diff options
| author | Mike Christie <michael.christie@oracle.com> | 2022-06-16 17:45:54 -0500 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2022-06-21 21:19:23 -0400 |
| commit | 533ac412fdb4cbc8ce282b1ee1991e03b2717625 (patch) | |
| tree | 0d72867dcbd9fa78f5b3cd95c2304fc6700e849e /drivers/scsi/libiscsi.c | |
| parent | 9b89153680f65ba5d9229e8082a9eeed7adbd360 (diff) | |
scsi: iscsi: Remove unneeded task state check
Commit 5923d64b7ab6 ("scsi: libiscsi: Drop taskqueuelock") added an extra
task->state because for commit 6f8830f5bbab ("scsi: libiscsi: add lock
around task lists to fix list corruption regression") we didn't know why we
ended up with cmds on the list and thought it might have been a bad target
sending a response while we were still sending the cmd. We were never able
to get a target to send us a response early, because it turns out the bug
was just a race in libiscsi/libiscsi_tcp where:
1. iscsi_tcp_r2t_rsp() queues a r2t to tcp_task->r2tqueue.
2. iscsi_tcp_task_xmit() runs iscsi_tcp_get_curr_r2t() and sees we have a
r2t. It dequeues it and iscsi_tcp_task_xmit() starts to process it.
3. iscsi_tcp_r2t_rsp() runs iscsi_requeue_task() and puts the task on the
requeue list.
4. iscsi_tcp_task_xmit() sends the data for r2t. This is the final chunk
of data, so the cmd is done.
5. target sends the response.
6. On a different CPU from #3, iscsi_complete_task() processes the
response. Since there was no common lock for the list, the lists/tasks
pointers are not fully in sync, so could end up with list corruption.
Since it was just a race on our side, remove the extra check and fix up the
comments.
Link: https://lore.kernel.org/r/20220616224557.115234-7-michael.christie@oracle.com
Reviewed-by: Wu Bo <wubo40@huawei.com>
Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/libiscsi.c')
| -rw-r--r-- | drivers/scsi/libiscsi.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c index 20156fb33646..fce9f9e5b00b 100644 --- a/drivers/scsi/libiscsi.c +++ b/drivers/scsi/libiscsi.c @@ -567,16 +567,19 @@ static bool cleanup_queued_task(struct iscsi_task *task) struct iscsi_conn *conn = task->conn; bool early_complete = false; - /* Bad target might have completed task while it was still running */ + /* + * We might have raced where we handled a R2T early and got a response + * but have not yet taken the task off the requeue list, then a TMF or + * recovery happened and so we can still see it here. + */ if (task->state == ISCSI_TASK_COMPLETED) early_complete = true; if (!list_empty(&task->running)) { list_del_init(&task->running); /* - * If it's on a list but still running, this could be from - * a bad target sending a rsp early, cleanup from a TMF, or - * session recovery. + * If it's on a list but still running this could be cleanup + * from a TMF or session recovery. */ if (task->state == ISCSI_TASK_RUNNING || task->state == ISCSI_TASK_COMPLETED) @@ -1485,7 +1488,7 @@ static int iscsi_xmit_task(struct iscsi_conn *conn, struct iscsi_task *task, } /* regular RX path uses back_lock */ spin_lock(&conn->session->back_lock); - if (rc && task->state == ISCSI_TASK_RUNNING) { + if (rc) { /* * get an extra ref that is released next time we access it * as conn->task above. |