netdev - Re: [PATCH net v2] net: sfc: add missing xdp queue reinitialization

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Message-ID: <20220401110606.whyr5hnesb4ya67q@gmail.com>
Date:   Fri, 1 Apr 2022 12:06:06 +0100
From:   Martin Habets <habetsm.xilinx@...il.com>
To:     Taehee Yoo <ap420073@...il.com>
Cc:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        ecree.xilinx@...il.com, ast@...nel.org, daniel@...earbox.net,
        hawk@...nel.org, john.fastabend@...il.com, habetsm.xilinx@...il.com
Subject: Re: [PATCH net v2] net: sfc: add missing xdp queue reinitialization

Hi Taehee,

Thanks for looking into this. Unfortunately efx_realloc_channels()
has turned out to be quite fragile over the years, so I'm
keen to remove it in stead of patching it up all the time.

Could you try the patch below please?
If it works ok for you as well we'll be able to remove
efx_realloc_channels(). The added advantage of this approach
is that the netdev notifiers get informed of the change.

Regards,
Martin Habets <habetsm.xilinx@...il.com>

---
 drivers/net/ethernet/sfc/ethtool.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/sfc/ethtool.c b/drivers/net/ethernet/sfc/ethtool.c
index 48506373721a..8cfbe61737bb 100644
--- a/drivers/net/ethernet/sfc/ethtool.c
+++ b/drivers/net/ethernet/sfc/ethtool.c
@@ -179,6 +179,7 @@ efx_ethtool_set_ringparam(struct net_device *net_dev,
 {
 	struct efx_nic *efx = netdev_priv(net_dev);
 	u32 txq_entries;
+	int rc = 0;
 
 	if (ring->rx_mini_pending || ring->rx_jumbo_pending ||
 	    ring->rx_pending > EFX_MAX_DMAQ_SIZE ||
@@ -198,7 +199,17 @@ efx_ethtool_set_ringparam(struct net_device *net_dev,
 			   "increasing TX queue size to minimum of %u\n",
 			   txq_entries);
 
-	return efx_realloc_channels(efx, ring->rx_pending, txq_entries);
+	/* Apply the new settings */
+	efx->rxq_entries = ring->rx_pending;
+	efx->txq_entries = ring->tx_pending;
+
+	/* Update the datapath with the new settings if the interface is up */
+	if (!efx_check_disabled(efx) && netif_running(efx->net_dev)) {
+		dev_close(net_dev);
+		rc = dev_open(net_dev, NULL);
+	}
+
+	return rc;
 }
 
 static void efx_ethtool_get_wol(struct net_device *net_dev,