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Subject[PATCH 3.4 11/39] can: c_can: Fix RX message handling, handle lost message before EOB
Date
3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Markus Pargmann <mpa@pengutronix.de>

commit 5d0f801a2ccec3b1fdabc3392c8d99ed0413d216 upstream.

If we handle end of block messages with higher priority than a lost message,
we can run into an endless interrupt loop.

This is reproducable with a am335x processor and "cansequence -r" at 1Mbit.
As soon as we loose a packet we can't escape from an interrupt loop.

This patch fixes the problem by handling lost packets before EOB packets.

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/can/c_can/c_can.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -760,9 +760,6 @@ static int c_can_do_rx_poll(struct net_d
msg_ctrl_save = priv->read_reg(priv,
&priv->regs->ifregs[0].msg_cntrl);

- if (msg_ctrl_save & IF_MCONT_EOB)
- return num_rx_pkts;
-
if (msg_ctrl_save & IF_MCONT_MSGLST) {
c_can_handle_lost_msg_obj(dev, 0, msg_obj);
num_rx_pkts++;
@@ -770,6 +767,9 @@ static int c_can_do_rx_poll(struct net_d
continue;
}

+ if (msg_ctrl_save & IF_MCONT_EOB)
+ return num_rx_pkts;
+
if (!(msg_ctrl_save & IF_MCONT_NEWDAT))
continue;




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