[PATCH] ethtool: tsinfo: release net_device reference in ethnl_tsinfo_start()
From: Hui Peng <hidden>
Date: 2026-09-19 20:48:06
Also in:
lkml
Subsystem:
networking [ethtool], networking [general], the rest · Maintainers:
Andrew Lunn, Jakub Kicinski, "David S. Miller", Eric Dumazet, Paolo Abeni, Linus Torvalds
Unlike ethnl_default_start(), ethnl_tsinfo_start() keeps the net_device
reference acquired by ethnl_parse_header_dev_get() in
ctx->req_info->base.dev until ethnl_tsinfo_done().
When a Netlink dump (NLM_F_DUMP) of ETHTOOL_MSG_TSINFO_GET specifying a
device header fails on its initial netlink_dump() invocation (for
example, with -ENOBUFS when sk_rmem_alloc >= sk_rcvbuf), Netlink keeps
cb->cb_running = true without calling cb->done(). As long as the Netlink
socket remains open, the netdev_hold() reference is held, causing
unregister_netdevice() to hang indefinitely when the device is removed.
Save dev->ifindex in ctx->pos_ifindex with ctx->single_dev = true and
immediately release req_info->base.dev via ethnl_parse_header_dev_put()
in ethnl_tsinfo_start(), looking up the device transiently by ifindex
inside ethnl_tsinfo_dumpit().
Fixes: b9e3f7dc9ed9 ("net: ethtool: tsinfo: Enhance tsinfo to support several hwtstamp by net topology")
Assisted-by: LLM
Signed-off-by: Hui Peng <redacted>
---diff --git a/net/ethtool/tsinfo.c b/net/ethtool/tsinfo.c
--- a/net/ethtool/tsinfo.c
+++ b/net/ethtool/tsinfo.c@@ -295,6 +295,7 @@ struct ethnl_tsinfo_dump_ctx { struct tsinfo_reply_data *reply_data; unsigned long pos_ifindex; bool netdev_dump_done; + bool single_dev; unsigned long pos_phyindex; enum hwtstamp_provider_qualifier pos_phcqualifier; };
@@ -476,12 +477,15 @@ int ethnl_tsinfo_dumpit(struct sk_buff *skb, struct netlink_callback *cb) struct net *net = sock_net(skb->sk); int ret = 0; - if (ctx->req_info->base.dev) { - struct net_device *dev = ctx->req_info->base.dev; + if (ctx->single_dev) { + struct net_device *dev = dev_get_by_index(net, ctx->pos_ifindex); + if (!dev) + return -ENODEV; netdev_lock_ops_compat(dev); ret = ethnl_tsinfo_dump_one_net_topo(skb, dev, cb); netdev_unlock_ops_compat(dev); + dev_put(dev); return ret; }
@@ -533,6 +537,13 @@ int ethnl_tsinfo_start(struct netlink_callback *cb) ctx->req_info = req_info; ctx->reply_data = reply_data; ctx->pos_ifindex = 0; + ctx->single_dev = false; + if (req_info->base.dev) { + ctx->pos_ifindex = req_info->base.dev->ifindex; + ctx->single_dev = true; + ethnl_parse_header_dev_put(&req_info->base); + req_info->base.dev = NULL; + } ctx->pos_phyindex = 0; ctx->netdev_dump_done = false; ctx->pos_phcqualifier = HWTSTAMP_PROVIDER_QUALIFIER_PRECISE;
--
2.43.0