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tcm_loop: defer all command submissions to workqueue 

Apply the qla2xxx model of submitting all commands from a workqueue.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Christoph Hellwig 2012-02-02 17:04:41 -05:00 committed by Nicholas Bellinger
parent f872c9f417
commit afe2cb7fb1
2 changed files with 58 additions and 41 deletions
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97
drivers/target/loopback/tcm_loop.c
View File

@ -44,6 +44,7 @@
/* Local pointer to allocated TCM configfs fabric module */
static struct target_fabric_configfs *tcm_loop_fabric_configfs;
static struct workqueue_struct *tcm_loop_workqueue;
static struct kmem_cache *tcm_loop_cmd_cache;
static int tcm_loop_hba_no_cnt;
@ -206,32 +207,19 @@ static int tcm_loop_sam_attr(struct scsi_cmnd *sc)
return MSG_SIMPLE_TAG;
}
/*
* Main entry point from struct scsi_host_template for incoming SCSI CDB+Data
* from Linux/SCSI subsystem for SCSI low level device drivers (LLDs)
*/
static int tcm_loop_queuecommand(
struct Scsi_Host *sh,
struct scsi_cmnd *sc)
static void tcm_loop_submission_work(struct work_struct *work)
{
struct se_cmd *se_cmd;
struct se_portal_group *se_tpg;
struct tcm_loop_cmd *tl_cmd =
container_of(work, struct tcm_loop_cmd, work);
struct se_cmd *se_cmd = &tl_cmd->tl_se_cmd;
struct scsi_cmnd *sc = tl_cmd->sc;
struct tcm_loop_nexus *tl_nexus;
struct tcm_loop_hba *tl_hba;
struct tcm_loop_tpg *tl_tpg;
struct se_session *se_sess;
struct tcm_loop_nexus *tl_nexus;
struct tcm_loop_cmd *tl_cmd;
pr_debug("tcm_loop_queuecommand() %d:%d:%d:%d got CDB: 0x%02x"
" scsi_buf_len: %u\n", sc->device->host->host_no,
sc->device->id, sc->device->channel, sc->device->lun,
sc->cmnd[0], scsi_bufflen(sc));
/*
* Locate the tcm_loop_hba_t pointer
*/
tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];
/*
* Ensure that this tl_tpg reference from the incoming sc->device->id
* has already been configured via tcm_loop_make_naa_tpg().
@ -240,7 +228,6 @@ static int tcm_loop_queuecommand(
set_host_byte(sc, DID_NO_CONNECT);
goto out_done;
}
se_tpg = &tl_tpg->tl_se_tpg;
tl_nexus = tl_hba->tl_nexus;
if (!tl_nexus) {
@ -249,18 +236,9 @@ static int tcm_loop_queuecommand(
set_host_byte(sc, DID_ERROR);
goto out_done;
}
se_sess = tl_nexus->se_sess;
tl_cmd = kmem_cache_zalloc(tcm_loop_cmd_cache, GFP_ATOMIC);
if (!tl_cmd) {
pr_err("Unable to allocate struct tcm_loop_cmd\n");
set_host_byte(sc, DID_ERROR);
goto out_done;
}
se_cmd = &tl_cmd->tl_se_cmd;
tl_cmd->sc = sc;
transport_init_se_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess,
transport_init_se_cmd(se_cmd, tl_tpg->tl_se_tpg.se_tpg_tfo,
tl_nexus->se_sess,
scsi_bufflen(sc), sc->sc_data_direction,
tcm_loop_sam_attr(sc), &tl_cmd->tl_sense_buf[0]);
@ -274,10 +252,37 @@ static int tcm_loop_queuecommand(
}
transport_generic_handle_cdb_map(se_cmd);
return 0;
return;
out_done:
sc->scsi_done(sc);
return;
}
/*
* ->queuecommand can be and usually is called from interrupt context, so
* defer the actual submission to a workqueue.
*/
static int tcm_loop_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc)
{
struct tcm_loop_cmd *tl_cmd;
pr_debug("tcm_loop_queuecommand() %d:%d:%d:%d got CDB: 0x%02x"
" scsi_buf_len: %u\n", sc->device->host->host_no,
sc->device->id, sc->device->channel, sc->device->lun,
sc->cmnd[0], scsi_bufflen(sc));
tl_cmd = kmem_cache_zalloc(tcm_loop_cmd_cache, GFP_ATOMIC);
if (!tl_cmd) {
pr_err("Unable to allocate struct tcm_loop_cmd\n");
set_host_byte(sc, DID_ERROR);
sc->scsi_done(sc);
return 0;
}
tl_cmd->sc = sc;
INIT_WORK(&tl_cmd->work, tcm_loop_submission_work);
queue_work(tcm_loop_workqueue, &tl_cmd->work);
return 0;
}
@ -1458,7 +1463,11 @@ static void tcm_loop_deregister_configfs(void)
static int __init tcm_loop_fabric_init(void)
{
int ret;
int ret = -ENOMEM;
tcm_loop_workqueue = alloc_workqueue("tcm_loop", 0, 0);
if (!tcm_loop_workqueue)
goto out;
tcm_loop_cmd_cache = kmem_cache_create("tcm_loop_cmd_cache",
sizeof(struct tcm_loop_cmd),
@ -1467,20 +1476,27 @@ static int __init tcm_loop_fabric_init(void)
if (!tcm_loop_cmd_cache) {
pr_debug("kmem_cache_create() for"
" tcm_loop_cmd_cache failed\n");
return -ENOMEM;
goto out_destroy_workqueue;
}
ret = tcm_loop_alloc_core_bus();
if (ret)
return ret;
goto out_destroy_cache;
ret = tcm_loop_register_configfs();
if (ret) {
tcm_loop_release_core_bus();
return ret;
}
if (ret)
goto out_release_core_bus;
return 0;
out_release_core_bus:
tcm_loop_release_core_bus();
out_destroy_cache:
kmem_cache_destroy(tcm_loop_cmd_cache);
out_destroy_workqueue:
destroy_workqueue(tcm_loop_workqueue);
out:
return ret;
}
static void __exit tcm_loop_fabric_exit(void)
@ -1488,6 +1504,7 @@ static void __exit tcm_loop_fabric_exit(void)
tcm_loop_deregister_configfs();
tcm_loop_release_core_bus();
kmem_cache_destroy(tcm_loop_cmd_cache);
destroy_workqueue(tcm_loop_workqueue);
}
MODULE_DESCRIPTION("TCM loopback virtual Linux/SCSI fabric module");

2
drivers/target/loopback/tcm_loop.h
View File

@ -12,9 +12,9 @@ struct tcm_loop_cmd {
u32 sc_cmd_state;
/* Pointer to the CDB+Data descriptor from Linux/SCSI subsystem */
struct scsi_cmnd *sc;
struct list_head *tl_cmd_list;
/* The TCM I/O descriptor that is accessed via container_of() */
struct se_cmd tl_se_cmd;
struct work_struct work;
/* Sense buffer that will be mapped into outgoing status */
unsigned char tl_sense_buf[TRANSPORT_SENSE_BUFFER];
};