linux-kernel - [RFC v4 02/19] libiscsi: Remove host_lock unlock() + lock() from iscsi

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Date:	Mon, 27 Sep 2010 19:05:23 -0700
From:	"Nicholas A. Bellinger" <nab@...ux-iscsi.org>
To:	linux-scsi <linux-scsi@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Vasu Dev <vasu.dev@...ux.intel.com>,
	Tim Chen <tim.c.chen@...ux.intel.com>,
	Andi Kleen <ak@...ux.intel.com>,
	Matthew Wilcox <willy@...ux.intel.com>,
	James Bottomley <James.Bottomley@...e.de>,
	Mike Christie <michaelc@...wisc.edu>,
	Jens Axboe <jaxboe@...ionio.com>
Cc:	James Smart <james.smart@...lex.com>,
	Andrew Vasquez <andrew.vasquez@...gic.com>,
	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
	Hannes Reinecke <hare@...e.de>,
	Joe Eykholt <jeykholt@...co.com>,
	Christoph Hellwig <hch@....de>,
	Jon Hawley <warthog9@...nel.org>,
	MPTFusionLinux <DL-MPTFusionLinux@....com>,
	"eata.c maintainer" <dario.ballabio@...ind.it>,
	Luben Tuikov <ltuikov@...oo.com>,
	mvsas maintainer <kewei@...vell.com>,
	pm8001 maintainer Jack Wang <jack_wang@...sh.com>,
	Nicholas Bellinger <nab@...ux-iscsi.org>
Subject: [RFC v4 02/19] libiscsi: Remove host_lock unlock() + lock() from iscsi_queuecommand()

From: Nicholas Bellinger <nab@...ux-iscsi.org>

This patch removes the now legacy host_lock unlock() + lock() optimization
from libiscsi.c:iscsi_queuecommand().  This also adds SHT->unlocked_qcmd=1
to signal host_lock less operation with iscsi_queuecommand().

Signed-off-by: Nicholas A. Bellinger <nab@...ux-iscsi.org>
---
 drivers/scsi/iscsi_tcp.c |    1 +
 drivers/scsi/libiscsi.c  |    4 ----
 2 files changed, 1 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index fec47de..f5933dd 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -882,6 +882,7 @@ static struct scsi_host_template iscsi_sw_tcp_sht = {
 	.target_alloc		= iscsi_target_alloc,
 	.proc_name		= "iscsi_tcp",
 	.this_id		= -1,
+	.unlocked_qcmd		= 1,
 };
 
 static struct iscsi_transport iscsi_sw_tcp_transport = {
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 633e090..7e4134e 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -1615,7 +1615,6 @@ int iscsi_queuecommand(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
 
 	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 +1705,6 @@ int iscsi_queuecommand(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
 
 	session->queued_cmdsn++;
 	spin_unlock(&session->lock);
-	spin_lock(host->host_lock);
 	return 0;
 
 prepd_reject:
@@ -1716,7 +1714,6 @@ 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:
@@ -1733,7 +1730,6 @@ fault:
 		scsi_in(sc)->resid = scsi_in(sc)->length;
 	}
 	done(sc);
-	spin_lock(host->host_lock);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(iscsi_queuecommand);
-- 
1.7.3

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