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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Julian Wiedmann <jwi@linux.vnet.ibm.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.16 074/279] s390/qeth: fix request-side race during cmd IO timeout
Date:   Mon, 18 Jun 2018 10:10:59 +0200
Message-Id: <20180618080611.886474287@linuxfoundation.org>
In-Reply-To: <20180618080608.851973560@linuxfoundation.org>
References: <20180618080608.851973560@linuxfoundation.org>
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4.16-stable review patch.  If anyone has any objections, please let me know.

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

From: Julian Wiedmann <jwi@linux.vnet.ibm.com>

[ Upstream commit db71bbbd11a4d314f0fa3fbf3369b71cf33ce33c ]

Submitting a cmd IO request (usually on the WRITE device, but for IDX
also on the READ device) is currently done with ccw_device_start()
and a manual timeout in the caller.
On timeout, the caller cleans up the related resources (eg. IO buffer).
But 1) the IO might still be active and utilize those resources, and
    2) when the IO completes, qeth_irq() will attempt to clean up the
       same resources again.

Instead of introducing additional resource locking, switch to
ccw_device_start_timeout() to ensure IO termination after timeout, and
let the IRQ handler alone deal with cleaning up after a request.

This also removes a stray write->irq_pending reset from
clear_ipacmd_list(). The routine doesn't terminate any pending IO on
the WRITE device, so this should be handled properly via IO timeout
in the IRQ handler.

Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/s390/net/qeth_core_main.c |   51 +++++++++++++++++++-------------------
 drivers/s390/net/qeth_core_mpc.h  |   12 ++++++++
 drivers/s390/net/qeth_l2_main.c   |    4 +-
 3 files changed, 40 insertions(+), 27 deletions(-)

--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -706,7 +706,6 @@ void qeth_clear_ipacmd_list(struct qeth_
 		qeth_put_reply(reply);
 	}
 	spin_unlock_irqrestore(&card->lock, flags);
-	atomic_set(&card->write.irq_pending, 0);
 }
 EXPORT_SYMBOL_GPL(qeth_clear_ipacmd_list);
 
@@ -1101,14 +1100,9 @@ static void qeth_irq(struct ccw_device *
 {
 	int rc;
 	int cstat, dstat;
+	struct qeth_cmd_buffer *iob = NULL;
 	struct qeth_channel *channel;
 	struct qeth_card *card;
-	struct qeth_cmd_buffer *iob;
-
-	if (__qeth_check_irb_error(cdev, intparm, irb))
-		return;
-	cstat = irb->scsw.cmd.cstat;
-	dstat = irb->scsw.cmd.dstat;
 
 	card = CARD_FROM_CDEV(cdev);
 	if (!card)
@@ -1126,6 +1120,19 @@ static void qeth_irq(struct ccw_device *
 		channel = &card->data;
 		QETH_CARD_TEXT(card, 5, "data");
 	}
+
+	if (qeth_intparm_is_iob(intparm))
+		iob = (struct qeth_cmd_buffer *) __va((addr_t)intparm);
+
+	if (__qeth_check_irb_error(cdev, intparm, irb)) {
+		/* IO was terminated, free its resources. */
+		if (iob)
+			qeth_release_buffer(iob->channel, iob);
+		atomic_set(&channel->irq_pending, 0);
+		wake_up(&card->wait_q);
+		return;
+	}
+
 	atomic_set(&channel->irq_pending, 0);
 
 	if (irb->scsw.cmd.fctl & (SCSW_FCTL_CLEAR_FUNC))
@@ -1149,6 +1156,10 @@ static void qeth_irq(struct ccw_device *
 		/* we don't have to handle this further */
 		intparm = 0;
 	}
+
+	cstat = irb->scsw.cmd.cstat;
+	dstat = irb->scsw.cmd.dstat;
+
 	if ((dstat & DEV_STAT_UNIT_EXCEP) ||
 	    (dstat & DEV_STAT_UNIT_CHECK) ||
 	    (cstat)) {
@@ -1187,11 +1198,8 @@ static void qeth_irq(struct ccw_device *
 	    channel->state == CH_STATE_UP)
 		__qeth_issue_next_read(card);
 
-	if (intparm) {
-		iob = (struct qeth_cmd_buffer *) __va((addr_t)intparm);
-		if (iob->callback)
-			iob->callback(iob->channel, iob);
-	}
+	if (iob && iob->callback)
+		iob->callback(iob->channel, iob);
 
 out:
 	wake_up(&card->wait_q);
@@ -1862,8 +1870,8 @@ static int qeth_idx_activate_get_answer(
 		   atomic_cmpxchg(&channel->irq_pending, 0, 1) == 0);
 	QETH_DBF_TEXT(SETUP, 6, "noirqpnd");
 	spin_lock_irqsave(get_ccwdev_lock(channel->ccwdev), flags);
-	rc = ccw_device_start(channel->ccwdev,
-			      &channel->ccw, (addr_t) iob, 0, 0);
+	rc = ccw_device_start_timeout(channel->ccwdev, &channel->ccw,
+				      (addr_t) iob, 0, 0, QETH_TIMEOUT);
 	spin_unlock_irqrestore(get_ccwdev_lock(channel->ccwdev), flags);
 
