net: octeontx2: Fix the confusion in buffer alloc failure path

Pavel pointed that the return of dma_addr_t in
otx2_alloc_rbuf/__otx2_alloc_rbuf() seem suspicious because a negative
error code may be returned in some cases. For a dma_addr_t, the error
code such as -ENOMEM does seem a valid value, so we can't judge if the
buffer allocation fail or not based on that value. Add a parameter for
otx2_alloc_rbuf/__otx2_alloc_rbuf() to store the dma address and make
the return value to indicate if the buffer allocation really fail or
not.

Reported-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Tested-by: Subbaraya Sundeep <sbhatta@marvell.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c

@@ -483,33 +483,34 @@ void otx2_config_irq_coalescing(struct otx2_nic *pfvf, int qidx)
 		     (pfvf->hw.cq_ecount_wait - 1));
 }
 
-dma_addr_t __otx2_alloc_rbuf(struct otx2_nic *pfvf, struct otx2_pool *pool)
+int __otx2_alloc_rbuf(struct otx2_nic *pfvf, struct otx2_pool *pool,
+		      dma_addr_t *dma)
 {
-	dma_addr_t iova;
 	u8 *buf;
 
 	buf = napi_alloc_frag_align(pool->rbsize, OTX2_ALIGN);
 	if (unlikely(!buf))
 		return -ENOMEM;
 
-	iova = dma_map_single_attrs(pfvf->dev, buf, pool->rbsize,
+	*dma = dma_map_single_attrs(pfvf->dev, buf, pool->rbsize,
 				    DMA_FROM_DEVICE, DMA_ATTR_SKIP_CPU_SYNC);
-	if (unlikely(dma_mapping_error(pfvf->dev, iova))) {
+	if (unlikely(dma_mapping_error(pfvf->dev, *dma))) {
 		page_frag_free(buf);
 		return -ENOMEM;
 	}
 
-	return iova;
+	return 0;
 }
 
-static dma_addr_t otx2_alloc_rbuf(struct otx2_nic *pfvf, struct otx2_pool *pool)
+static int otx2_alloc_rbuf(struct otx2_nic *pfvf, struct otx2_pool *pool,
+			   dma_addr_t *dma)
 {
-	dma_addr_t addr;
+	int ret;
 
 	local_bh_disable();
-	addr = __otx2_alloc_rbuf(pfvf, pool);
+	ret = __otx2_alloc_rbuf(pfvf, pool, dma);
 	local_bh_enable();
-	return addr;
+	return ret;
 }
 
 void otx2_tx_timeout(struct net_device *netdev, unsigned int txq)
@@ -903,7 +904,7 @@ static void otx2_pool_refill_task(struct work_struct *work)
 	struct refill_work *wrk;
 	int qidx, free_ptrs = 0;
 	struct otx2_nic *pfvf;
-	s64 bufptr;
+	dma_addr_t bufptr;
 
 	wrk = container_of(work, struct refill_work, pool_refill_work.work);
 	pfvf = wrk->pf;
@@ -913,8 +914,7 @@ static void otx2_pool_refill_task(struct work_struct *work)
 	free_ptrs = cq->pool_ptrs;
 
 	while (cq->pool_ptrs) {
-		bufptr = otx2_alloc_rbuf(pfvf, rbpool);
-		if (bufptr <= 0) {
+		if (otx2_alloc_rbuf(pfvf, rbpool, &bufptr)) {
 			/* Schedule a WQ if we fails to free atleast half of the
 			 * pointers else enable napi for this RQ.
 			 */
@@ -1213,8 +1213,8 @@ int otx2_sq_aura_pool_init(struct otx2_nic *pfvf)
 	struct otx2_hw *hw = &pfvf->hw;
 	struct otx2_snd_queue *sq;
 	struct otx2_pool *pool;
+	dma_addr_t bufptr;
 	int err, ptr;
-	s64 bufptr;
 
