[PATCH 21.11] net/ionic: add watchdogs to protect each queue type

[Andrew Boyer]

Ring the doorbell again for the following scenarios:
 * No receives posted but Rx queue not empty after deadline
 * No transmits posted but Tx work still pending after deadline
 * Admin queue work still pending after deadline

This will help the queues recover in the extremely rare case that
a doorbell is missed by the FW.

Signed-off-by: Andrew Boyer <andrew.boyer at amd.com>
Signed-off-by: R Mohamed Shah <mohamedshah.r at amd.com>
---
 drivers/net/ionic/ionic_dev.h  |  4 +++
 drivers/net/ionic/ionic_lif.h  |  3 ++
 drivers/net/ionic/ionic_main.c | 22 +++++++++++++++
 drivers/net/ionic/ionic_rxtx.c | 50 ++++++++++++++++++++++++++++++++++
 4 files changed, 79 insertions(+)

diff --git a/drivers/net/ionic/ionic_dev.h b/drivers/net/ionic/ionic_dev.h
index 38c078efdf..30a8ebe1aa 100644
--- a/drivers/net/ionic/ionic_dev.h
+++ b/drivers/net/ionic/ionic_dev.h
@@ -23,6 +23,10 @@
 #define IONIC_DEVCMD_TIMEOUT		5	/* devcmd_timeout */
 #define IONIC_DEVCMD_CHECK_PERIOD_US	10	/* devcmd status chk period */
 
+#define IONIC_Q_WDOG_MS			10	/* 10ms */
+#define IONIC_Q_WDOG_MAX_MS		5000	/* 5s */
+#define IONIC_ADMINQ_WDOG_MS		500	/* 500ms */
+
 #define	IONIC_ALIGN             4096
 
 struct ionic_adapter;
diff --git a/drivers/net/ionic/ionic_lif.h b/drivers/net/ionic/ionic_lif.h
index 9f00ba2973..eac6a58aaa 100644
--- a/drivers/net/ionic/ionic_lif.h
+++ b/drivers/net/ionic/ionic_lif.h
@@ -81,6 +81,8 @@ struct ionic_rx_qcq {
 
 	/* cacheline2 */
 	struct rte_mempool *mb_pool;
+	uint64_t last_wdog_cycles;
+	uint64_t wdog_ms;
 	uint16_t flags;
 
 	/* cacheline3 (inside stats) */
@@ -92,6 +94,7 @@ struct ionic_tx_qcq {
 	struct ionic_qcq qcq;
 
 	/* cacheline2 */
+	uint64_t last_wdog_cycles;
 	uint16_t num_segs_fw;	/* # segs supported by current FW */
 	uint16_t flags;
 
diff --git a/drivers/net/ionic/ionic_main.c b/drivers/net/ionic/ionic_main.c
index 7301f53342..3d1915daa7 100644
--- a/drivers/net/ionic/ionic_main.c
+++ b/drivers/net/ionic/ionic_main.c
@@ -230,10 +230,16 @@ static int
 ionic_adminq_wait_for_completion(struct ionic_lif *lif,
 		struct ionic_admin_ctx *ctx, unsigned long max_wait)
 {
+	struct ionic_queue *q = &lif->adminqcq->qcq.q;
 	unsigned long step_usec = IONIC_DEVCMD_CHECK_PERIOD_US;
+	unsigned long step_deadline;
 	unsigned long max_wait_usec = max_wait * 1000000L;
 	unsigned long elapsed_usec = 0;
 	int budget = 8;
+	uint16_t idx;
+	void **info;
+
+	step_deadline = IONIC_ADMINQ_WDOG_MS * 1000 / step_usec;
 
 	while (ctx->pending_work && elapsed_usec < max_wait_usec) {
 		/*
@@ -245,10 +251,26 @@ ionic_adminq_wait_for_completion(struct ionic_lif *lif,
 		ionic_qcq_service(&lif->adminqcq->qcq, budget,
 				ionic_adminq_service, NULL);
 
