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Further lock contention reduction / exported max_host_blocked.

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git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@2347 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2010-10-04 17:05:10 +00:00
parent 92b70d4f83
commit 4009410ce2
1 changed files with 154 additions and 67 deletions
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221
scripts/generate-kernel-with-srp-patches
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@@ -892,10 +892,18 @@ EOF
get_locking_per_lun_patch() {
cat <<EOF
diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index a2935e3..dda5203 100644
index a2935e3..f2cc342 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -441,18 +441,30 @@ static void srp_disconnect_target(struct srp_target_port *target)
@@ -81,6 +81,7 @@ MODULE_PARM_DESC(mellanox_workarounds,
static void srp_add_one(struct ib_device *device);
static void srp_remove_one(struct ib_device *device);
static void srp_recv_completion(struct ib_cq *cq, void *target_ptr);
+static void __srp_send_completion(struct ib_cq *cq, void *target_ptr);
static void srp_send_completion(struct ib_cq *cq, void *target_ptr);
static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event);
@@ -441,18 +442,30 @@ static void srp_disconnect_target(struct srp_target_port *target)
wait_for_completion(&target->done);
}
@@ -932,7 +940,7 @@ index a2935e3..dda5203 100644
spin_lock(&target->srp_host->target_lock);
list_del(&target->list);
@@ -541,8 +553,13 @@ static void srp_unmap_data(struct scsi_cmnd *scmnd,
@@ -541,8 +554,13 @@ static void srp_unmap_data(struct scsi_cmnd *scmnd,
static void srp_remove_req(struct srp_target_port *target, struct srp_request *req)
{
@@ -947,7 +955,7 @@ index a2935e3..dda5203 100644
}
static void srp_reset_req(struct srp_target_port *target, struct srp_request *req)
@@ -555,17 +572,14 @@ static void srp_reset_req(struct srp_target_port *target, struct srp_request *re
@@ -555,17 +573,14 @@ static void srp_reset_req(struct srp_target_port *target, struct srp_request *re
static int srp_reconnect_target(struct srp_target_port *target)
{
struct ib_qp_attr qp_attr;
@@ -968,7 +976,7 @@ index a2935e3..dda5203 100644
srp_disconnect_target(target);
/*
@@ -590,27 +604,20 @@ static int srp_reconnect_target(struct srp_target_port *target)
@@ -590,27 +605,20 @@ static int srp_reconnect_target(struct srp_target_port *target)
while (ib_poll_cq(target->send_cq, 1, &wc) > 0)
; /* nothing */
@@ -1002,7 +1010,7 @@ index a2935e3..dda5203 100644
return ret;
@@ -624,13 +631,11 @@ err:
@@ -624,13 +632,11 @@ err:
* be in the context of the SCSI error handler now, which
* would deadlock if we call scsi_remove_host().
*/
@@ -1018,7 +1026,7 @@ index a2935e3..dda5203 100644
return ret;
}
@@ -811,20 +816,12 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
@@ -811,20 +817,12 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
return len;
}
@@ -1031,9 +1039,9 @@ index a2935e3..dda5203 100644
struct ib_recv_wr wr, *bad_wr;
- unsigned int next;
- int ret;
- spin_lock_irqsave(target->scsi_host->host_lock, flags);
-
- spin_lock_irqsave(target->scsi_host->host_lock, flags);
- next = target->rx_head & SRP_RQ_MASK;
- wr.wr_id = next;
- iu = target->rx_ring[next];
@@ -1041,7 +1049,7 @@ index a2935e3..dda5203 100644
list.addr = iu->dma;
list.length = iu->size;
@@ -834,13 +831,7 @@ static int srp_post_recv(struct srp_target_port *target)
@@ -834,13 +832,7 @@ static int srp_post_recv(struct srp_target_port *target)
wr.sg_list = &list;
wr.num_sge = 1;
@@ -1056,7 +1064,7 @@ index a2935e3..dda5203 100644
}
static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
