[3.16.y-ckt stable] Patch "s390/3215: fix hanging console issue" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    s390/3215: fix hanging console issue

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From b3ff4326765c5e72587041028b11e14d98bcadc6 Mon Sep 17 00:00:00 2001
From: Martin Schwidefsky <schwidefsky at de.ibm.com>
Date: Tue, 15 Jul 2014 17:53:12 +0200
Subject: s390/3215: fix hanging console issue

commit 26d766c60f4ea08cd14f0f3435a6db3d6cc2ae96 upstream.

The ccw_device_start in raw3215_start_io can fail. raw3215_try_io
does not check if the request could be started and removes any
pending timer. This can leave the system in a hanging state.
Check for pending request after raw3215_start_io and start a
timer if necessary.

Signed-off-by: Martin Schwidefsky <schwidefsky at de.ibm.com>
Cc: Ben Hutchings <ben at decadent.org.uk>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/s390/char/con3215.c | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/drivers/s390/char/con3215.c b/drivers/s390/char/con3215.c
index 5af7f0bd6125..a6d47e5eee9e 100644
--- a/drivers/s390/char/con3215.c
+++ b/drivers/s390/char/con3215.c
@@ -288,12 +288,16 @@ static void raw3215_timeout(unsigned long __data)
 	unsigned long flags;

 	spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
-	if (raw->flags & RAW3215_TIMER_RUNS) {
-		del_timer(&raw->timer);
-		raw->flags &= ~RAW3215_TIMER_RUNS;
-		if (!(raw->port.flags & ASYNC_SUSPENDED)) {
-			raw3215_mk_write_req(raw);
-			raw3215_start_io(raw);
+	raw->flags &= ~RAW3215_TIMER_RUNS;
+	if (!(raw->port.flags & ASYNC_SUSPENDED)) {
+		raw3215_mk_write_req(raw);
+		raw3215_start_io(raw);
+		if ((raw->queued_read || raw->queued_write) &&
+		    !(raw->flags & RAW3215_WORKING) &&
+		    !(raw->flags & RAW3215_TIMER_RUNS)) {
+			raw->timer.expires = RAW3215_TIMEOUT + jiffies;
+			add_timer(&raw->timer);
+			raw->flags |= RAW3215_TIMER_RUNS;
 		}
 	}
 	spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
@@ -317,17 +321,15 @@ static inline void raw3215_try_io(struct raw3215_info *raw)
 		    (raw->flags & RAW3215_FLUSHING)) {
 			/* execute write requests bigger than minimum size */
 			raw3215_start_io(raw);
-			if (raw->flags & RAW3215_TIMER_RUNS) {
-				del_timer(&raw->timer);
-				raw->flags &= ~RAW3215_TIMER_RUNS;
-			}
-		} else if (!(raw->flags & RAW3215_TIMER_RUNS)) {
-			/* delay small writes */
-			raw->timer.expires = RAW3215_TIMEOUT + jiffies;
-			add_timer(&raw->timer);
-			raw->flags |= RAW3215_TIMER_RUNS;
 		}
 	}
+	if ((raw->queued_read || raw->queued_write) &&
+	    !(raw->flags & RAW3215_WORKING) &&
+	    !(raw->flags & RAW3215_TIMER_RUNS)) {
+		raw->timer.expires = RAW3215_TIMEOUT + jiffies;
+		add_timer(&raw->timer);
+		raw->flags |= RAW3215_TIMER_RUNS;
+	}
 }

 /*
--
2.1.4