target: Fix early transport_generic_handle_tmr abort scenario

commit c54eeffbe9338fa982dc853d816fda9202a13b5a upstream.

This patch fixes a bug where incoming task management requests
can be explicitly aborted during an active LUN_RESET, but who's
struct work_struct are canceled in-flight before execution.

This occurs when core_tmr_drain_tmr_list() invokes cancel_work_sync()
for the incoming se_tmr_req->task_cmd->work, resulting in cmd->work
for target_tmr_work() never getting invoked and the aborted TMR
waiting indefinately within transport_wait_for_tasks().

To address this case, perform a CMD_T_ABORTED check early in
transport_generic_handle_tmr(), and invoke the normal path via
transport_cmd_check_stop_to_fabric() to complete any TMR kthreads
blocked waiting for CMD_T_STOP in transport_wait_for_tasks().

Also, move the TRANSPORT_ISTATE_PROCESSING assignment earlier
into transport_generic_handle_tmr() so the existing check in
core_tmr_drain_tmr_list() avoids attempting abort the incoming
se_tmr_req->task_cmd->work if it has already been queued into
se_device->tmr_wq.

Reported-by: Rob Millner <rlm@daterainc.com>
Tested-by: Rob Millner <rlm@daterainc.com>
Cc: Rob Millner <rlm@daterainc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
[bwh: Backported to 3.16:
 - Tags are 32-bit; print them with %u
 - Command tag must be looked up with get_task_tag op]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index d3f65523a19d5c12c159c54e62f0914684f7bab1..589f9df574f28eb6137f5288bc697b0f6c15f66d 100644 (file)
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -3093,7 +3093,6 @@ static void target_tmr_work(struct work_struct *work)
                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                goto check_stop;
        }
-       cmd->t_state = TRANSPORT_ISTATE_PROCESSING;
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);
 
        cmd->se_tfo->queue_tm_rsp(cmd);
@@ -3106,11 +3105,25 @@ int transport_generic_handle_tmr(
        struct se_cmd *cmd)
 {
        unsigned long flags;
+       bool aborted = false;
 
        spin_lock_irqsave(&cmd->t_state_lock, flags);
-       cmd->transport_state |= CMD_T_ACTIVE;
+       if (cmd->transport_state & CMD_T_ABORTED) {
+               aborted = true;
+       } else {
+               cmd->t_state = TRANSPORT_ISTATE_PROCESSING;
+               cmd->transport_state |= CMD_T_ACTIVE;
+       }
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);
 
+       if (aborted) {
+               pr_warn_ratelimited("handle_tmr caught CMD_T_ABORTED TMR %d"
+                       "ref_tag: %u tag: %u\n", cmd->se_tmr_req->function,
+                       cmd->se_tmr_req->ref_task_tag, cmd->se_tfo->get_task_tag(cmd));
+               transport_cmd_check_stop_to_fabric(cmd);
+               return 0;
+       }
+
        INIT_WORK(&cmd->work, target_tmr_work);
        queue_work(cmd->se_dev->tmr_wq, &cmd->work);
        return 0;