Re: [PATCH v1] IB/ipoib: Skip napi_schedule if ib_poll_cq fails

[Eli Cohen <eli-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>]

Reviewd-by: Eli Cohen <eli-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>

BTW, did you actually hit this or are you sending this based on code
review?

On Wed, Jul 13, 2016 at 03:21:13AM -0700, Yuval Shaia wrote:
> To avoid entering into endless loop when device can't poll CQE from CQ
> driver should not reschedule if error is not -EAGAIN.
> 
> Signed-off-by: Yuval Shaia <yuval.shaia-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
> ---
>  drivers/infiniband/ulp/ipoib/ipoib.h       |    5 +++++
>  drivers/infiniband/ulp/ipoib/ipoib_ib.c    |   13 ++++++++++++-
>  drivers/infiniband/ulp/ipoib/ipoib_verbs.c |    1 +
>  3 files changed, 18 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h
> index 4f7d9b4..1946149 100644
> --- a/drivers/infiniband/ulp/ipoib/ipoib.h
> +++ b/drivers/infiniband/ulp/ipoib/ipoib.h
> @@ -116,6 +116,8 @@ enum {
>  	IPOIB_NON_CHILD		  = 0,
>  	IPOIB_LEGACY_CHILD	  = 1,
>  	IPOIB_RTNL_CHILD	  = 2,
> +
> +	IPOIB_MAX_CONSEQ_CQ_ERR	  = 10,
>  };
>  
>  #define	IPOIB_OP_RECV   (1ul << 31)
> @@ -347,6 +349,7 @@ struct ipoib_dev_priv {
>  	u16		  pkey_index;
>  	struct ib_pd	 *pd;
>  	struct ib_cq	 *recv_cq;
> +	int		  recv_conseq_cq_errs;
>  	struct ib_cq	 *send_cq;
>  	struct ib_qp	 *qp;
>  	u32		  qkey;
> @@ -772,6 +775,8 @@ static inline void ipoib_unregister_debugfs(void) { }
>  	printk(level "%s: " format, ((struct ipoib_dev_priv *) priv)->dev->name , ## arg)
>  #define ipoib_warn(priv, format, arg...)		\
>  	ipoib_printk(KERN_WARNING, priv, format , ## arg)
> +#define ipoib_crit(priv, format, arg...)		\
> +	ipoib_printk(KERN_CRIT, priv, format , ## arg)
>  
>  extern int ipoib_sendq_size;
>  extern int ipoib_recvq_size;
> diff --git a/drivers/infiniband/ulp/ipoib/ipoib_ib.c b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
> index dc6d241..9395a24 100644
> --- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c
> +++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
> @@ -449,7 +449,8 @@ int ipoib_poll(struct napi_struct *napi, int budget)
>  	int t;
>  	int n, i;
>  
> -	done  = 0;
> +	done = 0;
> +	n = 0;
>  
>  poll_more:
>  	while (done < budget) {
> @@ -475,6 +476,16 @@ poll_more:
>  			break;
>  	}
>  
> +	if (unlikely(n < 0) && (n != -EAGAIN)) {
> +		if (priv->recv_conseq_cq_errs++ >= IPOIB_MAX_CONSEQ_CQ_ERR) {
> +			ipoib_crit(priv,
> +				   "Too many poll_cq errors, last error: %d\n",
> +				   n);
> +			return done;
> +		}
> +	} else
> +		priv->recv_conseq_cq_errs = 0;
> +
>  	if (done < budget) {
>  		napi_complete(napi);
>  		if (unlikely(ib_req_notify_cq(priv->recv_cq,
> diff --git a/drivers/infiniband/ulp/ipoib/ipoib_verbs.c b/drivers/infiniband/ulp/ipoib/ipoib_verbs.c
> index 1e7cbba..6ca8bdd 100644
> --- a/drivers/infiniband/ulp/ipoib/ipoib_verbs.c
> +++ b/drivers/infiniband/ulp/ipoib/ipoib_verbs.c
> @@ -181,6 +181,7 @@ int ipoib_transport_dev_init(struct net_device *dev, struct ib_device *ca)
>  		printk(KERN_WARNING "%s: failed to create receive CQ\n", ca->name);
>  		goto out_cm_dev_cleanup;
>  	}
> +	priv->recv_conseq_cq_errs = 0;
>  
>  	cq_attr.cqe = ipoib_sendq_size;
>  	priv->send_cq = ib_create_cq(priv->ca, ipoib_send_comp_handler, NULL,
> -- 
> 1.7.1
> 
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