+		/*
+		 * Ring the doorbell again if work is pending after deadline.
+		 */
+		if (ctx->pending_work && !step_deadline) {
+			step_deadline = IONIC_ADMINQ_WDOG_MS *
+				1000 / step_usec;
+
+			rte_spinlock_lock(&lif->adminq_lock);
+			idx = Q_NEXT_TO_POST(q, -1);
+			info = IONIC_INFO_PTR(q, idx);
+			if (info[0] == ctx)
+				ionic_q_flush(q);
+			rte_spinlock_unlock(&lif->adminq_lock);
+		}
+
 		rte_spinlock_unlock(&lif->adminq_service_lock);
 
 		rte_delay_us_block(step_usec);
 		elapsed_usec += step_usec;
+		step_deadline--;
 	}
 
 	return (!ctx->pending_work);
diff --git a/drivers/net/ionic/ionic_rxtx.c b/drivers/net/ionic/ionic_rxtx.c
index 9f602de6a9..029b827e59 100644
--- a/drivers/net/ionic/ionic_rxtx.c
+++ b/drivers/net/ionic/ionic_rxtx.c
@@ -536,6 +536,7 @@ ionic_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 	uint32_t next_q_head_idx;
 	uint32_t bytes_tx = 0;
 	uint16_t nb_avail, nb_tx = 0;
+	uint64_t then, now, hz, delta;
 	int err;
 
 	/* Cleaning old buffers */
@@ -571,6 +572,24 @@ ionic_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 	if (nb_tx > 0) {
 		rte_wmb();
 		ionic_q_flush(q);
+
+		txq->last_wdog_cycles = rte_get_timer_cycles();
+	} else {
+		/*
+		 * Ring the doorbell again if no work could be posted and work
+		 * is still pending after the deadline.
+		 */
+		if (q->head_idx != q->tail_idx) {
+			then = txq->last_wdog_cycles;
+			now = rte_get_timer_cycles();
+			hz = rte_get_timer_hz();
+			delta = (now - then) * 1000;
+
+			if (delta >= hz * IONIC_Q_WDOG_MS) {
+				ionic_q_flush(q);
+				txq->last_wdog_cycles = now;
+			}
+		}
 	}
 
 	stats->packets += nb_tx;
@@ -1059,6 +1078,7 @@ ionic_rxq_service(struct ionic_rx_qcq *rxq, uint32_t work_to_do,
 	bool more;
 	uint32_t curr_q_tail_idx, curr_cq_tail_idx;
 	uint32_t work_done = 0;
+	uint64_t then, now, hz, delta;
 
 	if (work_to_do == 0)
 		return;
@@ -1096,6 +1116,36 @@ ionic_rxq_service(struct ionic_rx_qcq *rxq, uint32_t work_to_do,
 
 		cq_desc = &cq_desc_base[cq->tail_idx];
 	}
+
+	if (work_done) {
+		rxq->last_wdog_cycles = rte_get_timer_cycles();
+		rxq->wdog_ms = IONIC_Q_WDOG_MS;
+	} else {
+		/*
+		 * Ring the doorbell again if no recvs were posted and the
+		 * recv queue is not empty after the deadline.
+		 *
+		 * Exponentially back off the deadline to avoid excessive
+		 * doorbells when the recv queue is idle.
+		 */
+		if (q->head_idx != q->tail_idx) {
+			then = rxq->last_wdog_cycles;
+			now = rte_get_timer_cycles();
+			hz = rte_get_timer_hz();
+			delta = (now - then) * 1000;
+
+			if (delta >= hz * rxq->wdog_ms) {
+				ionic_q_flush(q);
+				rxq->last_wdog_cycles = now;
+
+				delta = 2 * rxq->wdog_ms;
+				if (delta > IONIC_Q_WDOG_MAX_MS)
+					delta = IONIC_Q_WDOG_MAX_MS;
+
+				rxq->wdog_ms = delta;
+                       }
+               }
+	}
 }
 
 /*
-- 
2.17.1