[Intel-wired-lan] [PATCH net] igc: Clear old XDP info when changing ring settings

[Intel-wired-lan] [PATCH net] igc: Clear old XDP info when changing ring settings

[Kurt Kanzenbach]

When changing ring sizes the driver triggers kernel warnings in XDP code.

For instance, running 'ethtool -G $interface tx 1024 rx 1024' yields:

|[  754.838136] Missing unregister, handled but fix driver
|[  754.838143] WARNING: CPU: 4 PID: 704 at net/core/xdp.c:170 xdp_rxq_info_reg+0x7d/0xe0

The newly allocated ring is copied by memcpy() and still contains the old XDP
information. Therefore, it has to be cleared before allocating new resources
by igc_setup_rx_resources().

Igb does it the same way. Keep the code in sync.

Fixes: 4609ffb9f615 ("igc: Refactor XDP rxq info registration")
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
---
 drivers/net/ethernet/intel/igc/igc_ethtool.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/intel/igc/igc_ethtool.c b/drivers/net/ethernet/intel/igc/igc_ethtool.c
index 8cc077b712ad..93839106504d 100644
--- a/drivers/net/ethernet/intel/igc/igc_ethtool.c
+++ b/drivers/net/ethernet/intel/igc/igc_ethtool.c
@@ -671,6 +671,10 @@ igc_ethtool_set_ringparam(struct net_device *netdev,
 			memcpy(&temp_ring[i], adapter->rx_ring[i],
 			       sizeof(struct igc_ring));
 
+			/* Clear copied XDP RX-queue info */
+			memset(&temp_ring[i].xdp_rxq, 0,
+			       sizeof(temp_ring[i].xdp_rxq));
+
 			temp_ring[i].count = new_rx_count;
 			err = igc_setup_rx_resources(&temp_ring[i]);
 			if (err) {
-- 
2.30.2

[Intel-wired-lan] [PATCH net] igc: Clear old XDP info when changing ring settings

[Nguyen, Anthony L]

Hi Kurt,

On Fri, 2022-02-04 at 09:02 +0100, Kurt Kanzenbach wrote:
> When changing ring sizes the driver triggers kernel warnings in XDP
> code.
> 
> For instance, running 'ethtool -G $interface tx 1024 rx 1024' yields:
> 
> > [? 754.838136] Missing unregister, handled but fix driver
> > [? 754.838143] WARNING: CPU: 4 PID: 704 at net/core/xdp.c:170
> > xdp_rxq_info_reg+0x7d/0xe0
> 
> The newly allocated ring is copied by memcpy() and still contains the
> old XDP
> information. Therefore, it has to be cleared before allocating new
> resources
> by igc_setup_rx_resources().
> 
> Igb does it the same way. Keep the code in sync.

Thanks for the patch, but we have a patch[1] to resolve this issue in a
more preferred method. igb is actually changing as well to this new
solution [2].

Thanks,
Tony

[1] https://patchwork.ozlabs.org/patch/1581816/
[2] https://patchwork.ozlabs.org/patch/1581815/

> Fixes: 4609ffb9f615 ("igc: Refactor XDP rxq info registration")
> Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>

[Intel-wired-lan] [PATCH net] igc: Clear old XDP info when changing ring settings

[Kurt Kanzenbach]

On Fri Feb 04 2022, Anthony L. Nguyen wrote:
> Thanks for the patch, but we have a patch[1] to resolve this issue in a
> more preferred method. igb is actually changing as well to this new
> solution [2].

OK, great.

Thanks,
Kurt
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