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target/tcm_loop: Make TMF processing slightly faster 

Target drivers must guarantee that struct se_cmd and struct se_tmr_req
exist as long as target_tmr_work() is in progress. This is why the
tcm_loop driver today passes 1 as second argument to
transport_generic_free_cmd() from inside the TMF code. Instead of
making the TMF code wait, make the TMF code obtain two references
(SCF_ACK_KREF) and drop one reference from inside the .check_stop_free()
callback.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: David Disseldorp <ddiss@suse.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Bart Van Assche 2017-05-23 16:48:42 -07:00 committed by Nicholas Bellinger
parent 75f141aaf4
commit 4c1f0e6539
1 changed files with 9 additions and 16 deletions
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25
drivers/target/loopback/tcm_loop.c
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@ -51,19 +51,7 @@ static int tcm_loop_queue_status(struct se_cmd *se_cmd);
*/
static int tcm_loop_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 tcm_loop_device_reset()
* with transport_generic_free_cmd().
*/
if (se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)
return 0;
/*
* Release the struct se_cmd, which will make a callback to release
* struct tcm_loop_cmd * in tcm_loop_deallocate_core_cmd()
*/
transport_generic_free_cmd(se_cmd, 0);
return 1;
return transport_generic_free_cmd(se_cmd, 0);
}
static void tcm_loop_release_cmd(struct se_cmd *se_cmd)
@ -244,18 +232,23 @@ static int tcm_loop_issue_tmr(struct tcm_loop_tpg *tl_tpg,
se_sess = tl_tpg->tl_nexus->se_sess;
rc = target_submit_tmr(se_cmd, se_sess, tl_cmd->tl_sense_buf, lun,
NULL, tmr, GFP_KERNEL, task, 0 /*flags*/);
NULL, tmr, GFP_KERNEL, task,
TARGET_SCF_ACK_KREF);
if (rc < 0)
goto release;
wait_for_completion(&tl_cmd->tmr_done);
ret = se_cmd->se_tmr_req->response;
target_put_sess_cmd(se_cmd);
out:
return ret;
release:
if (se_cmd)
transport_generic_free_cmd(se_cmd, 1);
transport_generic_free_cmd(se_cmd, 0);
else
kmem_cache_free(tcm_loop_cmd_cache, tl_cmd);
return ret;
goto out;
}
static int tcm_loop_abort_task(struct scsi_cmnd *sc)