From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753768AbdCOSpY (ORCPT ); Wed, 15 Mar 2017 14:45:24 -0400 Received: from mail.kernel.org ([198.145.29.136]:37846 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751487AbdCOSoH (ORCPT ); Wed, 15 Mar 2017 14:44:07 -0400 Date: Wed, 15 Mar 2017 11:44:01 -0700 (PDT) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-X260 To: Juergen Gross cc: Stefano Stabellini , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, boris.ostrovsky@oracle.com, Stefano Stabellini , Eric Van Hensbergen , Ron Minnich , Latchesar Ionkov , v9fs-developer@lists.sourceforge.net Subject: Re: [PATCH v3 4/7] xen/9pfs: connect to the backend In-Reply-To: Message-ID: References: <1489449019-13343-1-git-send-email-sstabellini@kernel.org> <1489449019-13343-4-git-send-email-sstabellini@kernel.org> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 15 Mar 2017, Juergen Gross wrote: > On 14/03/17 22:22, Stefano Stabellini wrote: > > Hi Juergen, > > > > thank you for the review! > > > > On Tue, 14 Mar 2017, Juergen Gross wrote: > >> On 14/03/17 00:50, Stefano Stabellini wrote: > >>> Implement functions to handle the xenbus handshake. Upon connection, > >>> allocate the rings according to the protocol specification. > >>> > >>> Initialize a work_struct and a wait_queue. The work_struct will be used > >>> to schedule work upon receiving an event channel notification from the > >>> backend. The wait_queue will be used to wait when the ring is full and > >>> we need to send a new request. > >>> > >>> Signed-off-by: Stefano Stabellini > >>> CC: boris.ostrovsky@oracle.com > >>> CC: jgross@suse.com > >>> CC: Eric Van Hensbergen > >>> CC: Ron Minnich > >>> CC: Latchesar Ionkov > >>> CC: v9fs-developer@lists.sourceforge.net > >>> --- > > >> Did you think about using request_threaded_irq() instead of a workqueue? > >> For an example see e.g. drivers/scsi/xen-scsifront.c > > > > I like workqueues :-) It might come down to personal preferences, but I > > think workqueues are more flexible and a better fit for this use case. > > Not only it is easy to schedule work in a workqueue from the interrupt > > handler, but also they can be used for sleeping in the request function > > if there is not enough room on the ring. Besides, they can easily be > > configured to share a single thread or to have multiple independent > > threads. > > I'm fine with the workqueues as long as you have decided to use them > considering the alternatives. :-) > > >> Can't you use xenbus_read_unsigned() instead of xenbus_read()? > > > > I can use xenbus_read_unsigned in the other cases below, but not here, > > because versions is in the form: "1,3,4" > > Is this documented somewhere? > > Hmm, are any of the Xenstore entries documented? Shouldn't this be done > in xen_9pfs.h ? They are documented in docs/misc/9pfs.markdown, under "Xenstore". Given that it's all written there, especially the semantics, I didn't repeat it in xen_9pfs.h