cxgb4: Add FL DMA mapping error and low counter

Add Free List DMA Mapping Errors to SGE Queue info for
Free Lists. Add Free List "Low" counter to count the number of times we
see the number of pointers that we _think_ the hardware sees in the
Free List below the Egress Threshold.

Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cxgb4.h

@@ -483,6 +483,8 @@ struct sge_fl {                     /* SGE free-buffer queue state */
 	unsigned int pidx;          /* producer index */
 	unsigned long alloc_failed; /* # of times buffer allocation failed */
 	unsigned long large_alloc_failed;
+	unsigned long mapping_err;  /* # of RX Buffer DMA Mapping failures */
+	unsigned long low;          /* # of times momentarily starving */
 	unsigned long starving;
 	/* RO fields */
 	unsigned int cntxt_id;      /* SGE context id for the free list */

drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c

@@ -2325,6 +2325,8 @@ do { \
 		TL("TxMapErr:", mapping_err);
 		RL("FLAllocErr:", fl.alloc_failed);
 		RL("FLLrgAlcErr:", fl.large_alloc_failed);
+		RL("FLMapErr:", fl.mapping_err);
+		RL("FLLow:", fl.low);
 		RL("FLStarving:", fl.starving);
 
 	} else if (iscsi_idx < iscsi_entries) {
@@ -2359,6 +2361,8 @@ do { \
 		RL("RxNoMem:", stats.nomem);
 		RL("FLAllocErr:", fl.alloc_failed);
 		RL("FLLrgAlcErr:", fl.large_alloc_failed);
+		RL("FLMapErr:", fl.mapping_err);
+		RL("FLLow:", fl.low);
 		RL("FLStarving:", fl.starving);
 
 	} else if (rdma_idx < rdma_entries) {
@@ -2388,6 +2392,8 @@ do { \
 		RL("RxNoMem:", stats.nomem);
 		RL("FLAllocErr:", fl.alloc_failed);
 		RL("FLLrgAlcErr:", fl.large_alloc_failed);
+		RL("FLMapErr:", fl.mapping_err);
+		RL("FLLow:", fl.low);
 		RL("FLStarving:", fl.starving);
 
 	} else if (ciq_idx < ciq_entries) {

drivers/net/ethernet/chelsio/cxgb4/sge.c

@@ -613,6 +613,7 @@ static unsigned int refill_fl(struct adapter *adap, struct sge_fl *q, int n,
 				       PCI_DMA_FROMDEVICE);
 		if (unlikely(dma_mapping_error(adap->pdev_dev, mapping))) {
 			__free_pages(pg, s->fl_pg_order);
+			q->mapping_err++;
 			goto out;   /* do not try small pages for this error */
 		}
 		mapping |= RX_LARGE_PG_BUF;
@@ -642,6 +643,7 @@ alloc_small_pages:
 				       PCI_DMA_FROMDEVICE);
 		if (unlikely(dma_mapping_error(adap->pdev_dev, mapping))) {
 			put_page(pg);
+			q->mapping_err++;
 			goto out;
 		}
 		*d++ = cpu_to_be64(mapping);
@@ -663,6 +665,7 @@ out:	cred = q->avail - cred;
 
 	if (unlikely(fl_starving(adap, q))) {
 		smp_wmb();
+		q->low++;
 		set_bit(q->cntxt_id - adap->sge.egr_start,
 			adap->sge.starving_fl);
 	}