ionic: use index not pointer for queue tracking

Use index counters rather than pointers for tracking head
and tail in the queues to save a little memory and to perhaps
slightly faster queue processing.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: emusln

drivers/net/ethernet/pensando/ionic/ionic_debugfs.c

@@ -76,7 +76,7 @@ static int q_tail_show(struct seq_file *seq, void *v)
 {
 	struct ionic_queue *q = seq->private;
 
-	seq_printf(seq, "%d\n", q->tail->index);
+	seq_printf(seq, "%d\n", q->tail_idx);
 
 	return 0;
 }
@@ -86,7 +86,7 @@ static int q_head_show(struct seq_file *seq, void *v)
 {
 	struct ionic_queue *q = seq->private;
 
-	seq_printf(seq, "%d\n", q->head->index);
+	seq_printf(seq, "%d\n", q->head_idx);
 
 	return 0;
 }
@@ -96,7 +96,7 @@ static int cq_tail_show(struct seq_file *seq, void *v)
 {
 	struct ionic_cq *cq = seq->private;
 
-	seq_printf(seq, "%d\n", cq->tail->index);
+	seq_printf(seq, "%d\n", cq->tail_idx);
 
 	return 0;
 }

drivers/net/ethernet/pensando/ionic/ionic_dev.c

@@ -482,7 +482,7 @@ int ionic_cq_init(struct ionic_lif *lif, struct ionic_cq *cq,
 	cq->bound_intr = intr;
 	cq->num_descs = num_descs;
 	cq->desc_size = desc_size;
-	cq->tail = cq->info;
+	cq->tail_idx = 0;
 	cq->done_color = 1;
 
 	cur = cq->info;
@@ -522,15 +522,18 @@ unsigned int ionic_cq_service(struct ionic_cq *cq, unsigned int work_to_do,
 			      ionic_cq_cb cb, ionic_cq_done_cb done_cb,
 			      void *done_arg)
 {
+	struct ionic_cq_info *cq_info;
 	unsigned int work_done = 0;
 
 	if (work_to_do == 0)
 		return 0;
 
-	while (cb(cq, cq->tail)) {
-		if (cq->tail->last)
+	cq_info = &cq->info[cq->tail_idx];
+	while (cb(cq, cq_info)) {
+		if (cq->tail_idx == cq->num_descs - 1)
 			cq->done_color = !cq->done_color;
-		cq->tail = cq->tail->next;
+		cq->tail_idx = (cq->tail_idx + 1) & (cq->num_descs - 1);
+		cq_info = &cq->info[cq->tail_idx];
 		DEBUG_STATS_CQE_CNT(cq);
 
 		if (++work_done >= work_to_do)
@@ -565,8 +568,8 @@ int ionic_q_init(struct ionic_lif *lif, struct ionic_dev *idev,
 	q->num_descs = num_descs;
 	q->desc_size = desc_size;
 	q->sg_desc_size = sg_desc_size;
-	q->tail = q->info;
-	q->head = q->tail;
+	q->tail_idx = 0;
+	q->head_idx = 0;
 	q->pid = pid;
 
 	snprintf(q->name, sizeof(q->name), "L%d-%s%u", lif->index, name, index);
@@ -614,28 +617,31 @@ void ionic_q_post(struct ionic_queue *q, bool ring_doorbell, ionic_desc_cb cb,
 		  void *cb_arg)
 {
 	struct device *dev = q->lif->ionic->dev;
+	struct ionic_desc_info *desc_info;
 	struct ionic_lif *lif = q->lif;
 
