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[SCSI] ibmvscsi: allow for dynamic adjustment of server request_limit

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The request limit calculations used previously on the client failed to
mirror the state of the server.  Additionally, when a value < 3 was provided
there could be problems setting can_queue and handling abort and reset
commands.

Signed-off-by: "Robert Jennings" <rcj@linux.vnet.ibm.com>
Signed-off-by: Santiago Leon <santil@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This commit is contained in:
Robert Jennings 2007-03-28 12:45:46 -05:00 committed by James Bottomley
parent a45c863f02
commit a897ff2a63
2 changed files with 40 additions and 20 deletions
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58
drivers/scsi/ibmvscsi/ibmvscsi.c
View file

@ -85,7 +85,7 @@
static int max_id = 64;
static int max_channel = 3;
static int init_timeout = 5;
static int max_requests = 50;
static int max_requests = IBMVSCSI_MAX_REQUESTS_DEFAULT;
#define IBMVSCSI_VERSION "1.5.8"
@ -538,7 +538,8 @@ static int ibmvscsi_send_srp_event(struct srp_event_struct *evt_struct,
int request_status;
int rc;
/* If we have exhausted our request limit, just fail this request.
/* If we have exhausted our request limit, just fail this request,
* unless it is for a reset or abort.
* Note that there are rare cases involving driver generated requests
* (such as task management requests) that the mid layer may think we
* can handle more requests (can_queue) when we actually can't
@ -551,9 +552,30 @@ static int ibmvscsi_send_srp_event(struct srp_event_struct *evt_struct,
*/
if (request_status < -1)
goto send_error;
/* Otherwise, if we have run out of requests */
else if (request_status < 0)
goto send_busy;
/* Otherwise, we may have run out of requests. */
/* Abort and reset calls should make it through.
* Nothing except abort and reset should use the last two
* slots unless we had two or less to begin with.
*/
else if (request_status < 2 &&
evt_struct->iu.srp.cmd.opcode != SRP_TSK_MGMT) {
/* In the case that we have less than two requests
* available, check the server limit as a combination
* of the request limit and the number of requests
* in-flight (the size of the send list). If the
* server limit is greater than 2, return busy so
* that the last two are reserved for reset and abort.
*/
int server_limit = request_status;
struct srp_event_struct *tmp_evt;
list_for_each_entry(tmp_evt, &hostdata->sent, list) {
server_limit++;
}
if (server_limit > 2)
goto send_busy;
}
}
/* Copy the IU into the transfer area */
@ -572,6 +594,7 @@ static int ibmvscsi_send_srp_event(struct srp_event_struct *evt_struct,
printk(KERN_ERR "ibmvscsi: send error %d\n",
rc);
atomic_inc(&hostdata->request_limit);
goto send_error;
}
@ -581,7 +604,8 @@ static int ibmvscsi_send_srp_event(struct srp_event_struct *evt_struct,
unmap_cmd_data(&evt_struct->iu.srp.cmd, evt_struct, hostdata->dev);
free_event_struct(&hostdata->pool, evt_struct);
return SCSI_MLQUEUE_HOST_BUSY;
atomic_inc(&hostdata->request_limit);
return SCSI_MLQUEUE_HOST_BUSY;
send_error:
unmap_cmd_data(&evt_struct->iu.srp.cmd, evt_struct, hostdata->dev);
@ -831,23 +855,16 @@ static void login_rsp(struct srp_event_struct *evt_struct)
printk(KERN_INFO "ibmvscsi: SRP_LOGIN succeeded\n");
if (evt_struct->xfer_iu->srp.login_rsp.req_lim_delta >
(max_requests - 2))
evt_struct->xfer_iu->srp.login_rsp.req_lim_delta =
max_requests - 2;
if (evt_struct->xfer_iu->srp.login_rsp.req_lim_delta < 0)
printk(KERN_ERR "ibmvscsi: Invalid request_limit.\n");
/* Now we know what the real request-limit is */
/* Now we know what the real request-limit is.
* This value is set rather than added to request_limit because
* request_limit could have been set to -1 by this client.
*/
atomic_set(&hostdata->request_limit,
evt_struct->xfer_iu->srp.login_rsp.req_lim_delta);
hostdata->host->can_queue =
evt_struct->xfer_iu->srp.login_rsp.req_lim_delta - 2;
if (hostdata->host->can_queue < 1) {
printk(KERN_ERR "ibmvscsi: Invalid request_limit_delta\n");
return;
}
/* If we had any pending I/Os, kick them */
scsi_unblock_requests(hostdata->host);
@ -1483,7 +1500,7 @@ static struct scsi_host_template driver_template = {
.eh_abort_handler = ibmvscsi_eh_abort_handler,
.eh_device_reset_handler = ibmvscsi_eh_device_reset_handler,
.cmd_per_lun = 16,
.can_queue = 1, /* Updated after SRP_LOGIN */
.can_queue = IBMVSCSI_MAX_REQUESTS_DEFAULT,
.this_id = -1,
.sg_tablesize = SG_ALL,
.use_clustering = ENABLE_CLUSTERING,
@ -1503,6 +1520,7 @@ static int ibmvscsi_probe(struct vio_dev *vdev, const struct vio_device_id *id)
vdev->dev.driver_data = NULL;
driver_template.can_queue = max_requests;
host = scsi_host_alloc(&driver_template, sizeof(*hostdata));
if (!host) {
printk(KERN_ERR "ibmvscsi: couldn't allocate host data\n");

2
drivers/scsi/ibmvscsi/ibmvscsi.h
View file

@ -44,6 +44,8 @@ struct Scsi_Host;
*/
#define MAX_INDIRECT_BUFS 10
#define IBMVSCSI_MAX_REQUESTS_DEFAULT 100
/* ------------------------------------------------------------
* Data Structures
*/