Vivek Goyal 51fecdd255 virtiofs: Do not end request in submission context
Submission context can hold some locks which end request code tries to hold
again and deadlock can occur. For example, fc->bg_lock. If a background
request is being submitted, it might hold fc->bg_lock and if we could not
submit request (because device went away) and tried to end request, then
deadlock happens. During testing, I also got a warning from deadlock
detection code.

So put requests on a list and end requests from a worker thread.

I got following warning from deadlock detector.

[  603.137138] WARNING: possible recursive locking detected
[  603.137142] --------------------------------------------
[  603.137144] blogbench/2036 is trying to acquire lock:
[  603.137149] 00000000f0f51107 (&(&fc->bg_lock)->rlock){+.+.}, at: fuse_request_end+0xdf/0x1c0 [fuse]
[  603.140701]
[  603.140701] but task is already holding lock:
[  603.140703] 00000000f0f51107 (&(&fc->bg_lock)->rlock){+.+.}, at: fuse_simple_background+0x92/0x1d0 [fuse]
[  603.140713]
[  603.140713] other info that might help us debug this:
[  603.140714]  Possible unsafe locking scenario:
[  603.140714]
[  603.140715]        CPU0
[  603.140716]        ----
[  603.140716]   lock(&(&fc->bg_lock)->rlock);
[  603.140718]   lock(&(&fc->bg_lock)->rlock);
[  603.140719]
[  603.140719]  *** DEADLOCK ***

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2019-10-21 15:57:07 +02:00
..
2019-09-27 15:10:34 -07:00
2019-09-30 10:25:24 -07:00
2019-09-25 10:21:13 -07:00
2019-09-19 09:42:37 -07:00
2019-09-19 13:09:28 -07:00
2019-07-12 17:37:53 -07:00
\n
2019-09-21 13:53:34 -07:00
2019-09-29 19:25:39 -07:00
2019-09-21 14:26:33 -07:00
2019-09-19 09:42:37 -07:00
2019-09-19 09:42:37 -07:00
2019-07-03 17:52:09 -04:00
2019-09-26 12:20:14 -07:00
2019-09-27 17:00:27 -07:00
2019-09-27 17:00:27 -07:00
2019-09-19 10:21:35 -07:00
2019-08-30 08:11:25 -07:00
2019-09-19 09:42:37 -07:00
2019-09-26 11:36:20 -07:00
2019-09-18 17:35:20 -07:00
2019-07-15 21:20:52 -07:00
2019-04-08 18:21:02 -05:00
2019-08-07 21:51:47 -04:00
2019-03-08 14:48:40 -08:00
2019-09-27 12:08:24 -07:00
2019-09-18 16:59:14 -07:00
2019-09-27 17:00:27 -07:00
2019-09-18 16:59:14 -07:00
2019-02-07 16:38:35 +01:00
2019-09-25 09:55:59 -07:00
2019-08-01 20:51:23 +02:00
2019-09-25 17:51:41 -07:00