diff mbox series

[RFC,v2,net-next,06/15] net: mscc: ocelot: only drain extraction queue on error

Message ID 20201222134439.2478449-7-vladimir.oltean@nxp.com
State New
Headers show
Series [RFC,v2,net-next,01/15] net: dsa: tag_8021q: add helpers to deduce whether a VLAN ID is RX or TX VLAN | expand

Commit Message

Vladimir Oltean Dec. 22, 2020, 1:44 p.m. UTC 
It appears that the intention of this snippet of code is to not exit
ocelot_xtr_irq_handler() while in the middle of extracting a frame.
The problem in extracting it word by word is that future extraction
attempts are really easy to get desynchronized, since the IRQ handler
assumes that the first 16 bytes are the IFH, which give further
information about the frame, such as frame length.

But during normal operation, "err" will not be 0, but 4, set from here:

		for (i = 0; i < OCELOT_TAG_LEN / 4; i++) {
			err = ocelot_rx_frame_word(ocelot, grp, true, &ifh[i]);
			if (err != 4)
				break;
		}

		if (err != 4)
			break;

In that case, draining the extraction queue is a no-op. So explicitly
make this code execute only on negative err.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
Changes in v2:
Patch is new.

 drivers/net/ethernet/mscc/ocelot_vsc7514.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/mscc/ocelot_vsc7514.c b/drivers/net/ethernet/mscc/ocelot_vsc7514.c
index 00c6d9838970..ed632dd79245 100644
--- a/drivers/net/ethernet/mscc/ocelot_vsc7514.c
+++ b/drivers/net/ethernet/mscc/ocelot_vsc7514.c
@@ -702,7 +702,7 @@  static irqreturn_t ocelot_xtr_irq_handler(int irq, void *arg)
 		dev->stats.rx_packets++;
 	}
 
-	if (err)
+	if (err < 0)
 		while (ocelot_read(ocelot, QS_XTR_DATA_PRESENT) & BIT(grp))
 			ocelot_read_rix(ocelot, QS_XTR_RD, grp);