IB/srp: stop sharing the host lock with SCSI
Bart Van Assche [Fri, 26 Nov 2010 20:08:38 +0000 (15:08 -0500)]
We don't need protection against the SCSI stack, so use our own lock to
allow parallel progress on separate CPUs.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[ broken out and small cleanups by David Dillow ]
Signed-off-by: David Dillow <dillowda@ornl.gov>

drivers/infiniband/ulp/srp/ib_srp.c
drivers/infiniband/ulp/srp/ib_srp.h

index e76fe54..8691fc8 100644 (file)
@@ -447,12 +447,12 @@ static bool srp_change_state(struct srp_target_port *target,
 {
        bool changed = false;
 
-       spin_lock_irq(target->scsi_host->host_lock);
+       spin_lock_irq(&target->lock);
        if (target->state == old) {
                target->state = new;
                changed = true;
        }
-       spin_unlock_irq(target->scsi_host->host_lock);
+       spin_unlock_irq(&target->lock);
        return changed;
 }
 
@@ -555,11 +555,11 @@ static void srp_remove_req(struct srp_target_port *target,
        unsigned long flags;
 
        srp_unmap_data(req->scmnd, target, req);
-       spin_lock_irqsave(target->scsi_host->host_lock, flags);
+       spin_lock_irqsave(&target->lock, flags);
        target->req_lim += req_lim_delta;
        req->scmnd = NULL;
        list_add_tail(&req->list, &target->free_reqs);
-       spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
+       spin_unlock_irqrestore(&target->lock, flags);
 }
 
 static void srp_reset_req(struct srp_target_port *target, struct srp_request *req)
@@ -634,13 +634,13 @@ err:
         * Schedule our work inside the lock to avoid a race with
         * the flush_scheduled_work() in srp_remove_one().
         */
-       spin_lock_irq(target->scsi_host->host_lock);
+       spin_lock_irq(&target->lock);
        if (target->state == SRP_TARGET_CONNECTING) {
                target->state = SRP_TARGET_DEAD;
                INIT_WORK(&target->work, srp_remove_work);
                schedule_work(&target->work);
        }
-       spin_unlock_irq(target->scsi_host->host_lock);
+       spin_unlock_irq(&target->lock);
 
        return ret;
 }
@@ -829,17 +829,16 @@ static void srp_put_tx_iu(struct srp_target_port *target, struct srp_iu *iu,
 {
        unsigned long flags;
 
-       spin_lock_irqsave(target->scsi_host->host_lock, flags);
+       spin_lock_irqsave(&target->lock, flags);
        list_add(&iu->list, &target->free_tx);
        if (iu_type != SRP_IU_RSP)
                ++target->req_lim;
-       spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
+       spin_unlock_irqrestore(&target->lock, flags);
 }
 
 /*
- * Must be called with target->scsi_host->host_lock held to protect
- * req_lim and free_tx.  If IU is not sent, it must be returned using
- * srp_put_tx_iu().
+ * Must be called with target->lock held to protect req_lim and free_tx.
+ * If IU is not sent, it must be returned using srp_put_tx_iu().
  *
  * Note:
  * An upper limit for the number of allocated information units for each
@@ -920,9 +919,9 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
        unsigned long flags;
 
        if (unlikely(rsp->tag & SRP_TAG_TSK_MGMT)) {
-               spin_lock_irqsave(target->scsi_host->host_lock, flags);
+               spin_lock_irqsave(&target->lock, flags);
                target->req_lim += be32_to_cpu(rsp->req_lim_delta);
-               spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
+               spin_unlock_irqrestore(&target->lock, flags);
 
                target->tsk_mgmt_status = -1;
                if (be32_to_cpu(rsp->resp_data_len) >= 4)
@@ -963,10 +962,10 @@ static int srp_response_common(struct srp_target_port *target, s32 req_delta,
        struct srp_iu *iu;
        int err;
 
-       spin_lock_irqsave(target->scsi_host->host_lock, flags);
+       spin_lock_irqsave(&target->lock, flags);
        target->req_lim += req_delta;
        iu = __srp_get_tx_iu(target, SRP_IU_RSP);
-       spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
+       spin_unlock_irqrestore(&target->lock, flags);
 
        if (!iu) {
                shost_printk(KERN_ERR, target->scsi_host, PFX
@@ -1131,14 +1130,14 @@ static int srp_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *scmnd)
                return 0;
        }
 
-       spin_lock_irqsave(shost->host_lock, flags);
+       spin_lock_irqsave(&target->lock, flags);
        iu = __srp_get_tx_iu(target, SRP_IU_CMD);
        if (iu) {
                req = list_first_entry(&target->free_reqs, struct srp_request,
                                      list);
                list_del(&req->list);
        }
-       spin_unlock_irqrestore(shost->host_lock, flags);
+       spin_unlock_irqrestore(&target->lock, flags);
 
        if (!iu)
                goto err;
@@ -1184,9 +1183,9 @@ err_unmap:
 err_iu:
        srp_put_tx_iu(target, iu, SRP_IU_CMD);
 
-       spin_lock_irqsave(shost->host_lock, flags);
+       spin_lock_irqsave(&target->lock, flags);
        list_add(&req->list, &target->free_reqs);
-       spin_unlock_irqrestore(shost->host_lock, flags);
+       spin_unlock_irqrestore(&target->lock, flags);
 
 err:
        return SCSI_MLQUEUE_HOST_BUSY;
@@ -1451,9 +1450,9 @@ static int srp_send_tsk_mgmt(struct srp_target_port *target,
 
        init_completion(&target->tsk_mgmt_done);
 
-       spin_lock_irq(target->scsi_host->host_lock);
+       spin_lock_irq(&target->lock);
        iu = __srp_get_tx_iu(target, SRP_IU_TSK_MGMT);
-       spin_unlock_irq(target->scsi_host->host_lock);
+       spin_unlock_irq(&target->lock);
 
        if (!iu)
                return -1;
@@ -1957,6 +1956,7 @@ static ssize_t srp_create_target(struct device *dev,
        target->scsi_host  = target_host;
        target->srp_host   = host;
 
+       spin_lock_init(&target->lock);
        INIT_LIST_HEAD(&target->free_tx);
        INIT_LIST_HEAD(&target->free_reqs);
        for (i = 0; i < SRP_CMD_SQ_SIZE; ++i) {
@@ -2186,9 +2186,9 @@ static void srp_remove_one(struct ib_device *device)
                 */
                spin_lock(&host->target_lock);
                list_for_each_entry(target, &host->target_list, list) {
-                       spin_lock_irq(target->scsi_host->host_lock);
+                       spin_lock_irq(&target->lock);
                        target->state = SRP_TARGET_REMOVED;
-                       spin_unlock_irq(target->scsi_host->host_lock);
+                       spin_unlock_irq(&target->lock);
                }
                spin_unlock(&host->target_lock);
 
index 81686ee..acb435d 100644 (file)
@@ -144,6 +144,8 @@ struct srp_target_port {
 
        struct srp_iu          *rx_ring[SRP_RQ_SIZE];
 
+       spinlock_t              lock;
+
        struct list_head        free_tx;
        struct srp_iu          *tx_ring[SRP_SQ_SIZE];