[PATCH 5/5] ibmvfc: relax locking around ibmvfc_queuecommand

Tyrel Datwyler
2020-12-18T23:20:48Z

The drivers queuecommand routine is still wrapped to hold the host lock
for the duration of the call. This will become problematic when moving
to multiple queues due to the lock contention preventing asynchronous
submissions to mulitple queues. There is no real legatimate reason to
hold the host lock, and previous patches have insured proper protection
of moving ibmvfc_event objects between free and sent lists.

Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
---
drivers/scsi/ibmvscsi/ibmvfc.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index b74080489807..151e9111ab8a 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -1793,10 +1793,9 @@ static struct ibmvfc_cmd *ibmvfc_init_vfc_cmd(struct ibmvfc_event *evt, struct s
* Returns:
* 0 on success / other on failure
**/
-static int ibmvfc_queuecommand_lck(struct scsi_cmnd *cmnd,
- void (*done) (struct scsi_cmnd *))
+static int ibmvfc_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *cmnd)
{
- struct ibmvfc_host *vhost = shost_priv(cmnd->device->host);
+ struct ibmvfc_host *vhost = shost_priv(shost);
struct fc_rport *rport = starget_to_rport(scsi_target(cmnd->device));
struct ibmvfc_cmd *vfc_cmd;
struct ibmvfc_fcp_cmd_iu *iu;
@@ -1806,7 +1805,7 @@ static int ibmvfc_queuecommand_lck(struct scsi_cmnd *cmnd,
if (unlikely((rc = fc_remote_port_chkready(rport))) ||
unlikely((rc = ibmvfc_host_chkready(vhost)))) {
cmnd->result = rc;
- done(cmnd);
+ cmnd->scsi_done(cmnd);
return 0;
}

@@ -1814,7 +1813,6 @@ static int ibmvfc_queuecommand_lck(struct scsi_cmnd *cmnd,
evt = ibmvfc_get_event(&vhost->crq);
ibmvfc_init_event(evt, ibmvfc_scsi_done, IBMVFC_CMD_FORMAT);
evt->cmnd = cmnd;
- cmnd->scsi_done = done;

vfc_cmd = ibmvfc_init_vfc_cmd(evt, cmnd->device);
iu = ibmvfc_get_fcp_iu(vhost, vfc_cmd);
@@ -1841,12 +1839,10 @@ static int ibmvfc_queuecommand_lck(struct scsi_cmnd *cmnd,
"Failed to map DMA buffer for command. rc=%d\n", rc);

cmnd->result = DID_ERROR << 16;
- done(cmnd);
+ cmnd->scsi_done(cmnd);
return 0;
}

-static DEF_SCSI_QCMD(ibmvfc_queuecommand)
-
/**
* ibmvfc_sync_completion - Signal that a synchronous command has completed
* @evt: ibmvfc event struct
--
2.27.0