From nobody Sun Oct 5 20:15:23 2025 Received: from smtp.cecloud.com (smtp-pop-umt-1.cecloud.com [1.203.97.246]) by smtp.subspace.kernel.org (Postfix) with ESMTP id D3B1926D4F9; Wed, 30 Jul 2025 09:36:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=1.203.97.246 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753868225; cv=none; b=SeXg88cveorO4tfSiAOCZGLRInpmDDoXIQ/4nvhFFnVLqZ6xV9KRrBE6oz7P8MxK//8efNSceMVWVBX71BXYLuZSORDTNnm8UgupNnpGS0Mds7jxKNdhVQNDBnkFybTNK9h+T2jVSavesd2454Q5Tjo5mvOPMKtjkoGgZ2qvjuA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753868225; c=relaxed/simple; bh=XgY84VYmd2hH14+kEb5sOVSlwxb483gjmX4Ox29snQU=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=j/zvh2nwVe3JGYFh/o3SMSYVGhN8u5XurJNJhghPE4jkjCMkXyl1yWQTPqBtnN+P6lz1XS+Laq8beT75kAxLT/VTSvWzrniJNbpDCttrxXoYOb0TrB/n/cc8qZZZBqDn6KDylKaVL2D5F/QeR5Nx9GGrooAKwsPMlbI/Er4OMYc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=cestc.cn; spf=pass smtp.mailfrom=cestc.cn; arc=none smtp.client-ip=1.203.97.246 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=cestc.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=cestc.cn Received: from localhost (localhost [127.0.0.1]) by smtp.cecloud.com (Postfix) with ESMTP id 933C17C015E; Wed, 30 Jul 2025 17:29:52 +0800 (CST) X-MAIL-GRAY: 0 X-MAIL-DELIVERY: 1 X-SKE-CHECKED: 1 X-ANTISPAM-LEVEL: 2 Received: from localhost.localdomain (unknown [111.48.58.13]) by smtp.cecloud.com (postfix) whith ESMTP id P2727722T281471814136176S1753867787395864_; Wed, 30 Jul 2025 17:29:52 +0800 (CST) X-IP-DOMAINF: 1 X-RL-SENDER: zhangyanjun@cestc.cn X-SENDER: zhangyanjun@cestc.cn X-LOGIN-NAME: zhangyanjun@cestc.cn X-FST-TO: willemdebruijn.kernel@gmail.com X-RCPT-COUNT: 5 X-LOCAL-RCPT-COUNT: 1 X-MUTI-DOMAIN-COUNT: 0 X-SENDER-IP: 111.48.58.13 X-ATTACHMENT-NUM: 0 X-UNIQUE-TAG: X-System-Flag: 0 From: zhangyanjun@cestc.cn To: willemdebruijn.kernel@gmail.com, jasowang@redhat.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, zhangyanjun@cestc.cn Subject: [PATCH] tap/tun: add stats accounting when failed to transfer data to user Date: Wed, 30 Jul 2025 17:29:40 +0800 Message-Id: <20250730092940.1439637-1-zhangyanjun@cestc.cn> X-Mailer: git-send-email 2.31.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Yanjun Zhang To more accurately detect packet dropped, we add the dropped packet counter with the device when kfree_skb is called because of failing to transfer data to user space. Signed-off-by: Yanjun Zhang --- drivers/net/tap.c | 14 +++++++++++--- drivers/net/tun.c | 9 ++++++--- 2 files changed, 17 insertions(+), 6 deletions(-) diff --git a/drivers/net/tap.c b/drivers/net/tap.c index bdf0788d8..9d288a1ad 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -759,6 +759,8 @@ static ssize_t tap_do_read(struct tap_queue *q, { DEFINE_WAIT(wait); ssize_t ret =3D 0; + struct tap_dev *tap; + enum skb_drop_reason drop_reason =3D SKB_DROP_REASON_NOT_SPECIFIED; =20 if (!iov_iter_count(to)) { kfree_skb(skb); @@ -794,10 +796,16 @@ static ssize_t tap_do_read(struct tap_queue *q, put: if (skb) { ret =3D tap_put_user(q, skb, to); - if (unlikely(ret < 0)) - kfree_skb(skb); - else + if (unlikely(ret < 0)) { + kfree_skb_reason(skb, drop_reason); + rcu_read_lock(); + tap =3D rcu_dereference(q->tap); + if (tap && tap->count_rx_dropped) + tap->count_rx_dropped(tap); + rcu_read_unlock(); + } else { consume_skb(skb); + } } return ret; } diff --git a/drivers/net/tun.c b/drivers/net/tun.c index f8c5e2fd0..eb3c68e5f 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -2137,6 +2137,7 @@ static ssize_t tun_do_read(struct tun_struct *tun, st= ruct tun_file *tfile, { ssize_t ret; int err; + enum skb_drop_reason drop_reason =3D SKB_DROP_REASON_NOT_SPECIFIED; =20 if (!iov_iter_count(to)) { tun_ptr_free(ptr); @@ -2159,10 +2160,12 @@ static ssize_t tun_do_read(struct tun_struct *tun, = struct tun_file *tfile, struct sk_buff *skb =3D ptr; =20 ret =3D tun_put_user(tun, tfile, skb, to); - if (unlikely(ret < 0)) - kfree_skb(skb); - else + if (unlikely(ret < 0)) { + dev_core_stats_tx_dropped_inc(tun->dev); + kfree_skb_reason(skb, drop_reason); + } else { consume_skb(skb); + } } =20 return ret; --=20 2.31.1