[openib-general] [PATCH 1/1] IB/iser: return error code when PDUs may not be sent

[Erez Zilber]

Erez Zilber wrote:
> iSER limits the number of outstanding PDUs to send. When this threshold is
> reached, it should return an error code (-ENOBUFS) instead of setting the
> suspend_tx bit (which should be used only by libiscsi).
>
> Signed-off-by: Erez Zilber <erezz at voltaire.com>
> ---
>  drivers/infiniband/ulp/iser/iscsi_iser.c     |    4 ++--
>  drivers/infiniband/ulp/iser/iser_initiator.c |   26 ++++++++++++--------------
>  2 files changed, 14 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.c b/drivers/infiniband/ulp/iser/iscsi_iser.c
> index 9b2041e..dd221ed 100644
> --- a/drivers/infiniband/ulp/iser/iscsi_iser.c
> +++ b/drivers/infiniband/ulp/iser/iscsi_iser.c
> @@ -177,7 +177,7 @@ iscsi_iser_mtask_xmit(struct iscsi_conn 
>  	 * - if yes, the mtask is recycled at iscsi_complete_pdu
>  	 * - if no,  the mtask is recycled at iser_snd_completion
>  	 */
> -	if (error && error != -EAGAIN)
> +	if (error && error != -ENOBUFS)
>  		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
>  
>  	return error;
> @@ -241,7 +241,7 @@ iscsi_iser_ctask_xmit(struct iscsi_conn 
>  		error = iscsi_iser_ctask_xmit_unsol_data(conn, ctask);
>  
>   iscsi_iser_ctask_xmit_exit:
> -	if (error && error != -EAGAIN)
> +	if (error && error != -ENOBUFS)
>  		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
>  	return error;
>  }
> diff --git a/drivers/infiniband/ulp/iser/iser_initiator.c b/drivers/infiniband/ulp/iser/iser_initiator.c
> index e73c87b..0a7d1ab 100644
> --- a/drivers/infiniband/ulp/iser/iser_initiator.c
> +++ b/drivers/infiniband/ulp/iser/iser_initiator.c
> @@ -304,18 +304,14 @@ int iser_conn_set_full_featured_mode(str
>  static int
>  iser_check_xmit(struct iscsi_conn *conn, void *task)
>  {
> -	int rc = 0;
>  	struct iscsi_iser_conn *iser_conn = conn->dd_data;
>  
> -	write_lock_bh(conn->recv_lock);
>  	if (atomic_read(&iser_conn->ib_conn->post_send_buf_count) ==
>  	    ISER_QP_MAX_REQ_DTOS) {
> -		iser_dbg("%ld can't xmit task %p, suspending tx\n",jiffies,task);
> -		set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
> -		rc = -EAGAIN;
> +		iser_dbg("%ld can't xmit task %p\n",jiffies,task);
> +		return -ENOBUFS;
>  	}
> -	write_unlock_bh(conn->recv_lock);
> -	return rc;
> +	return 0;
>  }
>  
>  
> @@ -340,7 +336,7 @@ int iser_send_command(struct iscsi_conn 
>  		return -EPERM;
>  	}
>  	if (iser_check_xmit(conn, ctask))
> -		return -EAGAIN;
> +		return -ENOBUFS;
>  
>  	edtl = ntohl(hdr->data_length);
>  
> @@ -426,7 +422,7 @@ int iser_send_data_out(struct iscsi_conn
>  	}
>  
>  	if (iser_check_xmit(conn, ctask))
> -		return -EAGAIN;
> +		return -ENOBUFS;
>  
>  	itt = ntohl(hdr->itt);
>  	data_seg_len = ntoh24(hdr->dlength);
> @@ -498,7 +494,7 @@ int iser_send_control(struct iscsi_conn 
>  	}
>  
>  	if (iser_check_xmit(conn,mtask))
> -		return -EAGAIN;
> +		return -ENOBUFS;
>  
>  	/* build the tx desc regd header and add it to the tx desc dto */
>  	mdesc->type = ISCSI_TX_CONTROL;
> @@ -605,6 +601,7 @@ void iser_snd_completion(struct iser_des
>  	struct iscsi_iser_conn *iser_conn = ib_conn->iser_conn;
>  	struct iscsi_conn      *conn = iser_conn->iscsi_conn;
>  	struct iscsi_mgmt_task *mtask;
> +	int resume_tx = 0;
>  
>  	iser_dbg("Initiator, Data sent dto=0x%p\n", dto);
>  
> @@ -613,15 +610,16 @@ void iser_snd_completion(struct iser_des
>  	if (tx_desc->type == ISCSI_TX_DATAOUT)
>  		kmem_cache_free(ig.desc_cache, tx_desc);
>  
> +	if (atomic_read(&iser_conn->ib_conn->post_send_buf_count) ==
> +	    ISER_QP_MAX_REQ_DTOS)
> +		resume_tx = 1;
> +
>  	atomic_dec(&ib_conn->post_send_buf_count);
>  
> -	write_lock(conn->recv_lock);
> -	if (conn->suspend_tx) {
> +	if (resume_tx) {
>  		iser_dbg("%ld resuming tx\n",jiffies);
> -		clear_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
>  		scsi_queue_work(conn->session->host, &conn->xmitwork);
>  	}
> -	write_unlock(conn->recv_lock);
>  
>  	if (tx_desc->type == ISCSI_TX_CONTROL) {
>  		/* this arithmetic is legal by libiscsi dd_data allocation */
>   
Forgot to say: this patch is a bug fix for 2.6.20. Without it, iSER is
broken on 2.6.20.

Thanks,
-- 

____________________________________________________________

Erez Zilber   |  972-9-971-7689

Software Engineer, Storage Team

Voltaire – _The Grid Backbone_

 __

 www.voltaire.com <http://www.voltaire.com/>