From: Jakub Kicinski <kuba@kernel.org>
Date: Fri, 13 Dec 2024 15:22:40 +0000 (-0800)
Subject: netdev: fix repeated netlink messages in queue dump
X-Git-Tag: v6.12.7~115
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d924c8afe666b159c214f4c1e689f39d2c16aa0a;p=thirdparty%2Fkernel%2Fstable.git

netdev: fix repeated netlink messages in queue dump

[ Upstream commit b1f3a2f5a742c1e939a73031bd31b9e557a2d77d ]

The context is supposed to record the next queue to dump,
not last dumped. If the dump doesn't fit we will restart
from the already-dumped queue, duplicating the message.

Before this fix and with the selftest improvements later
in this series we see:

  # ./run_kselftest.sh -t drivers/net:queues.py
  timeout set to 45
  selftests: drivers/net: queues.py
  KTAP version 1
  1..2
  # Check| At /root/ksft-net-drv/drivers/net/./queues.py, line 32, in get_queues:
  # Check|     ksft_eq(queues, expected)
  # Check failed 102 != 100
  # Check| At /root/ksft-net-drv/drivers/net/./queues.py, line 32, in get_queues:
  # Check|     ksft_eq(queues, expected)
  # Check failed 101 != 100
  not ok 1 queues.get_queues
  ok 2 queues.addremove_queues
  # Totals: pass:1 fail:1 xfail:0 xpass:0 skip:0 error:0
  not ok 1 selftests: drivers/net: queues.py # exit=1

With the fix:

  # ./ksft-net-drv/run_kselftest.sh -t drivers/net:queues.py
  timeout set to 45
  selftests: drivers/net: queues.py
  KTAP version 1
  1..2
  ok 1 queues.get_queues
  ok 2 queues.addremove_queues
  # Totals: pass:2 fail:0 xfail:0 xpass:0 skip:0 error:0

Fixes: 6b6171db7fc8 ("netdev-genl: Add netlink framework functions for queue")
Reviewed-by: Joe Damato <jdamato@fastly.com>
Link: https://patch.msgid.link/20241213152244.3080955-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index d2baa1af9df09..71359922ae8b9 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -417,24 +417,21 @@ netdev_nl_queue_dump_one(struct net_device *netdev, struct sk_buff *rsp,
 			 struct netdev_nl_dump_ctx *ctx)
 {
 	int err = 0;
-	int i;
 
 	if (!(netdev->flags & IFF_UP))
 		return err;
 
-	for (i = ctx->rxq_idx; i < netdev->real_num_rx_queues;) {
-		err = netdev_nl_queue_fill_one(rsp, netdev, i,
+	for (; ctx->rxq_idx < netdev->real_num_rx_queues; ctx->rxq_idx++) {
+		err = netdev_nl_queue_fill_one(rsp, netdev, ctx->rxq_idx,
 					       NETDEV_QUEUE_TYPE_RX, info);
 		if (err)
 			return err;
-		ctx->rxq_idx = i++;
 	}
-	for (i = ctx->txq_idx; i < netdev->real_num_tx_queues;) {
-		err = netdev_nl_queue_fill_one(rsp, netdev, i,
+	for (; ctx->txq_idx < netdev->real_num_tx_queues; ctx->txq_idx++) {
+		err = netdev_nl_queue_fill_one(rsp, netdev, ctx->txq_idx,
 					       NETDEV_QUEUE_TYPE_TX, info);
 		if (err)
 			return err;
-		ctx->txq_idx = i++;
 	}
 
 	return err;