-	q->head->cb = cb;
-	q->head->cb_arg = cb_arg;
-	q->head = q->head->next;
+	desc_info = &q->info[q->head_idx];
+	desc_info->cb = cb;
+	desc_info->cb_arg = cb_arg;
+
+	q->head_idx = (q->head_idx + 1) & (q->num_descs - 1);
 
 	dev_dbg(dev, "lif=%d qname=%s qid=%d qtype=%d p_index=%d ringdb=%d\n",
 		q->lif->index, q->name, q->hw_type, q->hw_index,
-		q->head->index, ring_doorbell);
+		q->head_idx, ring_doorbell);
 
 	if (ring_doorbell)
 		ionic_dbell_ring(lif->kern_dbpage, q->hw_type,
-				 q->dbval | q->head->index);
+				 q->dbval | q->head_idx);
 }
 
 static bool ionic_q_is_posted(struct ionic_queue *q, unsigned int pos)
 {
 	unsigned int mask, tail, head;
 
 	mask = q->num_descs - 1;
-	tail = q->tail->index;
-	head = q->head->index;
+	tail = q->tail_idx;
+	head = q->head_idx;
 
 	return ((pos - tail) & mask) < ((head - tail) & mask);
 }
@@ -648,18 +654,18 @@ void ionic_q_service(struct ionic_queue *q, struct ionic_cq_info *cq_info,
 	void *cb_arg;
 
 	/* check for empty queue */
-	if (q->tail->index == q->head->index)
+	if (q->tail_idx == q->head_idx)
 		return;
 
 	/* stop index must be for a descriptor that is not yet completed */
 	if (unlikely(!ionic_q_is_posted(q, stop_index)))
 		dev_err(q->lif->ionic->dev,
 			"ionic stop is not posted %s stop %u tail %u head %u\n",
-			q->name, stop_index, q->tail->index, q->head->index);
+			q->name, stop_index, q->tail_idx, q->head_idx);
 
 	do {
-		desc_info = q->tail;
-		q->tail = desc_info->next;
+		desc_info = &q->info[q->tail_idx];
+		q->tail_idx = (q->tail_idx + 1) & (q->num_descs - 1);
 
 		cb = desc_info->cb;
 		cb_arg = desc_info->cb_arg;

drivers/net/ethernet/pensando/ionic/ionic_dev.h

@@ -149,7 +149,13 @@ struct ionic_dev {
 };
 
 struct ionic_cq_info {
-	void *cq_desc;
+	union {
+		void *cq_desc;
+		struct ionic_txq_comp *txcq;
+		struct ionic_rxq_comp *rxcq;
+		struct ionic_admin_comp *admincq;
+		struct ionic_notifyq_event *notifyq;
+	};
 	struct ionic_cq_info *next;
 	unsigned int index;
 	bool last;
@@ -169,8 +175,17 @@ struct ionic_page_info {
 };
 
 struct ionic_desc_info {
-	void *desc;
-	void *sg_desc;
+	union {
+		void *desc;
+		struct ionic_txq_desc *txq_desc;
+		struct ionic_rxq_desc *rxq_desc;
+		struct ionic_admin_cmd *adminq_desc;
+	};
+	union {
+		void *sg_desc;
+		struct ionic_txq_sg_desc *txq_sg_desc;
+		struct ionic_rxq_sg_desc *rxq_sgl_desc;
+	};
 	struct ionic_desc_info *next;
 	unsigned int index;
 	unsigned int left;
@@ -183,22 +198,32 @@ struct ionic_desc_info {
 #define IONIC_QUEUE_NAME_MAX_SZ		32
 
