[1/1] net-next/hinic:optmize rx refill buffer mechanism
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Message ID 20181209191419.16845-1-xuechaojing@huawei.com
State Superseded
Commit e1a76515b0c20c3477200c1345c477cc0e68c4ad
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Series
  • [1/1] net-next/hinic:optmize rx refill buffer mechanism
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Commit Message

Xue Chaojing Dec. 9, 2018, 7:14 p.m. UTC
There is no need to schedule a different tasklet for refill,
This patch remove it.

Suggested-by: Neil Horman <nhorman@redhat.com>
Signed-off-by: Xue Chaojing <xuechaojing@huawei.com>
---
 drivers/net/ethernet/huawei/hinic/hinic_rx.c | 23 +++++---------------
 drivers/net/ethernet/huawei/hinic/hinic_rx.h |  2 --
 2 files changed, 5 insertions(+), 20 deletions(-)

Comments

David Miller Dec. 15, 2018, 7:31 p.m. UTC | #1
From: Xue Chaojing <xuechaojing@huawei.com>
Date: Sun, 9 Dec 2018 19:14:19 +0000

> There is no need to schedule a different tasklet for refill,
> This patch remove it.
> 
> Suggested-by: Neil Horman <nhorman@redhat.com>
> Signed-off-by: Xue Chaojing <xuechaojing@huawei.com>

I completely agree with Neil's analysis.

You should never receive a packet if refilling the ring entry
resources fails.

It is so dangerous to allow the RX ring to reach an empty state,
not only does it mean that the device will stop receiving frames
but also this is probably one of the least tested conditions in
ring based networking designs and it proabably has bugs that hang
the chip and require a HW reset to recover from.

Patch
diff mbox series

diff --git a/drivers/net/ethernet/huawei/hinic/hinic_rx.c b/drivers/net/ethernet/huawei/hinic/hinic_rx.c
index f86f2e693224..0098b206e7e9 100644
--- a/drivers/net/ethernet/huawei/hinic/hinic_rx.c
+++ b/drivers/net/ethernet/huawei/hinic/hinic_rx.c
@@ -43,6 +43,7 @@ 
 #define RX_IRQ_NO_LLI_TIMER             0
 #define RX_IRQ_NO_CREDIT                0
 #define RX_IRQ_NO_RESEND_TIMER          0
+#define HINIC_RX_BUFFER_WRITE           16
 
 /**
  * hinic_rxq_clean_stats - Clean the statistics of specific queue
@@ -229,7 +230,6 @@  static int rx_alloc_pkts(struct hinic_rxq *rxq)
 		wmb();  /* write all the wqes before update PI */
 
 		hinic_rq_update(rxq->rq, prod_idx);
-		tasklet_schedule(&rxq->rx_task);
 	}
 
 	return i;
@@ -258,17 +258,6 @@  static void free_all_rx_skbs(struct hinic_rxq *rxq)
 	}
 }
 
-/**
- * rx_alloc_task - tasklet for queue allocation
- * @data: rx queue
- **/
-static void rx_alloc_task(unsigned long data)
-{
-	struct hinic_rxq *rxq = (struct hinic_rxq *)data;
-
-	(void)rx_alloc_pkts(rxq);
-}
-
 /**
  * rx_recv_jumbo_pkt - Rx handler for jumbo pkt
  * @rxq: rx queue
@@ -333,6 +322,7 @@  static int rxq_recv(struct hinic_rxq *rxq, int budget)
 	struct hinic_qp *qp = container_of(rxq->rq, struct hinic_qp, rq);
 	u64 pkt_len = 0, rx_bytes = 0;
 	struct hinic_rq_wqe *rq_wqe;
+	unsigned int free_wqebbs;
 	int num_wqes, pkts = 0;
 	struct hinic_sge sge;
 	struct sk_buff *skb;
@@ -376,8 +366,9 @@  static int rxq_recv(struct hinic_rxq *rxq, int budget)
 		rx_bytes += pkt_len;
 	}
 
-	if (pkts)
-		tasklet_schedule(&rxq->rx_task); /* rx_alloc_pkts */
+	free_wqebbs = hinic_get_rq_free_wqebbs(rxq->rq);
+	if (free_wqebbs > HINIC_RX_BUFFER_WRITE)
+		rx_alloc_pkts(rxq);
 
 	u64_stats_update_begin(&rxq->rxq_stats.syncp);
 	rxq->rxq_stats.pkts += pkts;
@@ -494,8 +485,6 @@  int hinic_init_rxq(struct hinic_rxq *rxq, struct hinic_rq *rq,
 
 	sprintf(rxq->irq_name, "hinic_rxq%d", qp->q_id);
 
-	tasklet_init(&rxq->rx_task, rx_alloc_task, (unsigned long)rxq);
-
 	pkts = rx_alloc_pkts(rxq);
 	if (!pkts) {
 		err = -ENOMEM;
@@ -512,7 +501,6 @@  int hinic_init_rxq(struct hinic_rxq *rxq, struct hinic_rq *rq,
 
 err_req_rx_irq:
 err_rx_pkts:
-	tasklet_kill(&rxq->rx_task);
 	free_all_rx_skbs(rxq);
 	devm_kfree(&netdev->dev, rxq->irq_name);
 	return err;
@@ -528,7 +516,6 @@  void hinic_clean_rxq(struct hinic_rxq *rxq)
 
 	rx_free_irq(rxq);
 
-	tasklet_kill(&rxq->rx_task);
 	free_all_rx_skbs(rxq);
 	devm_kfree(&netdev->dev, rxq->irq_name);
 }
diff --git a/drivers/net/ethernet/huawei/hinic/hinic_rx.h b/drivers/net/ethernet/huawei/hinic/hinic_rx.h
index ab3fabab91b2..f8ed3fa6c8ee 100644
--- a/drivers/net/ethernet/huawei/hinic/hinic_rx.h
+++ b/drivers/net/ethernet/huawei/hinic/hinic_rx.h
@@ -42,8 +42,6 @@  struct hinic_rxq {
 
 	char                    *irq_name;
 
-	struct tasklet_struct   rx_task;
-
 	struct napi_struct      napi;
 };