[ofa-general][PATCH 1/4] SRP fail-over faster

[ofa-general][PATCH 1/4] SRP fail-over faster

[Vu Pham]

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Recreating qp, cq at reconnect instead of re-use them. We need this so 
that we don't have to wait on disconnect connection

Signed-off-by: Vu Pham <vu-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>



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---
 drivers/infiniband/ulp/srp/ib_srp.c |   22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

Index: ofed_kernel/drivers/infiniband/ulp/srp/ib_srp.c
===================================================================
--- ofed_kernel.orig/drivers/infiniband/ulp/srp/ib_srp.c
+++ ofed_kernel/drivers/infiniband/ulp/srp/ib_srp.c
@@ -537,10 +537,10 @@ static void srp_reset_req(struct srp_tar
 
 static int srp_reconnect_target(struct srp_target_port *target)
 {
-	struct ib_qp_attr qp_attr;
 	struct srp_request *req, *tmp;
-	struct ib_wc wc;
 	int ret;
+	struct ib_cq *old_cq;
+	struct ib_qp *old_qp;
 
 	spin_lock_irq(target->scsi_host->host_lock);
 	if (target->state != SRP_TARGET_LIVE) {
@@ -559,17 +559,17 @@ static int srp_reconnect_target(struct s
 	if (ret)
 		goto err;
 
-	qp_attr.qp_state = IB_QPS_RESET;
-	ret = ib_modify_qp(target->qp, &qp_attr, IB_QP_STATE);
-	if (ret)
-		goto err;
-
-	ret = srp_init_qp(target, target->qp);
-	if (ret)
+	old_qp = target->qp;
+	old_cq = target->cq;
+	ret = srp_create_target_ib(target);
+	if (ret) {
+		target->qp = old_qp;
+		target->cq = old_cq;
 		goto err;
+	}
 
-	while (ib_poll_cq(target->cq, 1, &wc) > 0)
-		; /* nothing */
+	ib_destroy_qp(old_qp);
+	ib_destroy_cq(old_cq);
 
 	spin_lock_irq(target->scsi_host->host_lock);
 	list_for_each_entry_safe(req, tmp, &target->req_queue, list)

Re: [ofa-general][PATCH 1/4] SRP fail-over faster

[Roland Dreier]

One meta comment: when sending a series of 4 patches, please choose a
descriptive subject for each one.  We don't want the same headline in
the kernel log for all 4 patches.

 > -	qp_attr.qp_state = IB_QPS_RESET;
 > -	ret = ib_modify_qp(target->qp, &qp_attr, IB_QP_STATE);
 > -	if (ret)
 > -		goto err;
 > -
 > -	ret = srp_init_qp(target, target->qp);
 > -	if (ret)
 > +	old_qp = target->qp;
 > +	old_cq = target->cq;
 > +	ret = srp_create_target_ib(target);

I don't understand why this is any faster?  Is creating a new QP really
any different from modifying an old QP to reset state?
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Re: [ofa-general][PATCH 1/4] SRP fail-over faster

[Vu Pham]

Roland Dreier wrote:
> One meta comment: when sending a series of 4 patches, please choose a
> descriptive subject for each one.  We don't want the same headline in
> the kernel log for all 4 patches.
>
>   
I'll remember next time
>  > -	qp_attr.qp_state = IB_QPS_RESET;
>  > -	ret = ib_modify_qp(target->qp, &qp_attr, IB_QP_STATE);
>  > -	if (ret)
>  > -		goto err;
>  > -
>  > -	ret = srp_init_qp(target, target->qp);
>  > -	if (ret)
>  > +	old_qp = target->qp;
>  > +	old_cq = target->cq;
>  > +	ret = srp_create_target_ib(target);
>
> I don't understand why this is any faster?  Is creating a new QP really
> any different from modifying an old QP to reset state?
>   

It is not; it is needed for patch 2/4 disconnect without wait and it is 
faster that way
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