[PATCH 5.4 07/18] can: grcan: only use the NAPI poll budget for RX

Greg Kroah-Hartman
2022-05-13T14:31:30Z

From: Andreas Larsson <andreas@gaisler.com>

commit 2873d4d52f7c52d60b316ba6c47bd7122b5a9861 upstream.

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")
Link: https://lore.kernel.org/all/20220429084656.29788-4-andreas@gaisler.com
Cc: stable@vger.kernel.org
Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/can/grcan.c | 22 +++++++---------------
1 file changed, 7 insertions(+), 15 deletions(-)

--- a/drivers/net/can/grcan.c
+++ b/drivers/net/can/grcan.c
@@ -1137,7 +1137,7 @@ static int grcan_close(struct net_device
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;
@@ -1145,7 +1145,7 @@ static int grcan_transmit_catch_up(struc

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))
@@ -1159,8 +1159,6 @@ static int grcan_transmit_catch_up(struc
}

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

static int grcan_receive(struct net_device *dev, int budget)
@@ -1242,19 +1240,13 @@ static int grcan_poll(struct napi_struct
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 receiveing 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
@@ -1271,7 +1263,7 @@ static int grcan_poll(struct napi_struct
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,