From: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
To: Matthew Wilcox <matthew@wil.cx>
Cc: linux-scsi <linux-scsi@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
James Bottomley <James.Bottomley@suse.de>,
Jeff Garzik <jeff@garzik.org>, Christoph Hellwig <hch@lst.de>,
FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>,
Hannes Reinecke <hare@suse.de>,
Mike Christie <michaelc@cs.wisc.edu>,
Open iSCSI <open-iscsi@googlegroups.com>
Subject: Re: [PATCH 01/12] libiscsi: Convert to host_lock less w/ interrupts disabled internally
Date: Mon, 20 Dec 2010 01:30:13 -0800 [thread overview]
Message-ID: <1292837413.20840.47.camel@haakon2.linux-iscsi.org> (raw)
In-Reply-To: <20101220020758.GK1263@parisc-linux.org>
On Sun, 2010-12-19 at 19:07 -0700, Matthew Wilcox wrote:
> On Sun, Dec 19, 2010 at 05:22:06PM -0800, Nicholas A. Bellinger wrote:
> > Actually sorry, Mike Christie did already make a clarification on this
> > subject here:
> >
> > http://marc.info/?l=linux-scsi&m=129010439421506&w=2
> >
> > I had originally thought the same that session->lock should be using
> > some flavour of spin_lock_irq*() as well, but apparently this is not the
> > case for libiscsi.
>
> Right, so it seems. "the session lock is just locked in softirqs/timers"
> means that it does need to be the _bh() version of spin_lock though.
>
> I'm actually not sure ... is it safe to use the _bh versions in BH
> context? I think it is because the preempt count is nested, unlike the
> _irq variants of spinlocks.
>
Hmmm, fair point. Merging the following incremental patch to convert
session->lock to use spin_lock_bh() in iscsi_queuecommand() into
lock_less-LLDs-for-38-v3:
commit 744f1c119b3fb0c1a6b3c67a7b490e234d1a7e75
Author: Nicholas Bellinger <nab@linux-iscsi.org>
Date: Mon Dec 20 09:17:19 2010 +0000
libiscsi: Convert iscsi_queuecommand to use spin_lock_bh
This patch converts iscsi_queuecommand() code to obtain struct iscsi_session->lock
using spin_lock_bh() to properly handle bottom-half context operation.
Reported-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
After a quick audit of iscsi_session->lock usage, and I see that
iscsi_complete_pdu(), iscsi_tmf_timedout(), iscsi_eh_cmd_timed_out(),
iscsi_check_transport_timeouts() are using spin_lock(), and
iscsi_session_failure() and iscsi_conn_failure() are using
spin_lock_irqsave().
Mike and Hannes, would you guys mind commenting on this..? From what I
can determine these should all be converted to use spin_lock_bh(),
yes..?
--nab
next prev parent reply other threads:[~2010-12-20 9:36 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-19 21:21 [PATCH 00/12] LLD host_lock-less conversion status for .38 Nicholas A. Bellinger
2010-12-19 21:21 ` [PATCH 01/12] libiscsi: Convert to host_lock less w/ interrupts disabled internally Nicholas A. Bellinger
2010-12-19 23:38 ` Matthew Wilcox
2010-12-20 1:15 ` Nicholas A. Bellinger
2010-12-20 1:22 ` Nicholas A. Bellinger
2010-12-20 2:07 ` Matthew Wilcox
2010-12-20 9:30 ` Nicholas A. Bellinger [this message]
2010-12-21 0:36 ` Mike Christie
2010-12-23 21:23 ` Nicholas A. Bellinger
2010-12-27 3:44 ` Mike Christie
2010-12-21 0:42 ` Mike Christie
2010-12-21 10:53 ` Boaz Harrosh
2010-12-21 23:43 ` Mike Christie
2010-12-23 21:33 ` Nicholas A. Bellinger
2010-12-19 21:21 ` [PATCH 02/12] scsi: Add IRQ_DISABLE_SCSI_QCMD wrapper Nicholas A. Bellinger
2010-12-20 10:48 ` Christoph Hellwig
2010-12-19 21:21 ` [PATCH 03/12] libsas: Convert to host_lock less w/ interrupts disabled externally Nicholas A. Bellinger
2010-12-20 8:58 ` Boaz Harrosh
2010-12-20 9:33 ` Nicholas A. Bellinger
2010-12-19 21:21 ` [PATCH 04/12] message: " Nicholas A. Bellinger
2010-12-19 21:22 ` [PATCH 05/12] fnic: " Nicholas A. Bellinger
2010-12-19 21:22 ` [PATCH 06/12] lpfc: " Nicholas A. Bellinger
2010-12-19 21:22 ` [PATCH 07/12] qla2xxx: " Nicholas A. Bellinger
2010-12-19 23:11 ` Matthew Wilcox
2010-12-20 0:19 ` Jeff Garzik
2010-12-20 1:07 ` Nicholas A. Bellinger
2010-12-20 9:23 ` Nicholas A. Bellinger
2010-12-21 0:37 ` Madhu Iyengar
2010-12-23 21:49 ` Nicholas A. Bellinger
2010-12-19 21:22 ` [PATCH 08/12] qla4xxx: " Nicholas A. Bellinger
2010-12-19 21:22 ` [PATCH 09/12] scsi_debug: Convert to host_lock less Nicholas A. Bellinger
2010-12-19 21:22 ` [PATCH 10/12] megaraid_sas: Add smp_mb__after_atomic_*() for instance->fw_outstanding Nicholas A. Bellinger
2010-12-19 21:22 ` [PATCH 11/12] megaraid_sas: Convert instance->issuepend_done to atomic_t Nicholas A. Bellinger
2010-12-19 21:22 ` [PATCH 12/12] megaraid_sas: Convert SHT->queuecommand() to run host_lock-less Nicholas A. Bellinger
2010-12-20 15:08 ` [PATCH 00/12] LLD host_lock-less conversion status for .38 Desai, Kashyap
2010-12-20 19:33 ` adam radford
2010-12-23 21:17 ` Nicholas A. Bellinger
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