@@ -852,9 +843,9 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
@@ -852,9 +844,9 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
delta = (s32) be32_to_cpu(rsp->req_lim_delta);
@@ -1068,7 +1076,7 @@ index a2935e3..dda5203 100644
req = &target->req_ring[rsp->tag & ~SRP_TAG_TSK_MGMT];
@@ -892,14 +883,12 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
@@ -892,14 +884,12 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
} else
req->cmd_done = 1;
}
@@ -1086,18 +1094,19 @@ index a2935e3..dda5203 100644
*
* Note:
* An upper limit for the number of allocated information units for each
@@ -914,24 +903,29 @@ static struct srp_iu *__srp_get_tx_iu(struct srp_target_port *target,
@@ -914,24 +904,29 @@ static struct srp_iu *__srp_get_tx_iu(struct srp_target_port *target,
enum srp_tx_iu_type iu_type)
{
s32 rsv = (iu_type == SRP_IU_TSK_MGMT) ? 0 : SRP_TSK_MGMT_SQ_SIZE;
+ struct srp_iu *res = NULL;
+ unsigned long flags;
srp_send_completion(target->send_cq, target);
- srp_send_completion(target->send_cq, target);
+ spin_lock_irqsave(&target->lock, flags);
- if (target->tx_head - target->tx_tail >= SRP_SQ_SIZE)
- return NULL;
+ spin_lock_irqsave(&target->lock, flags);
+ __srp_send_completion(target->send_cq, target);
+
+ if (list_empty(&target->tx_free))
+ goto out;
@@ -1124,7 +1133,7 @@ index a2935e3..dda5203 100644
static int __srp_post_send(struct srp_target_port *target,
struct srp_iu *iu, int len,
enum srp_send_iu_type iu_type)
@@ -945,7 +939,7 @@ static int __srp_post_send(struct srp_target_port *target,
@@ -945,7 +940,7 @@ static int __srp_post_send(struct srp_target_port *target,
list.lkey = target->srp_host->srp_dev->mr->lkey;
wr.next = NULL;
@@ -1133,7 +1142,7 @@ index a2935e3..dda5203 100644
wr.sg_list = &list;
wr.num_sge = 1;
wr.opcode = IB_WR_SEND;
@@ -953,43 +947,45 @@ static int __srp_post_send(struct srp_target_port *target,
@@ -953,43 +948,45 @@ static int __srp_post_send(struct srp_target_port *target,
ret = ib_post_send(target->qp, &wr, &bad_wr);
@@ -1194,7 +1203,7 @@ index a2935e3..dda5203 100644
shost_printk(KERN_ERR, target->scsi_host,
PFX "ignoring AER for LUN %llu\n", be64_to_cpu(req->lun));
@@ -1006,7 +1002,6 @@ static void srp_handle_req(struct srp_target_port *target,
@@ -1006,7 +1003,6 @@ static void srp_handle_req(struct srp_target_port *target,
{
struct ib_device *dev;
u8 *req_buf;
@@ -1202,7 +1211,7 @@ index a2935e3..dda5203 100644
struct srp_iu *rsp_iu;
u8 *rsp_buf;
int res;
@@ -1014,11 +1009,9 @@ static void srp_handle_req(struct srp_target_port *target,
@@ -1014,11 +1010,9 @@ static void srp_handle_req(struct srp_target_port *target,
dev = target->srp_host->srp_dev->dev;
req_buf = req_iu->buf;
@@ -1215,7 +1224,7 @@ index a2935e3..dda5203 100644
rsp_buf = rsp_iu->buf;
@@ -1031,9 +1024,6 @@ static void srp_handle_req(struct srp_target_port *target,
@@ -1031,9 +1025,6 @@ static void srp_handle_req(struct srp_target_port *target,
if (res)
shost_printk(KERN_ERR, target->scsi_host,
PFX "Sending response failed -- res = %d\n", res);
@@ -1225,7 +1234,7 @@ index a2935e3..dda5203 100644
}
static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
@@ -1070,11 +1060,11 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
@@ -1070,11 +1061,11 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
break;
case SRP_CRED_REQ:
@@ -1239,7 +1248,7 @@ index a2935e3..dda5203 100644
break;
default:
@@ -1086,7 +1076,7 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
@@ -1086,7 +1077,7 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
ib_dma_sync_single_for_device(dev, iu->dma, target->max_ti_iu_len,
DMA_FROM_DEVICE);
@@ -1248,12 +1257,12 @@ index a2935e3..dda5203 100644
if (res != 0)
shost_printk(KERN_ERR, target->scsi_host,
