[PATCH v2 3/3] can: grcan: Only use the napi poll budget for rx

From: Andreas Larsson
Date: Fri Apr 29 2022 - 04:47:29 EST


The previous split budget between tx and rx made it return not using the
entire budget but at the same time not having calling called
napi_complete. This sometimes led to the poll to not be called, and at
the same time having tx and rx interrupts disabled resulting in the
driver getting stuck.

Fixes: 6cec9b07fe6a ("can: grcan: Add device driver for GRCAN and GRHCAN cores")

Signed-off-by: Andreas Larsson <andreas@xxxxxxxxxxx>
---
drivers/net/can/grcan.c | 22 +++++++---------------
1 file changed, 7 insertions(+), 15 deletions(-)

diff --git a/drivers/net/can/grcan.c b/drivers/net/can/grcan.c
index 2f56d4bbb65c..cb98eadc3b93 100644
--- a/drivers/net/can/grcan.c
+++ b/drivers/net/can/grcan.c
@@ -1124,7 +1124,7 @@ static int grcan_close(struct net_device *dev)
return 0;
}

-static int grcan_transmit_catch_up(struct net_device *dev, int budget)
+static void grcan_transmit_catch_up(struct net_device *dev)
{
struct grcan_priv *priv = netdev_priv(dev);
unsigned long flags;
@@ -1132,7 +1132,7 @@ static int grcan_transmit_catch_up(struct net_device *dev, int budget)

spin_lock_irqsave(&priv->lock, flags);

- work_done = catch_up_echo_skb(dev, budget, true);
+ work_done = catch_up_echo_skb(dev, -1, true);
if (work_done) {
if (!priv->resetting && !priv->closing &&
!(priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY))
@@ -1146,8 +1146,6 @@ static int grcan_transmit_catch_up(struct net_device *dev, int budget)
}

spin_unlock_irqrestore(&priv->lock, flags);
-
- return work_done;
}

static int grcan_receive(struct net_device *dev, int budget)
@@ -1229,19 +1227,13 @@ static int grcan_poll(struct napi_struct *napi, int budget)
struct net_device *dev = priv->dev;
struct grcan_registers __iomem *regs = priv->regs;
unsigned long flags;
- int tx_work_done, rx_work_done;
- int rx_budget = budget / 2;
- int tx_budget = budget - rx_budget;
+ int work_done;

- /* Half of the budget for receiving messages */
- rx_work_done = grcan_receive(dev, rx_budget);
+ work_done = grcan_receive(dev, budget);

- /* Half of the budget for transmitting messages as that can trigger echo
- * frames being received
- */
- tx_work_done = grcan_transmit_catch_up(dev, tx_budget);
+ grcan_transmit_catch_up(dev);

- if (rx_work_done < rx_budget && tx_work_done < tx_budget) {
+ if (work_done < budget) {
napi_complete(napi);

/* Guarantee no interference with a running reset that otherwise
@@ -1258,7 +1250,7 @@ static int grcan_poll(struct napi_struct *napi, int budget)
spin_unlock_irqrestore(&priv->lock, flags);
}

- return rx_work_done + tx_work_done;
+ return work_done;
}

/* Work tx bug by waiting while for the risky situation to clear. If that fails,
--
2.17.1