diff mbox series

[v4,net-next,09/16] net: mscc: ocelot: only drain extraction queue on error

Message ID 20210119230749.1178874-10-olteanv@gmail.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series tag_8021q for Ocelot switches | expand

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netdev/fixes_present success Link
netdev/patch_count fail Series longer than 15 patches
netdev/tree_selection success Clearly marked for net-next
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netdev/cc_maintainers success CCed 7 of 7 maintainers
netdev/source_inline success Was 0 now: 0
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netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
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netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 8 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Vladimir Oltean Jan. 19, 2021, 11:07 p.m. UTC 
From: Vladimir Oltean <vladimir.oltean@nxp.com>

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 v4:
None.

Changes in v3:
None.

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 5140639910a6..49089a014dda 100644
--- a/drivers/net/ethernet/mscc/ocelot_vsc7514.c
+++ b/drivers/net/ethernet/mscc/ocelot_vsc7514.c
@@ -701,7 +701,7 @@  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);