[PATCH 3.16.y-ckt 004/216] s390/3215: fix hanging console issue

Luis Henriques
2015-01-12T18:05:23Z

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

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@de.ibm.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Luis Henriques <luis.henriques@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