PFX "Recv failed with error code %d\n", res);
@@ -1095,38 +1085,53 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
@@ -1095,38 +1086,59 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
static void srp_recv_completion(struct ib_cq *cq, void *target_ptr)
{
struct srp_target_port *target = target_ptr;
- struct ib_wc wc;
+ struct ib_wc wc[4];
+ struct ib_wc *const wc = target->recv_wc;
+ int i, n;
ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
@@ -1265,7 +1274,7 @@ index a2935e3..dda5203 100644
- target->qp_in_error = 1;
- break;
- }
+ while ((n = ib_poll_cq(cq, ARRAY_SIZE(wc), wc)) > 0) {
+ while ((n = ib_poll_cq(cq, ARRAY_SIZE(target->recv_wc), wc)) > 0) {
+ for (i = 0; i < n; ++i) {
+ if (wc[i].status) {
+ shost_printk(KERN_ERR, target->scsi_host,
@@ -1283,13 +1292,23 @@ index a2935e3..dda5203 100644
+ return;
}
static void srp_send_completion(struct ib_cq *cq, void *target_ptr)
-static void srp_send_completion(struct ib_cq *cq, void *target_ptr)
+static void __srp_send_completion(struct ib_cq *cq, void *target_ptr)
{
struct srp_target_port *target = target_ptr;
- struct ib_wc wc;
+ struct ib_wc wc[4];
+ struct ib_wc *const wc = target->send_wc;
+ int i, n;
+ unsigned long flags;
+
+ while ((n = ib_poll_cq(cq, ARRAY_SIZE(target->send_wc), wc)) > 0) {
+ for (i = 0; i < n; ++i) {
+ if (wc[i].status) {
+ shost_printk(KERN_ERR, target->scsi_host,
+ PFX "failed send status %d\n",
+ wc[i].status);
+ target->qp_in_error = 1;
+ goto out;
+ }
- while (ib_poll_cq(cq, 1, &wc) > 0) {
- if (wc.status) {
@@ -1298,31 +1317,28 @@ index a2935e3..dda5203 100644
- wc.status);
- target->qp_in_error = 1;
- break;
- }
+ while ((n = ib_poll_cq(cq, ARRAY_SIZE(wc), wc)) > 0) {
+ spin_lock_irqsave(&target->lock, flags);
+ for (i = 0; i < n; ++i) {
+ if (wc[i].status) {
+ shost_printk(KERN_ERR, target->scsi_host,
+ PFX "failed send status %d\n",
+ wc[i].status);
+ target->qp_in_error = 1;
+ spin_unlock_irqrestore(&target->lock, flags);
+ goto out;
+ }
- ++target->tx_tail;
+ list_add_tail(&target->tx_ring[wc[i].wr_id]->list,
+ &target->tx_free);
+ }
+ spin_unlock_irqrestore(&target->lock, flags);
}
-
- ++target->tx_tail;
}
+out:
+ return;
+}
+
+static void srp_send_completion(struct ib_cq *cq, void *target_ptr)
+{
+ struct srp_target_port *target = target_ptr;
+ unsigned long flags;
+
+ spin_lock_irqsave(&target->lock, flags);
+ __srp_send_completion(cq, target_ptr);
+ spin_unlock_irqrestore(&target->lock, flags);
}
static int srp_queuecommand(struct scsi_cmnd *scmnd,
@@ -1138,6 +1143,7 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
@@ -1138,6 +1150,7 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
struct srp_cmd *cmd;
struct ib_device *dev;
int len;
@@ -1330,7 +1346,7 @@ index a2935e3..dda5203 100644
if (target->state == SRP_TARGET_CONNECTING)
goto err;
@@ -1157,7 +1163,10 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
@@ -1157,7 +1170,10 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
ib_dma_sync_single_for_cpu(dev, iu->dma, srp_max_iu_len,
DMA_TO_DEVICE);
@@ -1341,7 +1357,7 @@ index a2935e3..dda5203 100644
scmnd->scsi_done = done;
scmnd->result = 0;
@@ -1180,7 +1189,7 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
@@ -1180,7 +1196,7 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
if (len < 0) {
shost_printk(KERN_ERR, target->scsi_host,
PFX "Failed to map data\n");
@@ -1350,7 +1366,7 @@ index a2935e3..dda5203 100644
}
ib_dma_sync_single_for_device(dev, iu->dma, srp_max_iu_len,
@@ -1188,16 +1197,22 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
@@ -1188,16 +1204,22 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
if (__srp_post_send(target, iu, len, SRP_SEND_REQ)) {
