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Date: Thu, 1 Jun 2006 22:11:41 -0700
From: Andrew Morton <akpm@osdl.org>
To: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Cc: greg@kroah.com, linux-kernel@vger.kernel.org
Subject: Re: pci_walk_bus race condition
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On Fri, 02 Jun 2006 12:35:43 +0800
"Zhang, Yanmin" <yanmin_zhang@linux.intel.com> wrote:

> pci_walk_bus has a race with pci_destroy_dev. When cb is called
> in pci_walk_bus, pci_destroy_dev might unlink the dev pointed by next.
> Later on in the next loop, pointer next becomes NULL and cause
> kernel panic.
> 
> Below patch against 2.6.17-rc4 fixes it by changing pci_bus_lock (spin_lock)
> to pci_bus_sem (rw_semaphore).

How does s/spinlock/rwsem/ fix a race??