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From: Stefan Haberland <sth@linux.ibm.com>
To: axboe@kernel.dk
Cc: linux-block@vger.kernel.org, linux-s390@vger.kernel.org,
	hoeppner@linux.ibm.com, heiko.carstens@de.ibm.com,
	borntraeger@de.ibm.com, gor@linux.ibm.com
Subject: [PATCH 1/1] s390/dasd: fix endless loop after read unit address configuration
Date: Thu,  1 Aug 2019 13:06:30 +0200	[thread overview]
Message-ID: <20190801110630.82432-2-sth@linux.ibm.com> (raw)
In-Reply-To: <20190801110630.82432-1-sth@linux.ibm.com>

After getting a storage server event that causes the DASD device driver
to update its unit address configuration during a device shutdown there is
the possibility of an endless loop in the device driver.

In the system log there will be ongoing DASD error messages with RC: -19.

The reason is that the loop starting the ruac request only terminates when
the retry counter is decreased to 0. But in the sleep_on function there are
early exit paths that do not decrease the retry counter.

Prevent an endless loop by handling those cases separately.

Remove the unnecessary do..while loop since the sleep_on function takes
care of retries by itself.

Fixes: 8e09f21574ea ("[S390] dasd: add hyper PAV support to DASD device driver, part 1")
Cc: stable@vger.kernel.org # 2.6.25+
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>

---
 drivers/s390/block/dasd_alias.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/s390/block/dasd_alias.c b/drivers/s390/block/dasd_alias.c
index b9ce93e9df89..99f86612f775 100644
--- a/drivers/s390/block/dasd_alias.c
+++ b/drivers/s390/block/dasd_alias.c
@@ -383,6 +383,20 @@ suborder_not_supported(struct dasd_ccw_req *cqr)
 	char msg_format;
 	char msg_no;
 
+	/*
+	 * intrc values ENODEV, ENOLINK and EPERM
+	 * will be optained from sleep_on to indicate that no
+	 * IO operation can be started
+	 */
+	if (cqr->intrc == -ENODEV)
+		return 1;
+
+	if (cqr->intrc == -ENOLINK)
+		return 1;
+
+	if (cqr->intrc == -EPERM)
+		return 1;
+
 	sense = dasd_get_sense(&cqr->irb);
 	if (!sense)
 		return 0;
@@ -447,12 +461,8 @@ static int read_unit_address_configuration(struct dasd_device *device,
 	lcu->flags &= ~NEED_UAC_UPDATE;
 	spin_unlock_irqrestore(&lcu->lock, flags);
 
-	do {
-		rc = dasd_sleep_on(cqr);
-		if (rc && suborder_not_supported(cqr))
-			return -EOPNOTSUPP;
-	} while (rc && (cqr->retries > 0));
-	if (rc) {
+	rc = dasd_sleep_on(cqr);
+	if (rc && !suborder_not_supported(cqr)) {
 		spin_lock_irqsave(&lcu->lock, flags);
 		lcu->flags |= NEED_UAC_UPDATE;
 		spin_unlock_irqrestore(&lcu->lock, flags);
-- 
2.17.1


  reply	other threads:[~2019-08-01 11:06 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-01 11:06 [PATCH 0/1] sending DASD patches through linux-block Stefan Haberland
2019-08-01 11:06 ` Stefan Haberland [this message]
2019-08-02  2:47   ` [PATCH 1/1] s390/dasd: fix endless loop after read unit address configuration Jens Axboe
2019-08-02  2:47 ` [PATCH 0/1] sending DASD patches through linux-block Jens Axboe

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