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can: mscan: mscan_rx_poll(): fix rx path lockup when returning from polling to irq mode 

commit 2d77bd61a2 upstream.

Under load, the RX side of the mscan driver can get stuck while TX still
works. Restarting the interface locks up the system. This behaviour
could be reproduced reliably on a MPC5121e based system.

The patch fixes the return value of the NAPI polling function (should be
the number of processed packets, not constant 1) and the condition under
which IRQs are enabled again after polling is finished.

With this patch, no more lockups were observed over a test period of ten
days.

Fixes: afa17a500a ("net/can: add driver for mscan family & mpc52xx_mscan")
Signed-off-by: Florian Faber <faber@faberman.de>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Florian Faber 2019-12-26 19:51:24 +01:00 committed by Greg Kroah-Hartman
parent 1ad3ee211d
commit 584b8299f7
1 changed files with 10 additions and 11 deletions
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21
drivers/net/can/mscan/mscan.c
View File

@ -381,13 +381,12 @@ static int mscan_rx_poll(struct napi_struct *napi, int quota)
struct net_device *dev = napi->dev;
struct mscan_regs __iomem *regs = priv->reg_base;
struct net_device_stats *stats = &dev->stats;
int npackets = 0;
int ret = 1;
int work_done = 0;
struct sk_buff *skb;
struct can_frame *frame;
u8 canrflg;
while (npackets < quota) {
while (work_done < quota) {
canrflg = in_8(&regs->canrflg);
if (!(canrflg & (MSCAN_RXF | MSCAN_ERR_IF)))
break;
@ -408,18 +407,18 @@ static int mscan_rx_poll(struct napi_struct *napi, int quota)
stats->rx_packets++;
stats->rx_bytes += frame->can_dlc;
npackets++;
work_done++;
netif_receive_skb(skb);
}
if (!(in_8(&regs->canrflg) & (MSCAN_RXF | MSCAN_ERR_IF))) {
napi_complete(&priv->napi);
clear_bit(F_RX_PROGRESS, &priv->flags);
if (priv->can.state < CAN_STATE_BUS_OFF)
out_8(&regs->canrier, priv->shadow_canrier);
ret = 0;
if (work_done < quota) {
if (likely(napi_complete_done(&priv->napi, work_done))) {
clear_bit(F_RX_PROGRESS, &priv->flags);
if (priv->can.state < CAN_STATE_BUS_OFF)
out_8(&regs->canrier, priv->shadow_canrier);
}
}
return ret;
return work_done;
}
static irqreturn_t mscan_isr(int irq, void *dev_id)