linux-kernel - [PATCH 3.16 167/346] s390/dasd: fix hanging device after clear subchannel

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Message-ID: <lsq.1479082460.167566843@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:20 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Martin Schwidefsky" <schwidefsky@...ibm.com>,
        "Stefan Haberland" <sth@...ux.vnet.ibm.com>,
        "Sebastian Ott" <sebott@...ux.vnet.ibm.com>
Subject: [PATCH 3.16 167/346] s390/dasd: fix hanging device after clear
 subchannel

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Stefan Haberland <sth@...ux.vnet.ibm.com>

commit 9ba333dc55cbb9523553df973adb3024d223e905 upstream.

When a device is in a status where CIO has killed all I/O by itself the
interrupt for a clear request may not contain an irb to determine the
clear function. Instead it contains an error pointer -EIO.
This was ignored by the DASD int_handler leading to a hanging device
waiting for a clear interrupt.

Handle -EIO error pointer correctly for requests that are clear pending and
treat the clear as successful.

Signed-off-by: Stefan Haberland <sth@...ux.vnet.ibm.com>
Reviewed-by: Sebastian Ott <sebott@...ux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/s390/block/dasd.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -1613,9 +1613,18 @@ void dasd_int_handler(struct ccw_device
 	unsigned long long now;
 	int expires;
 
+	cqr = (struct dasd_ccw_req *) intparm;
 	if (IS_ERR(irb)) {
 		switch (PTR_ERR(irb)) {
 		case -EIO:
+			if (cqr && cqr->status == DASD_CQR_CLEAR_PENDING) {
+				device = (struct dasd_device *) cqr->startdev;
+				cqr->status = DASD_CQR_CLEARED;
+				dasd_device_clear_timer(device);
+				wake_up(&dasd_flush_wq);
+				dasd_schedule_device_bh(device);
+				return;
+			}
 			break;
 		case -ETIMEDOUT:
 			DBF_EVENT_DEVID(DBF_WARNING, cdev, "%s: "
@@ -1631,7 +1640,6 @@ void dasd_int_handler(struct ccw_device
 	}
 
 	now = get_tod_clock();
-	cqr = (struct dasd_ccw_req *) intparm;
 	/* check for conditions that should be handled immediately */
 	if (!cqr ||
 	    !(scsw_dstat(&irb->scsw) == (DEV_STAT_CHN_END | DEV_STAT_DEV_END) &&