[SCSI] ibmvscsi: allow for dynamic adjustment of server request_limit
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>
diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index fbc1d5c..383f594 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -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 @@
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 @@
*/
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 @@
printk(KERN_ERR "ibmvscsi: send error %d\n",
rc);
+ atomic_inc(&hostdata->request_limit);
goto send_error;
}
@@ -581,7 +604,8 @@
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 @@
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 @@
.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 @@
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");