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The pair of functions, * skb_clone_tx_timestamp() * skb_complete_tx_timestamp() were designed to allow timestamping in PHY devices. The first function, called during the MAC driver's hard_xmit method, identifies PTP protocol packets, clones them, and gives them to the PHY device driver. The PHY driver may hold onto the packet and deliver it at a later time using the second function, which adds the packet to the socket's error queue. As pointed out by Johannes, nothing prevents the socket from disappearing while the cloned packet is sitting in the PHY driver awaiting a timestamp. This patch fixes the issue by taking a reference on the socket for each such packet. In addition, the comments regarding the usage of these function are expanded to highlight the rule that PHY drivers must use skb_complete_tx_timestamp() to release the packet, in order to release the socket reference, too. These functions first appeared in v2.6.36. Reported-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Richard Cochran <richard.cochran@omicron.at> Cc: <stable@vger.kernel.org> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Reviewed-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: David S. Miller <davem@davemloft.net>
139 lines
3.1 KiB
C
139 lines
3.1 KiB
C
/*
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* PTP 1588 clock support - support for timestamping in PHY devices
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*
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* Copyright (C) 2010 OMICRON electronics GmbH
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/errqueue.h>
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#include <linux/phy.h>
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#include <linux/ptp_classify.h>
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#include <linux/skbuff.h>
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static struct sock_filter ptp_filter[] = {
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PTP_FILTER
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};
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static unsigned int classify(const struct sk_buff *skb)
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{
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if (likely(skb->dev &&
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skb->dev->phydev &&
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skb->dev->phydev->drv))
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return sk_run_filter(skb, ptp_filter);
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else
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return PTP_CLASS_NONE;
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}
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void skb_clone_tx_timestamp(struct sk_buff *skb)
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{
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struct phy_device *phydev;
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struct sk_buff *clone;
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struct sock *sk = skb->sk;
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unsigned int type;
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if (!sk)
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return;
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type = classify(skb);
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switch (type) {
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case PTP_CLASS_V1_IPV4:
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case PTP_CLASS_V1_IPV6:
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case PTP_CLASS_V2_IPV4:
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case PTP_CLASS_V2_IPV6:
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case PTP_CLASS_V2_L2:
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case PTP_CLASS_V2_VLAN:
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phydev = skb->dev->phydev;
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if (likely(phydev->drv->txtstamp)) {
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if (!atomic_inc_not_zero(&sk->sk_refcnt))
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return;
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clone = skb_clone(skb, GFP_ATOMIC);
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if (!clone) {
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sock_put(sk);
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return;
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}
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clone->sk = sk;
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phydev->drv->txtstamp(phydev, clone, type);
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}
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break;
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default:
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break;
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}
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}
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EXPORT_SYMBOL_GPL(skb_clone_tx_timestamp);
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void skb_complete_tx_timestamp(struct sk_buff *skb,
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struct skb_shared_hwtstamps *hwtstamps)
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{
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struct sock *sk = skb->sk;
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struct sock_exterr_skb *serr;
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int err;
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if (!hwtstamps) {
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sock_put(sk);
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kfree_skb(skb);
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return;
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}
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*skb_hwtstamps(skb) = *hwtstamps;
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serr = SKB_EXT_ERR(skb);
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memset(serr, 0, sizeof(*serr));
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serr->ee.ee_errno = ENOMSG;
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serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
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skb->sk = NULL;
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err = sock_queue_err_skb(sk, skb);
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sock_put(sk);
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if (err)
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kfree_skb(skb);
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}
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EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
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bool skb_defer_rx_timestamp(struct sk_buff *skb)
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{
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struct phy_device *phydev;
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unsigned int type;
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if (skb_headroom(skb) < ETH_HLEN)
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return false;
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__skb_push(skb, ETH_HLEN);
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type = classify(skb);
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__skb_pull(skb, ETH_HLEN);
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switch (type) {
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case PTP_CLASS_V1_IPV4:
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case PTP_CLASS_V1_IPV6:
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case PTP_CLASS_V2_IPV4:
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case PTP_CLASS_V2_IPV6:
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case PTP_CLASS_V2_L2:
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case PTP_CLASS_V2_VLAN:
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phydev = skb->dev->phydev;
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if (likely(phydev->drv->rxtstamp))
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return phydev->drv->rxtstamp(phydev, skb, type);
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break;
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default:
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break;
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}
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return false;
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}
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EXPORT_SYMBOL_GPL(skb_defer_rx_timestamp);
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void __init skb_timestamping_init(void)
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{
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BUG_ON(sk_chk_filter(ptp_filter, ARRAY_SIZE(ptp_filter)));
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}
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