 	/* Calculate number of SQBs needed.
 	 *
@@ -1259,9 +1259,8 @@ int otx2_sq_aura_pool_init(struct otx2_nic *pfvf)
 			return -ENOMEM;
 
 		for (ptr = 0; ptr < num_sqbs; ptr++) {
-			bufptr = otx2_alloc_rbuf(pfvf, pool);
-			if (bufptr <= 0)
-				return bufptr;
+			if (otx2_alloc_rbuf(pfvf, pool, &bufptr))
+				return -ENOMEM;
 			otx2_aura_freeptr(pfvf, pool_id, bufptr);
 			sq->sqb_ptrs[sq->sqb_count++] = (u64)bufptr;
 		}
@@ -1280,7 +1279,7 @@ int otx2_rq_aura_pool_init(struct otx2_nic *pfvf)
 	int stack_pages, pool_id, rq;
 	struct otx2_pool *pool;
 	int err, ptr, num_ptrs;
-	s64 bufptr;
+	dma_addr_t bufptr;
 
 	num_ptrs = pfvf->qset.rqe_cnt;
 
@@ -1310,9 +1309,8 @@ int otx2_rq_aura_pool_init(struct otx2_nic *pfvf)
 	for (pool_id = 0; pool_id < hw->rqpool_cnt; pool_id++) {
 		pool = &pfvf->qset.pool[pool_id];
 		for (ptr = 0; ptr < num_ptrs; ptr++) {
-			bufptr = otx2_alloc_rbuf(pfvf, pool);
-			if (bufptr <= 0)
-				return bufptr;
+			if (otx2_alloc_rbuf(pfvf, pool, &bufptr))
+				return -ENOMEM;
 			otx2_aura_freeptr(pfvf, pool_id,
 					  bufptr + OTX2_HEAD_ROOM);
 		}

drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.h

@@ -485,9 +485,9 @@ static inline u64 otx2_aura_allocptr(struct otx2_nic *pfvf, int aura)
 
 /* Free pointer to a pool/aura */
 static inline void otx2_aura_freeptr(struct otx2_nic *pfvf,
-				     int aura, s64 buf)
+				     int aura, u64 buf)
 {
-	otx2_write128((u64)buf, (u64)aura | BIT_ULL(63),
+	otx2_write128(buf, (u64)aura | BIT_ULL(63),
 		      otx2_get_regaddr(pfvf, NPA_LF_AURA_OP_FREE0));
 }
 
@@ -636,7 +636,8 @@ int otx2_txschq_config(struct otx2_nic *pfvf, int lvl);
 int otx2_txsch_alloc(struct otx2_nic *pfvf);
 int otx2_txschq_stop(struct otx2_nic *pfvf);
 void otx2_sqb_flush(struct otx2_nic *pfvf);
-dma_addr_t __otx2_alloc_rbuf(struct otx2_nic *pfvf, struct otx2_pool *pool);
+int __otx2_alloc_rbuf(struct otx2_nic *pfvf, struct otx2_pool *pool,
+		      dma_addr_t *dma);
 int otx2_rxtx_enable(struct otx2_nic *pfvf, bool enable);
 void otx2_ctx_disable(struct mbox *mbox, int type, bool npa);
 int otx2_nix_config_bp(struct otx2_nic *pfvf, bool enable);

drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c

@@ -304,7 +304,7 @@ static int otx2_rx_napi_handler(struct otx2_nic *pfvf,
 {
 	struct nix_cqe_rx_s *cqe;
 	int processed_cqe = 0;
-	s64 bufptr;
+	dma_addr_t bufptr;
 
 	while (likely(processed_cqe < budget)) {
 		cqe = (struct nix_cqe_rx_s *)CQE_ADDR(cq, cq->cq_head);
@@ -333,8 +333,7 @@ static int otx2_rx_napi_handler(struct otx2_nic *pfvf,
 
 	/* Refill pool with new buffers */
 	while (cq->pool_ptrs) {
-		bufptr = __otx2_alloc_rbuf(pfvf, cq->rbpool);
-		if (unlikely(bufptr <= 0)) {
+		if (unlikely(__otx2_alloc_rbuf(pfvf, cq->rbpool, &bufptr))) {
 			struct refill_work *work;
 			struct delayed_work *dwork;