Re: [PATCH 7/8] be2iscsi: Fix processing cqe for cxn whose endpoint is freed

[Mike Christie <michaelc@cs.wisc.edu>]

On 05/05/2014 08:41 PM, Jay Kallickal wrote:
> From: Jayamohan Kallickal <jayamohan.kallickal@emulex.com>
> 
>  During heavy IO in multipath environment with many active sessions
>  and port-bouncing happening, there is a race condition because of
>  which beiscsi_prcess_cqe() gets called for a connection whose
>  endpoint is freed.
> 
>  Checking endpoint reference for a connection before processing in
>  beiscsi_process_cq().
> 
> Signed-off-by: Minh Tran <minhduc.tran@emulex.com>
> Signed-off-by: John Soni Jose <sony.john-n@emulex.com>
> Signed-off-by: Jayamohan Kallickal <jayamohan.kallickal@emulex.com>
> ---
>  drivers/scsi/be2iscsi/be_main.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/scsi/be2iscsi/be_main.c b/drivers/scsi/be2iscsi/be_main.c
> index dccda6c..5a7022f 100644
> --- a/drivers/scsi/be2iscsi/be_main.c
> +++ b/drivers/scsi/be2iscsi/be_main.c
> @@ -2110,6 +2110,16 @@ static unsigned int beiscsi_process_cq(struct be_eq_obj *pbe_eq)
>  
>  		cri_index = BE_GET_CRI_FROM_CID(cid);
>  		ep = phba->ep_array[cri_index];
> +		if (unlikely(ep == NULL)) {
> +			/* connection has already been freed
> +			 * just move on to next one
> +			 */
> +			beiscsi_log(phba, KERN_WARNING,
> +				    BEISCSI_LOG_INIT,
> +				    "BM_%d : proc cqe of disconn ep: cid %d\n",
> +				    cid);
> +			goto proc_next_cqe;
> +		}
>  		beiscsi_ep = ep->dd_data;
>  		beiscsi_conn = beiscsi_ep->conn;
>  

It looks like if that race is possible then we could also free the ep
while you are accessing right? I think you would need to get a ref to
the ep.

What command/function tells the card to stop sending the driver
events/notifications/ios for that connection? Is it beiscsi_close_conn
or mgmt_invalidate_connection?