Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932563Ab0LSXil (ORCPT ); Sun, 19 Dec 2010 18:38:41 -0500 Received: from palinux.external.hp.com ([192.25.206.14]:33778 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932537Ab0LSXij (ORCPT ); Sun, 19 Dec 2010 18:38:39 -0500 Date: Sun, 19 Dec 2010 16:38:36 -0700 From: Matthew Wilcox To: "Nicholas A. Bellinger" Cc: linux-scsi , linux-kernel , James Bottomley , Jeff Garzik , Christoph Hellwig , FUJITA Tomonori , Hannes Reinecke , Mike Christie , Mike Anderson , Tejun Heo , Vasu Dev , Tim Chen , Andi Kleen , Ravi Anand , Andrew Vasquez , Joe Eykholt , James Smart , Douglas Gilbert , adam radford , Kashyap Desai , MPTFusionLinux Subject: Re: [PATCH 01/12] libiscsi: Convert to host_lock less w/ interrupts disabled internally Message-ID: <20101219233835.GJ1263@parisc-linux.org> References: <1292793727-31957-1-git-send-email-nab@linux-iscsi.org> <1292793727-31957-2-git-send-email-nab@linux-iscsi.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1292793727-31957-2-git-send-email-nab@linux-iscsi.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3666 Lines: 105 On Sun, Dec 19, 2010 at 01:21:56PM -0800, Nicholas A. Bellinger wrote: > This patch changes iscsi_queuecommand_lck() to a host_lock less > iscsi_queuecommand() that will internally disable interrupts using > session->lock and drop the now legacy host_lock unlock. I think this patch is buggy. Before, iscsi_queuecommand_lck is called with interrupts disabled. Now, it's called with interrupts disabled. Elsewhere, session->lock is acquired with bh's disabled: void iscsi_put_task(struct iscsi_task *task) { struct iscsi_session *session = task->conn->session; spin_lock_bh(&session->lock); So I think you need to convert the spin_lock(&session->lock); in iscsi_queuecommand_lck to at least a spin_lock_bh, and possibly a spin_lock_irq -- it's not clear to me whether it needs to exclude against interrupt context, or only BH context. In some places, it's taken with spin_lock_irqsave(). I'd play it safe and use _irq, but someone more confident with this code might choose to only use _bh. > Signed-off-by: Nicholas A. Bellinger > --- > drivers/scsi/libiscsi.c | 10 ++-------- > 1 files changed, 2 insertions(+), 8 deletions(-) > > diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c > index c15fde8..5535782 100644 > --- a/drivers/scsi/libiscsi.c > +++ b/drivers/scsi/libiscsi.c > @@ -1599,7 +1599,7 @@ enum { > FAILURE_SESSION_NOT_READY, > }; > > -static int iscsi_queuecommand_lck(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *)) > +int iscsi_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc) > { > struct iscsi_cls_session *cls_session; > struct Scsi_Host *host; > @@ -1609,13 +1609,11 @@ static int iscsi_queuecommand_lck(struct scsi_cmnd *sc, void (*done)(struct scsi > struct iscsi_conn *conn; > struct iscsi_task *task = NULL; > > - sc->scsi_done = done; > sc->result = 0; > sc->SCp.ptr = NULL; > > host = sc->device->host; > ihost = shost_priv(host); > - spin_unlock(host->host_lock); > > cls_session = starget_to_session(scsi_target(sc->device)); > session = cls_session->dd_data; > @@ -1706,7 +1704,6 @@ static int iscsi_queuecommand_lck(struct scsi_cmnd *sc, void (*done)(struct scsi > > session->queued_cmdsn++; > spin_unlock(&session->lock); > - spin_lock(host->host_lock); > return 0; > > prepd_reject: > @@ -1716,7 +1713,6 @@ reject: > spin_unlock(&session->lock); > ISCSI_DBG_SESSION(session, "cmd 0x%x rejected (%d)\n", > sc->cmnd[0], reason); > - spin_lock(host->host_lock); > return SCSI_MLQUEUE_TARGET_BUSY; > > prepd_fault: > @@ -1732,12 +1728,10 @@ fault: > scsi_out(sc)->resid = scsi_out(sc)->length; > scsi_in(sc)->resid = scsi_in(sc)->length; > } > - done(sc); > - spin_lock(host->host_lock); > + sc->scsi_done(sc); > return 0; > } > > -DEF_SCSI_QCMD(iscsi_queuecommand) > EXPORT_SYMBOL_GPL(iscsi_queuecommand); > > int iscsi_change_queue_depth(struct scsi_device *sdev, int depth, int reason) > -- > 1.7.3.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step." -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/