 struct ionic_queue {
+	struct device *dev;
 	u64 dbell_count;
 	u64 drop;
 	u64 stop;
 	u64 wake;
 	struct ionic_lif *lif;
 	struct ionic_desc_info *info;
-	struct ionic_desc_info *tail;
-	struct ionic_desc_info *head;
 	struct ionic_dev *idev;
+	u16 head_idx;
+	u16 tail_idx;
 	unsigned int index;
 	unsigned int type;
 	unsigned int hw_index;
 	unsigned int hw_type;
 	u64 dbval;
-	void *base;
-	void *sg_base;
+	union {
+		void *base;
+		struct ionic_txq_desc *txq;
+		struct ionic_rxq_desc *rxq;
+		struct ionic_admin_cmd *adminq;
+	};
+	union {
+		void *sg_base;
+		struct ionic_txq_sg_desc *txq_sgl;
+		struct ionic_rxq_sg_desc *rxq_sgl;
+	};
 	dma_addr_t base_pa;
 	dma_addr_t sg_base_pa;
 	unsigned int num_descs;
@@ -225,9 +250,9 @@ struct ionic_cq {
 	dma_addr_t base_pa;
 	struct ionic_lif *lif;
 	struct ionic_cq_info *info;
-	struct ionic_cq_info *tail;
 	struct ionic_queue *bound_q;
 	struct ionic_intr_info *bound_intr;
+	u16 tail_idx;
 	bool done_color;
 	unsigned int num_descs;
 	u64 compl_count;
@@ -246,12 +271,12 @@ static inline void ionic_intr_init(struct ionic_dev *idev,
 
 static inline unsigned int ionic_q_space_avail(struct ionic_queue *q)
 {
-	unsigned int avail = q->tail->index;
+	unsigned int avail = q->tail_idx;
 
-	if (q->head->index >= avail)
-		avail += q->head->left - 1;
+	if (q->head_idx >= avail)
+		avail += q->num_descs - q->head_idx - 1;
 	else
-		avail -= q->head->index + 1;
+		avail -= q->head_idx + 1;
 
 	return avail;
 }

drivers/net/ethernet/pensando/ionic/ionic_lif.c

@@ -632,9 +632,9 @@ static int ionic_lif_txq_init(struct ionic_lif *lif, struct ionic_qcq *qcq)
 	dev_dbg(dev, "txq_init.ver %d\n", ctx.cmd.q_init.ver);
 	dev_dbg(dev, "txq_init.intr_index %d\n", ctx.cmd.q_init.intr_index);
 
-	q->tail = q->info;
-	q->head = q->tail;
-	cq->tail = cq->info;
+	q->tail_idx = 0;
+	q->head_idx = 0;
+	cq->tail_idx = 0;
 
 	err = ionic_adminq_post_wait(lif, &ctx);
 	if (err)
@@ -689,9 +689,9 @@ static int ionic_lif_rxq_init(struct ionic_lif *lif, struct ionic_qcq *qcq)
 	dev_dbg(dev, "rxq_init.ver %d\n", ctx.cmd.q_init.ver);
 	dev_dbg(dev, "rxq_init.intr_index %d\n", ctx.cmd.q_init.intr_index);
 
-	q->tail = q->info;
-	q->head = q->tail;
-	cq->tail = cq->info;
+	q->tail_idx = 0;
+	q->head_idx = 0;
+	cq->tail_idx = 0;
 
 	err = ionic_adminq_post_wait(lif, &ctx);
 	if (err)

drivers/net/ethernet/pensando/ionic/ionic_lif.h

@@ -244,14 +244,15 @@ int ionic_lif_rss_config(struct ionic_lif *lif, u16 types,
 
 int ionic_reset_queues(struct ionic_lif *lif, ionic_reset_cb cb, void *arg);
 
-static inline void debug_stats_txq_post(struct ionic_queue *q,
-					struct ionic_txq_desc *desc, bool dbell)
+static inline void debug_stats_txq_post(struct ionic_queue *q, bool dbell)
 {
-	u8 num_sg_elems = ((le64_to_cpu(desc->cmd) >> IONIC_TXQ_DESC_NSGE_SHIFT)
-						& IONIC_TXQ_DESC_NSGE_MASK);
+	struct ionic_txq_desc *desc = &q->txq[q->head_idx];
+	u8 num_sg_elems;
 
 	q->dbell_count += dbell;
 
+	num_sg_elems = ((le64_to_cpu(desc->cmd) >> IONIC_TXQ_DESC_NSGE_SHIFT)
+						& IONIC_TXQ_DESC_NSGE_MASK);
 	if (num_sg_elems > (IONIC_MAX_NUM_SG_CNTR - 1))
 		num_sg_elems = IONIC_MAX_NUM_SG_CNTR - 1;
 
