The race condition can be observed with the following sequence of events:
- For every active sessions, issue an ISCSI_ERR_CONN_FAILED nl msg
(This will eventually put all active connections into the actor_list ready
to execute the session_conn_reopen procedure)
- Asynchronously after a few seconds, call the iscsi_host_remove procedure
(This will notify iscsid with the ISCSI_ERR_INVALID_HOST nl message)
The current code actually handles this by advancing the INVALID_HOST
session_conn_error actor scheduing to the head via the actor_schedule_head
procedure. However, if the current actor thread was call-backed from the
actor_poll loop, then this head scheduling will actually put the INVALID_HOST
actor onto the poll_list instead of the actor_list.
If there are subsequent elements in the actor_list which triggers the reopen
path, then the conn_context for the INVALID_HOST for that particular
connection will get flushed (+ actor_delete). This will then lockup the
libiscsi's iscsi_host_remove call as it will wait indefinitely on all
sessions to be removed.
The fix is to put this head scheduling to the head of the actor_list
regardless of poll mode or not. This will allow all INVALID_PATH actors
to have a chance to get executed before any subsequent reopen actors.
Signed-off-by: Eddie Wai <eddie....@broadcom.com>
---
usr/actor.c | 13 ++++++-------
1 files changed, 6 insertions(+), 7 deletions(-)
diff --git a/usr/actor.c b/usr/actor.c
index e88d197..45f3a51 100644
--- a/usr/actor.c
+++ b/usr/actor.c
@@ -112,14 +112,13 @@ actor_schedule_private(actor_t *thread, uint32_t
ttschedule, int head)
* state to scheduled, else add current time to ttschedule and
* insert in the queue at the correct point */
if (delay_time == 0) {
- if (poll_in_progress) {
+ /* For head addition, it must go onto the head of the
+ actor_list regardless if poll is in progress or not
+ */
+ if (poll_in_progress && !head) {
thread->state = ACTOR_POLL_WAITING;
- if (head)
- list_add(&thread->list,
- &poll_list);
- else
- list_add_tail(&thread->list,
- &poll_list);
+ list_add_tail(&thread->list,
+ &poll_list);
} else {
thread->state = ACTOR_SCHEDULED;
if (head)
--
1.7.0.5
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