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[34.83.123.78]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-877a95f915csm1282928b3a.29.2026.09.19.13.48.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 19 Sep 2026 13:48:05 -0700 (PDT) From: Hui Peng To: Andrew Lunn , Jakub Kicinski Cc: "David S . Miller" , Eric Dumazet , Paolo Abeni , Kory Maincent , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] ethtool: tsinfo: release net_device reference in ethnl_tsinfo_start() Date: Sat, 19 Sep 2026 20:48:03 +0000 Message-ID: <20260919204803.2811673-1-benquike@gmail.com> X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- 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