On Wed, Jan 11, 2023 at 09:08:30PM -0600, Mike Christie wrote:
>
> iscsit will set CMD_T_FABRIC_STOP on running commands when its transport
> connection is down and it can't send/recv IO (tx/rx threads are killed
> or the cleanup thread is run from the one thats up). It will then loop
> over running commands and wait for LIO core to complete them or clean
> them up if they were on an internal queue waiting to be sent or ackd.
>
> Currently, CMD_T_FABRIC_STOP only stops TMRs from operating on the
> command but for isert we need to prevent LIO core from calling into
> iscsit callouts when the connection is being brought down. If LIO core
> queues commands to iscsit and it ends up adding to an internal queue
> instead of passing back to the driver then we can end up hanging waiting
> on command completion that never occurs because it's stuck on the internal
> list (the tx thread is stopped at this time, so it will never loop over
> the response list and call into isert). We also want to sync up on a
> point where we no longer call into isert so it can cleanup it's structs.
>
> This has LIO core treat CMD_T_FABRIC_STOP like CMD_T_STOP during
> command execution and also fixes the locking around the
> target_cmd_interrupted calls so we don't have a case where a command
> is marked CMD_T_COMPLETE and CMD_T_STOP|CMD_T_FABRIC_STOP at the same
> time.
>
> Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
> ---
> drivers/target/target_core_sbc.c | 2 +-
> drivers/target/target_core_transport.c | 27 +++++++++++++++-----------
> 2 files changed, 17 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
> index 7536ca797606..56136613767f 100644
> --- a/drivers/target/target_core_sbc.c
> +++ b/drivers/target/target_core_sbc.c
> @@ -459,7 +459,7 @@ static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool succes
> * we don't have to perform the write operation.
> */
> WARN_ON(!(cmd->transport_state &
> - (CMD_T_ABORTED | CMD_T_STOP)));
> + (CMD_T_ABORTED | CMD_T_STOP | CMD_T_FABRIC_STOP)));
> goto out;
> }
> /*
> diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
> index cb3fdc81ba3b..02a9476945dc 100644
> --- a/drivers/target/target_core_transport.c
> +++ b/drivers/target/target_core_transport.c
> @@ -737,8 +737,8 @@ static int transport_cmd_check_stop_to_fabric(struct se_cmd *cmd)
> * Determine if frontend context caller is requesting the stopping of
> * this command for frontend exceptions.
> */
> - if (cmd->transport_state & CMD_T_STOP) {
> - pr_debug("%s:%d CMD_T_STOP for ITT: 0x%08llx\n",
> + if (cmd->transport_state & (CMD_T_STOP | CMD_T_FABRIC_STOP)) {
> + pr_debug("%s:%d CMD_T_STOP|CMD_T_FABRIC_STOP for ITT: 0x%08llx\n",
> __func__, __LINE__, cmd->tag);
>
> spin_unlock_irqrestore(&cmd->t_state_lock, flags);
> @@ -889,7 +889,7 @@ static bool target_cmd_interrupted(struct se_cmd *cmd)
> INIT_WORK(&cmd->work, target_abort_work);
> queue_work(target_completion_wq, &cmd->work);
> return true;
> - } else if (cmd->transport_state & CMD_T_STOP) {
> + } else if (cmd->transport_state & (CMD_T_STOP | CMD_T_FABRIC_STOP)) {
> if (cmd->transport_complete_callback)
> cmd->transport_complete_callback(cmd, false, &post_ret);
> complete_all(&cmd->t_transport_stop_comp);
> @@ -907,13 +907,15 @@ void target_complete_cmd_with_sense(struct se_cmd *cmd, u8 scsi_status,
> int success, cpu;
> unsigned long flags;
>
> - if (target_cmd_interrupted(cmd))
> + spin_lock_irqsave(&cmd->t_state_lock, flags);
That leads to a hardlock because
target_cmd_interrupted() => cmd->transport_complete_callback() also tooks
cmd->t_state_lock.
> + if (target_cmd_interrupted(cmd)) {
> + spin_unlock_irqrestore(&cmd->t_state_lock, flags);
> return;
> + }
>
> cmd->scsi_status = scsi_status;
> cmd->sense_reason = sense_reason;
>
> - spin_lock_irqsave(&cmd->t_state_lock, flags);
> switch (cmd->scsi_status) {
> case SAM_STAT_CHECK_CONDITION:
> if (cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE)
> @@ -2277,10 +2279,12 @@ void target_execute_cmd(struct se_cmd *cmd)
> *
> * If the received CDB has already been aborted stop processing it here.
> */
> - if (target_cmd_interrupted(cmd))
> + spin_lock_irq(&cmd->t_state_lock);
> + if (target_cmd_interrupted(cmd)) {
> + spin_unlock_irq(&cmd->t_state_lock);
> return;
> + }
>
> - spin_lock_irq(&cmd->t_state_lock);
> cmd->t_state = TRANSPORT_PROCESSING;
> cmd->transport_state |= CMD_T_ACTIVE | CMD_T_SENT;
> spin_unlock_irq(&cmd->t_state_lock);
> @@ -2847,9 +2851,9 @@ transport_generic_new_cmd(struct se_cmd *cmd)
> * Determine if frontend context caller is requesting the stopping of
> * this command for frontend exceptions.
> */
> - if (cmd->transport_state & CMD_T_STOP &&
> + if (cmd->transport_state & (CMD_T_STOP | CMD_T_FABRIC_STOP) &&
> !cmd->se_tfo->write_pending_must_be_called) {
> - pr_debug("%s:%d CMD_T_STOP for ITT: 0x%08llx\n",
> + pr_debug("%s:%d CMD_T_STOP|CMD_T_FABRIC_STOPfor ITT: 0x%08llx\n",
> __func__, __LINE__, cmd->tag);
>
> spin_unlock_irqrestore(&cmd->t_state_lock, flags);
> @@ -2880,11 +2884,12 @@ static void transport_write_pending_qf(struct se_cmd *cmd)
> bool stop;
>
> spin_lock_irqsave(&cmd->t_state_lock, flags);
> - stop = (cmd->transport_state & (CMD_T_STOP | CMD_T_ABORTED));
> + stop = (cmd->transport_state &
> + (CMD_T_STOP | CMD_T_FABRIC_STOP | CMD_T_ABORTED));
> spin_unlock_irqrestore(&cmd->t_state_lock, flags);
>
> if (stop) {
> - pr_debug("%s:%d CMD_T_STOP|CMD_T_ABORTED for ITT: 0x%08llx\n",
> + pr_debug("%s:%d CMD_T_STOP|CMD_T_FABRIC_STOP|CMD_T_ABORTED for ITT: 0x%08llx\n",
> __func__, __LINE__, cmd->tag);
> complete_all(&cmd->t_transport_stop_comp);
> return;
> --
> 2.31.1
>
>
