Re: [PATCH-v2 12/12] xen-scsiback: Convert to TARGET_SCF_ACK_KREF I/O krefs

[Juergen Gross <jgross@suse.com>]

On 25/01/16 09:11, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> 
> Cc: Juergen Gross <jgross@suse.com>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: David Vrabel <david.vrabel@citrix.com>
> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
> ---
>  drivers/xen/xen-scsiback.c | 53 +++++++++++++++++++++++-----------------------
>  1 file changed, 26 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
> index 640fb22..a10e5f1 100644
> --- a/drivers/xen/xen-scsiback.c
> +++ b/drivers/xen/xen-scsiback.c
> @@ -381,6 +381,12 @@ static void scsiback_cmd_done(struct vscsibk_pend *pending_req)
>  	scsiback_do_resp_with_sense(sense_buffer, errors, resid, pending_req,
>  				    pending_req->rqid);
>  	scsiback_put(info);
> +	/*
> +	 * Drop the extra KREF_ACK reference taken by target_submit_cmd_map_sgls()
> +	 * ahead of scsiback_check_stop_free() ->  transport_generic_free_cmd()
> +	 * final se_cmd->cmd_kref put.
> +	 */
> +	target_put_sess_cmd(&pending_req->se_cmd);
>  }
>  
>  static void scsiback_cmd_exec(struct vscsibk_pend *pending_req)
> @@ -398,7 +404,7 @@ static void scsiback_cmd_exec(struct vscsibk_pend *pending_req)
>  	rc = target_submit_cmd_map_sgls(se_cmd, sess, pending_req->cmnd,
>  			pending_req->sense_buffer, pending_req->v2p->lun,
>  			pending_req->data_len, 0,
> -			pending_req->sc_data_direction, 0,
> +			pending_req->sc_data_direction, TARGET_SCF_ACK_KREF,
>  			pending_req->sgl, pending_req->n_sg,
>  			NULL, 0, NULL, 0);
>  	if (rc < 0) {
> @@ -587,31 +593,28 @@ static void scsiback_disconnect(struct vscsibk_info *info)
>  static void scsiback_device_action(struct vscsibk_pend *pending_req,
>  	enum tcm_tmreq_table act, int tag)
>  {
> -	int rc, err = FAILED;
>  	struct scsiback_tpg *tpg = pending_req->v2p->tpg;
> +	struct scsiback_nexus *nexus = tpg->tpg_nexus;
>  	struct se_cmd *se_cmd = &pending_req->se_cmd;
>  	struct scsiback_tmr *tmr;
> +	u64 unpacked_lun = pending_req->v2p->lun;
> +	int rc, err = FAILED;
>  
>  	tmr = kzalloc(sizeof(struct scsiback_tmr), GFP_KERNEL);
> -	if (!tmr)
> -		goto out;
> +	if (!tmr) {
> +		target_put_sess_cmd(se_cmd);
> +		goto err;

Sure? I think this should still be "goto out;"?

> +	}
>  
>  	init_waitqueue_head(&tmr->tmr_wait);
>  
> -	transport_init_se_cmd(se_cmd, tpg->se_tpg.se_tpg_tfo,
> -		tpg->tpg_nexus->tvn_se_sess, 0, DMA_NONE, TCM_SIMPLE_TAG,
> -		&pending_req->sense_buffer[0]);
> -
> -	rc = core_tmr_alloc_req(se_cmd, tmr, act, GFP_KERNEL);
> -	if (rc < 0)
> -		goto out;
> -
> -	se_cmd->se_tmr_req->ref_task_tag = tag;
> +	rc = target_submit_tmr(&pending_req->se_cmd, nexus->tvn_se_sess,
> +			       &pending_req->sense_buffer[0],
> +			       unpacked_lun, tmr, act, GFP_KERNEL,
> +			       tag, TARGET_SCF_ACK_KREF);
> +	if (rc)
> +		goto err;

Again.


Juergen

>  
> -	if (transport_lookup_tmr_lun(se_cmd, pending_req->v2p->lun) < 0)
> -		goto out;
> -
> -	transport_generic_handle_tmr(se_cmd);
>  	wait_event(tmr->tmr_wait, atomic_read(&tmr->tmr_complete));
>  
>  	err = (se_cmd->se_tmr_req->response == TMR_FUNCTION_COMPLETE) ?
> @@ -1368,16 +1371,7 @@ static u32 scsiback_tpg_get_inst_index(struct se_portal_group *se_tpg)
>  
>  static int scsiback_check_stop_free(struct se_cmd *se_cmd)
>  {
> -	/*
> -	 * Do not release struct se_cmd's containing a valid TMR pointer.
> -	 * These will be released directly in scsiback_device_action()
> -	 * with transport_generic_free_cmd().
> -	 */
> -	if (se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)
> -		return 0;
> -
> -	transport_generic_free_cmd(se_cmd, 0);
> -	return 1;
> +	return transport_generic_free_cmd(se_cmd, 0);
>  }
>  
>  static void scsiback_release_cmd(struct se_cmd *se_cmd)
> @@ -1385,6 +1379,11 @@ static void scsiback_release_cmd(struct se_cmd *se_cmd)
>  	struct se_session *se_sess = se_cmd->se_sess;
>  	struct se_tmr_req *se_tmr = se_cmd->se_tmr_req;
>  
> +	if (se_tmr && se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB) {
> +		struct scsiback_tmr *tmr = se_tmr->fabric_tmr_ptr;
> +		kfree(tmr);
> +	}
> +
>  	percpu_ida_free(&se_sess->sess_tag_pool, se_cmd->map_tag);
>  }
>  
>