in and access phy registers without any synchronization whatsoever.

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[PATCH] net: davicom: dm9000: Avoid spinlock recursion during dm9000_timeout routine Liu Xiang <liu.xiang6@zte.com.cn> - 2017-05-31 17:20 +0200
  Re: [PATCH] net: davicom: dm9000: Avoid spinlock recursion during  dm9000_timeout routine David Miller <davem@davemloft.net> - 2017-06-02 20:20 +0200

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