shost_printk(KERN_ERR, target->scsi_host, PFX "Send failed\n");
@@ -1375,7 +1391,7 @@ index a2935e3..dda5203 100644
err:
return SCSI_MLQUEUE_HOST_BUSY;
}
@@ -1212,14 +1227,19 @@ static int srp_alloc_iu_bufs(struct srp_target_port *target)
@@ -1212,14 +1234,19 @@ static int srp_alloc_iu_bufs(struct srp_target_port *target)
GFP_KERNEL, DMA_FROM_DEVICE);
if (!target->rx_ring[i])
goto err;
@@ -1395,7 +1411,7 @@ index a2935e3..dda5203 100644
}
return 0;
@@ -1381,7 +1401,8 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
@@ -1381,7 +1408,8 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
break;
for (i = 0; i < SRP_RQ_SIZE; i++) {
@@ -1405,7 +1421,7 @@ index a2935e3..dda5203 100644
if (target->status)
break;
}
@@ -1451,8 +1472,6 @@ static int srp_send_tsk_mgmt(struct srp_target_port *target,
@@ -1451,8 +1479,6 @@ static int srp_send_tsk_mgmt(struct srp_target_port *target,
struct srp_iu *iu;
struct srp_tsk_mgmt *tsk_mgmt;
@@ -1414,7 +1430,7 @@ index a2935e3..dda5203 100644
if (target->state == SRP_TARGET_DEAD ||
target->state == SRP_TARGET_REMOVED) {
req->scmnd->result = DID_BAD_TARGET << 16;
@@ -1479,8 +1498,6 @@ static int srp_send_tsk_mgmt(struct srp_target_port *target,
@@ -1479,8 +1505,6 @@ static int srp_send_tsk_mgmt(struct srp_target_port *target,
req->tsk_mgmt = iu;
@@ -1423,7 +1439,7 @@ index a2935e3..dda5203 100644
if (!wait_for_completion_timeout(&req->done,
msecs_to_jiffies(SRP_ABORT_TIMEOUT_MS)))
return -1;
@@ -1488,7 +1505,6 @@ static int srp_send_tsk_mgmt(struct srp_target_port *target,
@@ -1488,7 +1512,6 @@ static int srp_send_tsk_mgmt(struct srp_target_port *target,
return 0;
out:
@@ -1431,7 +1447,7 @@ index a2935e3..dda5203 100644
return -1;
}
@@ -1519,8 +1535,6 @@ static int srp_abort(struct scsi_cmnd *scmnd)
@@ -1519,8 +1542,6 @@ static int srp_abort(struct scsi_cmnd *scmnd)
if (srp_send_tsk_mgmt(target, req, SRP_TSK_ABORT_TASK))
return FAILED;
@@ -1440,7 +1456,7 @@ index a2935e3..dda5203 100644
if (req->cmd_done) {
srp_remove_req(target, req);
scmnd->scsi_done(scmnd);
@@ -1530,15 +1544,14 @@ static int srp_abort(struct scsi_cmnd *scmnd)
@@ -1530,15 +1551,14 @@ static int srp_abort(struct scsi_cmnd *scmnd)
} else
ret = FAILED;
@@ -1458,7 +1474,7 @@ index a2935e3..dda5203 100644
shost_printk(KERN_ERR, target->scsi_host, "SRP reset_device called\n");
@@ -1551,14 +1564,10 @@ static int srp_reset_device(struct scsi_cmnd *scmnd)
@@ -1551,14 +1571,10 @@ static int srp_reset_device(struct scsi_cmnd *scmnd)
if (req->tsk_status)
return FAILED;
@@ -1475,7 +1491,51 @@ index a2935e3..dda5203 100644
return SUCCESS;
}
@@ -1981,6 +1990,7 @@ static ssize_t srp_create_target(struct device *dev,
@@ -1575,6 +1591,26 @@ static int srp_reset_host(struct scsi_cmnd *scmnd)
return ret;
}
+static ssize_t show_max_host_blocked(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct Scsi_Host *host = class_to_shost(dev);
+
+ return sprintf(buf, "%d\n", max(1U, host->max_host_blocked));
+}
+
+
+static ssize_t set_max_host_blocked(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct Scsi_Host *host = class_to_shost(dev);
+
+ host->max_host_blocked = max(1UL, simple_strtoul(buf, NULL, 0));
+ return count;
+}
+
static ssize_t show_id_ext(struct device *dev, struct device_attribute *attr,
char *buf)
{
@@ -1690,6 +1726,8 @@ static ssize_t show_local_ib_device(struct device *dev,
return sprintf(buf, "%s\n", target->srp_host->srp_dev->dev->name);
}
+static DEVICE_ATTR(max_host_blocked, S_IWUSR | S_IRUGO,
+ show_max_host_blocked, set_max_host_blocked);
static DEVICE_ATTR(id_ext, S_IRUGO, show_id_ext, NULL);
static DEVICE_ATTR(ioc_guid, S_IRUGO, show_ioc_guid, NULL);
static DEVICE_ATTR(service_id, S_IRUGO, show_service_id, NULL);
