From 56e25e9777bf15365293e27a3256eb9214a11edf Mon Sep 17 00:00:00 2001 From: Peter Oberparleiter Date: Thu, 26 Mar 2009 15:24:20 +0100 Subject: [PATCH] [S390] cio: prevent workqueue deadlock Subchannel reprobing can block the kslowcrw workqueue indefinitely while waiting for device recognition to finish which is also scheduled to run on kslowcrw. Prevent this deadlock by moving the waiting portion of subchannel reprobing to the cio workqueue. Signed-off-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky --- drivers/s390/cio/css.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c index 1f2e424..8446d15 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -533,6 +533,17 @@ static int reprobe_subchannel(struct subchannel_id schid, void *data) return ret; } +static void reprobe_after_idle(struct work_struct *unused) +{ + /* Make sure initial subchannel scan is done. */ + wait_event(ccw_device_init_wq, + atomic_read(&ccw_device_init_count) == 0); + if (need_reprobe) + css_schedule_reprobe(); +} + +static DECLARE_WORK(reprobe_idle_work, reprobe_after_idle); + /* Work function used to reprobe all unregistered subchannels. */ static void reprobe_all(struct work_struct *unused) { @@ -540,10 +551,12 @@ static void reprobe_all(struct work_struct *unused) CIO_MSG_EVENT(4, "reprobe start\n"); - need_reprobe = 0; /* Make sure initial subchannel scan is done. */ - wait_event(ccw_device_init_wq, - atomic_read(&ccw_device_init_count) == 0); + if (atomic_read(&ccw_device_init_count) != 0) { + queue_work(ccw_device_work, &reprobe_idle_work); + return; + } + need_reprobe = 0; ret = for_each_subchannel_staged(NULL, reprobe_subchannel, NULL); CIO_MSG_EVENT(4, "reprobe done (rc=%d, need_reprobe=%d)\n", ret, -- 2.7.4