@@ -272,8 +273,7 @@ static inline void debug_stats_napi_poll(struct ionic_qcq *qcq,
 #define DEBUG_STATS_CQE_CNT(cq)		((cq)->compl_count++)
 #define DEBUG_STATS_RX_BUFF_CNT(q)	((q)->lif->rxqstats[q->index].buffers_posted++)
 #define DEBUG_STATS_INTR_REARM(intr)	((intr)->rearm_count++)
-#define DEBUG_STATS_TXQ_POST(q, txdesc, dbell) \
-	debug_stats_txq_post(q, txdesc, dbell)
+#define DEBUG_STATS_TXQ_POST(q, dbell)  debug_stats_txq_post(q, dbell)
 #define DEBUG_STATS_NAPI_POLL(qcq, work_done) \
 	debug_stats_napi_poll(qcq, work_done)
 

drivers/net/ethernet/pensando/ionic/ionic_main.c

@@ -181,15 +181,17 @@ static const char *ionic_opcode_to_str(enum ionic_cmd_opcode opcode)
 
 static void ionic_adminq_flush(struct ionic_lif *lif)
 {
-	struct ionic_queue *adminq = &lif->adminqcq->q;
+	struct ionic_queue *q = &lif->adminqcq->q;
+	struct ionic_desc_info *desc_info;
 
 	spin_lock(&lif->adminq_lock);
 
-	while (adminq->tail != adminq->head) {
-		memset(adminq->tail->desc, 0, sizeof(union ionic_adminq_cmd));
-		adminq->tail->cb = NULL;
-		adminq->tail->cb_arg = NULL;
-		adminq->tail = adminq->tail->next;
+	while (q->tail_idx != q->head_idx) {
+		desc_info = &q->info[q->tail_idx];
+		memset(desc_info->desc, 0, sizeof(union ionic_adminq_cmd));
+		desc_info->cb = NULL;
+		desc_info->cb_arg = NULL;
+		q->tail_idx = (q->tail_idx + 1) & (q->num_descs - 1);
 	}
 	spin_unlock(&lif->adminq_lock);
 }
@@ -245,18 +247,19 @@ static void ionic_adminq_cb(struct ionic_queue *q,
 
 static int ionic_adminq_post(struct ionic_lif *lif, struct ionic_admin_ctx *ctx)
 {
-	struct ionic_queue *adminq;
+	struct ionic_desc_info *desc_info;
+	struct ionic_queue *q;
 	int err = 0;
 
 	WARN_ON(in_interrupt());
 
 	if (!lif->adminqcq)
 		return -EIO;
 
-	adminq = &lif->adminqcq->q;
+	q = &lif->adminqcq->q;
 
 	spin_lock(&lif->adminq_lock);
-	if (!ionic_q_has_space(adminq, 1)) {
+	if (!ionic_q_has_space(q, 1)) {
 		err = -ENOSPC;
 		goto err_out;
 	}
@@ -265,13 +268,14 @@ static int ionic_adminq_post(struct ionic_lif *lif, struct ionic_admin_ctx *ctx)
 	if (err)
 		goto err_out;
 
-	memcpy(adminq->head->desc, &ctx->cmd, sizeof(ctx->cmd));
+	desc_info = &q->info[q->head_idx];
+	memcpy(desc_info->desc, &ctx->cmd, sizeof(ctx->cmd));
 
 	dev_dbg(&lif->netdev->dev, "post admin queue command:\n");
 	dynamic_hex_dump("cmd ", DUMP_PREFIX_OFFSET, 16, 1,
 			 &ctx->cmd, sizeof(ctx->cmd), true);
 
-	ionic_q_post(adminq, true, ionic_adminq_cb, ctx);
+	ionic_q_post(q, true, ionic_adminq_cb, ctx);
 
 err_out:
 	spin_unlock(&lif->adminq_lock);