 	if (rc) {
@@ -1880,7 +1888,6 @@ static int qeth_idx_activate_get_answer(
 	if (channel->state != CH_STATE_UP) {
 		rc = -ETIME;
 		QETH_DBF_TEXT_(SETUP, 2, "3err%d", rc);
-		qeth_clear_cmd_buffers(channel);
 	} else
 		rc = 0;
 	return rc;
@@ -1934,8 +1941,8 @@ static int qeth_idx_activate_channel(str
 		   atomic_cmpxchg(&channel->irq_pending, 0, 1) == 0);
 	QETH_DBF_TEXT(SETUP, 6, "noirqpnd");
 	spin_lock_irqsave(get_ccwdev_lock(channel->ccwdev), flags);
-	rc = ccw_device_start(channel->ccwdev,
-			      &channel->ccw, (addr_t) iob, 0, 0);
+	rc = ccw_device_start_timeout(channel->ccwdev, &channel->ccw,
+				      (addr_t) iob, 0, 0, QETH_TIMEOUT);
 	spin_unlock_irqrestore(get_ccwdev_lock(channel->ccwdev), flags);
 
 	if (rc) {
@@ -1956,7 +1963,6 @@ static int qeth_idx_activate_channel(str
 		QETH_DBF_MESSAGE(2, "%s IDX activate timed out\n",
 			dev_name(&channel->ccwdev->dev));
 		QETH_DBF_TEXT_(SETUP, 2, "2err%d", -ETIME);
-		qeth_clear_cmd_buffers(channel);
 		return -ETIME;
 	}
 	return qeth_idx_activate_get_answer(channel, idx_reply_cb);
@@ -2158,8 +2164,8 @@ int qeth_send_control_data(struct qeth_c
 
 	QETH_CARD_TEXT(card, 6, "noirqpnd");
 	spin_lock_irqsave(get_ccwdev_lock(card->write.ccwdev), flags);
-	rc = ccw_device_start(card->write.ccwdev, &card->write.ccw,
-			      (addr_t) iob, 0, 0);
+	rc = ccw_device_start_timeout(CARD_WDEV(card), &card->write.ccw,
+				      (addr_t) iob, 0, 0, event_timeout);
 	spin_unlock_irqrestore(get_ccwdev_lock(card->write.ccwdev), flags);
 	if (rc) {
 		QETH_DBF_MESSAGE(2, "%s qeth_send_control_data: "
@@ -2191,8 +2197,6 @@ int qeth_send_control_data(struct qeth_c
 		}
 	}
 
-	if (reply->rc == -EIO)
-		goto error;
 	rc = reply->rc;
 	qeth_put_reply(reply);
 	return rc;
@@ -2203,9 +2207,6 @@ time_err:
 	list_del_init(&reply->list);
 	spin_unlock_irqrestore(&reply->card->lock, flags);
 	atomic_inc(&reply->received);
-error:
-	atomic_set(&card->write.irq_pending, 0);
-	qeth_release_buffer(iob->channel, iob);
 	rc = reply->rc;
 	qeth_put_reply(reply);
 	return rc;
--- a/drivers/s390/net/qeth_core_mpc.h
+++ b/drivers/s390/net/qeth_core_mpc.h
@@ -35,6 +35,18 @@ extern unsigned char IPA_PDU_HEADER[];
 #define QETH_HALT_CHANNEL_PARM	-11
 #define QETH_RCD_PARM -12
 
+static inline bool qeth_intparm_is_iob(unsigned long intparm)
+{
+	switch (intparm) {
+	case QETH_CLEAR_CHANNEL_PARM:
+	case QETH_HALT_CHANNEL_PARM:
+	case QETH_RCD_PARM:
+	case 0:
+		return false;
+	}
+	return true;
+}
+
 /*****************************************************************************/
 /* IP Assist related definitions                                             */
 /*****************************************************************************/
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -1346,8 +1346,8 @@ static int qeth_osn_send_control_data(st
 	qeth_prepare_control_data(card, len, iob);
 	QETH_CARD_TEXT(card, 6, "osnoirqp");
 	spin_lock_irqsave(get_ccwdev_lock(card->write.ccwdev), flags);
-	rc = ccw_device_start(card->write.ccwdev, &card->write.ccw,
-			      (addr_t) iob, 0, 0);
+	rc = ccw_device_start_timeout(CARD_WDEV(card), &card->write.ccw,
+				      (addr_t) iob, 0, 0, QETH_IPA_TIMEOUT);
 	spin_unlock_irqrestore(get_ccwdev_lock(card->write.ccwdev), flags);
 	if (rc) {
 		QETH_DBF_MESSAGE(2, "qeth_osn_send_control_data: "