From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cornelia Huck Subject: Re: Possible problem with device_move() Date: Tue, 31 Jul 2007 10:33:05 +0200 Message-ID: <20070731103305.39b76a5d@gondolin.boeblingen.de.ibm.com> References: <20070730084229.1df8757c@gondolin.boeblingen.de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: Alan Stern Cc: Marcel Holtmann , Linux-pm mailing list List-Id: linux-pm@vger.kernel.org On Mon, 30 Jul 2007 13:34:35 -0400 (EDT), Alan Stern wrote: > As long as you never hold the device semaphores of both the parent and > the child there shouldn't be any problem. Could this happen when a > subchannel structure is deallocated? This is indeed what happens, since we unregister the child ccw_device from the (io_)subchannel's remove function. (We used to do unregistering of the ccw_device via a workqueue (in order to avoid livelocks on a no longer existing bus semaphore), but removed it since it seemed to be needlessly complicated code.)