From: Tejun Heo <htejun@gmail.com>
Date: Tue, 20 Feb 2007 14:27:06 +0000 (+0900)
Subject: libata: fix ata_scmd_need_defer()
X-Git-Tag: v2.6.21-rc2~25^2~36
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fcf1bf1584647f9fd864c193fee81840c4c5ce41;p=linux-2.6

libata: fix ata_scmd_need_defer()

Fix ata_scmd_need_defer() such that...

* whether NCQ is used or not is exactly determined using the same
  criteria as the issue path.

* defer-check is performed in all cases.

This fixes race condition where turning off NCQ on the fly causes
non-NCQ commands sneak into NCQ phase.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
---

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 7bb782b5ce..aa6cb6dcec 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1496,11 +1496,9 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc)
 static int ata_scmd_need_defer(struct ata_device *dev, int is_io)
 {
 	struct ata_port *ap = dev->ap;
+	int is_ncq = is_io && ata_ncq_enabled(dev);
 
-	if (!(dev->flags & ATA_DFLAG_NCQ))
-		return 0;
-
-	if (is_io) {
+	if (is_ncq) {
 		if (!ata_tag_valid(ap->active_tag))
 			return 0;
 	} else {