a8fabb3852
In case a user process using xenbus has open transactions and is killed
e.g. via ctrl-C the following cleanup of the allocated resources might
result in a deadlock due to trying to end a transaction in the xenbus
worker thread:
[ 2551.474706] INFO: task xenbus:37 blocked for more than 120 seconds.
[ 2551.492215] Tainted: P OE 5.0.0-29-generic #5
[ 2551.510263] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 2551.528585] xenbus D 0 37 2 0x80000080
[ 2551.528590] Call Trace:
[ 2551.528603] __schedule+0x2c0/0x870
[ 2551.528606] ? _cond_resched+0x19/0x40
[ 2551.528632] schedule+0x2c/0x70
[ 2551.528637] xs_talkv+0x1ec/0x2b0
[ 2551.528642] ? wait_woken+0x80/0x80
[ 2551.528645] xs_single+0x53/0x80
[ 2551.528648] xenbus_transaction_end+0x3b/0x70
[ 2551.528651] xenbus_file_free+0x5a/0x160
[ 2551.528654] xenbus_dev_queue_reply+0xc4/0x220
[ 2551.528657] xenbus_thread+0x7de/0x880
[ 2551.528660] ? wait_woken+0x80/0x80
[ 2551.528665] kthread+0x121/0x140
[ 2551.528667] ? xb_read+0x1d0/0x1d0
[ 2551.528670] ? kthread_park+0x90/0x90
[ 2551.528673] ret_from_fork+0x35/0x40
Fix this by doing the cleanup via a workqueue instead.
Reported-by: James Dingwall <james@dingwall.me.uk>
Fixes:
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||
|---|---|---|
| .. | ||
| Makefile | ||
| xenbus_client.c | ||
| xenbus_comms.c | ||
| xenbus_dev_backend.c | ||
| xenbus_dev_frontend.c | ||
| xenbus_probe_backend.c | ||
| xenbus_probe_frontend.c | ||
| xenbus_probe.c | ||
| xenbus_xs.c | ||
| xenbus.h | ||