From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F34A14119F8; Thu, 30 Jul 2026 14:58:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785423536; cv=none; b=DhOtwZam9VG2BP+rv37B0MMGFVY++iwx6d7qfL6Rq1F0M/NKYq9TVZqWlPPtlHMBl+FwKjQtcFTYAqm6aO4efjniPWG/25H0ZOJjNEvfYTsMoWxTWhPz+MbpKU2ytdmRkhgjg731MmtTGvpoDYFAeOLYhHqw+UgaeEgx32FlkDQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785423536; c=relaxed/simple; bh=y+LjNubACOPtuiYRaE2v9BAB8s35YJVFY3tg8tKPG3U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hQJSe6HkIGuVAUex24fyaJhEWnaKYmLLXiyU6LoXQ3OWu/qPlVfwu09+7x4aRQgJzcSipV/CszLDZCaypBH49zDvTYXUJzt9IPiJ0SKWlvbll+goSlN/WMV6xKDyBSMheDmjbCwww2rs83Zu9FNX5mhAfE6XAo+kNjRqTrcc6Oc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=2GvT76Gf; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="2GvT76Gf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A3FC1F000E9; Thu, 30 Jul 2026 14:58:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785423534; bh=xxeekYy7shK8NPbsUqNpl4irMUslTEXrohtYbU9uby4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=2GvT76GfkcQMztkgVr/61Ca5kVCFpCEhvfknIrSu+wu2sTCmpaIBjXSMNgCioPjrs WwmYhfL1NSGuhmoFlCMydZNAyPdE21VEDRpPzI72BX4DOfjltINN5S3TD9FGCb+4UV SJ9f+0nnTMVH7Zp/Pbdt2dDxvMYvsJvrCCrWQGAc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , Joe Damato , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18 034/675] net: plumb drop reasons to __dev_queue_xmit() Date: Thu, 30 Jul 2026 16:06:04 +0200 Message-ID: <20260730141445.846025887@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141445.110192266@linuxfoundation.org> References: <20260730141445.110192266@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 045f977dd4ebdd3ad8e96cf684917adfc5805adb ] Add drop reasons to __dev_queue_xmit(): - SKB_DROP_REASON_DEV_READY : device is not UP. - SKB_DROP_REASON_RECURSION_LIMIT : recursion limit on virtual device is hit. Also add an unlikely() for the SKB_DROP_REASON_DEV_READY case, and reduce indentation level. Signed-off-by: Eric Dumazet Reviewed-by: Joe Damato Link: https://patch.msgid.link/20260312201824.203093-3-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: 6860b467f569 ("xfrm: propagate -EINPROGRESS from validate_xmit_xfrm()") Signed-off-by: Sasha Levin --- net/core/dev.c | 83 ++++++++++++++++++++++++++------------------------ 1 file changed, 43 insertions(+), 40 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 8dee703a0916ed..246d654551ae56 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4702,9 +4702,10 @@ int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev) { struct net_device *dev = skb->dev; struct netdev_queue *txq = NULL; - struct Qdisc *q; - int rc = -ENOMEM; + enum skb_drop_reason reason; + int cpu, rc = -ENOMEM; bool again = false; + struct Qdisc *q; skb_reset_mac_header(skb); skb_assert_len(skb); @@ -4773,59 +4774,61 @@ int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev) * Check this and shot the lock. It is not prone from deadlocks. *Either shot noqueue qdisc, it is even simpler 8) */ - if (dev->flags & IFF_UP) { - int cpu = smp_processor_id(); /* ok because BHs are off */ + if (unlikely(!(dev->flags & IFF_UP))) { + reason = SKB_DROP_REASON_DEV_READY; + goto drop; + } - if (!netif_tx_owned(txq, cpu)) { - bool is_list = false; + cpu = smp_processor_id(); /* ok because BHs are off */ - if (dev_xmit_recursion()) - goto recursion_alert; + if (likely(!netif_tx_owned(txq, cpu))) { + bool is_list = false; - skb = validate_xmit_skb(skb, dev, &again); - if (!skb) - goto out; + if (dev_xmit_recursion()) + goto recursion_alert; - HARD_TX_LOCK(dev, txq, cpu); + skb = validate_xmit_skb(skb, dev, &again); + if (!skb) + goto out; - if (!netif_xmit_stopped(txq)) { - is_list = !!skb->next; + HARD_TX_LOCK(dev, txq, cpu); - dev_xmit_recursion_inc(); - skb = dev_hard_start_xmit(skb, dev, txq, &rc); - dev_xmit_recursion_dec(); + if (!netif_xmit_stopped(txq)) { + is_list = !!skb->next; - /* GSO segments a single SKB into - * a list of frames. TCP expects error - * to mean none of the data was sent. - */ - if (is_list) - rc = NETDEV_TX_OK; - } - HARD_TX_UNLOCK(dev, txq); - if (!skb) /* xmit completed */ - goto out; + dev_xmit_recursion_inc(); + skb = dev_hard_start_xmit(skb, dev, txq, &rc); + dev_xmit_recursion_dec(); - net_crit_ratelimited("Virtual device %s asks to queue packet!\n", - dev->name); - /* NETDEV_TX_BUSY or queue was stopped */ - if (!is_list) - rc = -ENETDOWN; - } else { - /* Recursion is detected! It is possible, - * unfortunately + /* GSO segments a single SKB into a list of frames. + * TCP expects error to mean none of the data was sent. */ -recursion_alert: - net_crit_ratelimited("Dead loop on virtual device %s, fix it urgently!\n", - dev->name); - rc = -ENETDOWN; + if (is_list) + rc = NETDEV_TX_OK; } + HARD_TX_UNLOCK(dev, txq); + if (!skb) /* xmit completed */ + goto out; + + net_crit_ratelimited("Virtual device %s asks to queue packet!\n", + dev->name); + /* NETDEV_TX_BUSY or queue was stopped */ + if (!is_list) + rc = -ENETDOWN; + } else { + /* Recursion is detected! It is possible unfortunately. */ +recursion_alert: + net_crit_ratelimited("Dead loop on virtual device %s, fix it urgently!\n", + dev->name); + rc = -ENETDOWN; } + reason = SKB_DROP_REASON_RECURSION_LIMIT; +drop: rcu_read_unlock_bh(); dev_core_stats_tx_dropped_inc(dev); - kfree_skb_list(skb); + kfree_skb_list_reason(skb, reason); return rc; out: rcu_read_unlock_bh(); -- 2.53.0