@@ -1702,6 +1740,7 @@ static DEVICE_ATTR(local_ib_port, S_IRUGO, show_local_ib_port, NULL);
static DEVICE_ATTR(local_ib_device, S_IRUGO, show_local_ib_device, NULL);
static struct device_attribute *srp_host_attrs[] = {
+ &dev_attr_max_host_blocked,
&dev_attr_id_ext,
&dev_attr_ioc_guid,
&dev_attr_service_id,
@@ -1981,6 +2020,7 @@ static ssize_t srp_create_target(struct device *dev,
target_host->transportt = ib_srp_transport_template;
target_host->max_lun = SRP_MAX_LUN;
target_host->max_cmd_len = sizeof ((struct srp_cmd *) (void *) 0L)->cdb;
@@ -1483,7 +1543,7 @@ index a2935e3..dda5203 100644
target = host_to_target(target_host);
@@ -1988,8 +1998,9 @@ static ssize_t srp_create_target(struct device *dev,
@@ -1988,8 +2028,9 @@ static ssize_t srp_create_target(struct device *dev,
target->scsi_host = target_host;
target->srp_host = host;
@@ -1494,7 +1554,7 @@ index a2935e3..dda5203 100644
for (i = 0; i < SRP_CMD_SQ_SIZE; ++i) {
target->req_ring[i].index = i;
list_add_tail(&target->req_ring[i].list, &target->free_reqs);
@@ -2200,6 +2211,7 @@ static void srp_remove_one(struct ib_device *device)
@@ -2200,6 +2241,7 @@ static void srp_remove_one(struct ib_device *device)
struct srp_host *host, *tmp_host;
LIST_HEAD(target_list);
struct srp_target_port *target, *tmp_target;
@@ -1502,7 +1562,7 @@ index a2935e3..dda5203 100644
srp_dev = ib_get_client_data(device, &srp_client);
@@ -2217,9 +2229,9 @@ static void srp_remove_one(struct ib_device *device)
@@ -2217,9 +2259,9 @@ static void srp_remove_one(struct ib_device *device)
*/
spin_lock(&host->target_lock);
list_for_each_entry(target, &host->target_list, list) {
@@ -1515,11 +1575,15 @@ index a2935e3..dda5203 100644
spin_unlock(&host->target_lock);
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index 854ec81..f665cea 100644
index 854ec81..1d5ab5d 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -148,19 +148,19 @@ struct srp_target_port {
@@ -146,21 +146,23 @@ struct srp_target_port {
struct ib_cq *recv_cq;
struct ib_cq *send_cq;
struct ib_qp *qp;
+ struct ib_wc send_wc[16];
+ struct ib_wc recv_wc[16];
int max_ti_iu_len;
+
@@ -1542,7 +1606,7 @@ index 854ec81..f665cea 100644
struct srp_request req_ring[SRP_CMD_SQ_SIZE];
struct work_struct work;
@@ -173,9 +173,11 @@ struct srp_target_port {
@@ -173,9 +175,11 @@ struct srp_target_port {
};
struct srp_iu {
@@ -1555,18 +1619,41 @@ index 854ec81..f665cea 100644
};
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index ad0ed21..3819d66 100644
index ad0ed21..2f9110c 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -749,11 +749,16 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
@@ -737,23 +737,31 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
goto out;
}
- spin_lock_irqsave(host->host_lock, flags);
- /*
- * AK: unlikely race here: for some reason the timer could
- * expire before the serial number is set up below.
- *
- * TODO: kill serial or move to blk layer
- */
- scsi_cmd_get_serial(host, cmd);
+ if (!host->unlocked_qcmds) {
+ spin_lock_irqsave(host->host_lock, flags);
+ /*
+ * AK: unlikely race here: for some reason the timer could
+ * expire before the serial number is set up below.
+ *
+ * TODO: kill serial or move to blk layer
+ */
+ scsi_cmd_get_serial(host, cmd);
+ } else
+ cmd->serial_number = 1;
if (unlikely(host->shost_state == SHOST_DEL)) {
+ if (host->unlocked_qcmds)
+ spin_lock_irqsave(host->host_lock, flags);
cmd->result = (DID_NO_CONNECT << 16);
scsi_done(cmd);
+ spin_unlock_irqrestore(host->host_lock, flags);
} else {
trace_scsi_dispatch_cmd_start(cmd);
+ if (host->unlocked_qcmds)
+ spin_unlock_irqrestore(host->host_lock, flags);
rtn = host->hostt->queuecommand(cmd, scsi_done);
+ if (!host->unlocked_qcmds)
+ spin_unlock_irqrestore(host->host_lock, flags);