diff options
authorRichard Cochran <richardcochran@gmail.com>2011-10-21 00:49:15 +0000
committerGreg Kroah-Hartman <gregkh@suse.de>2011-11-11 09:43:08 -0800
commit6d06e8d0a5bcc13717291fe46303bfd32cfb9d7a (patch)
parentf9aea842ccd9be4c49e90c848afd187dd9880638 (diff)
net: hold sock reference while processing tx timestamps
commit da92b194cc36b5dc1fbd85206aeeffd80bee0c39 upstream. 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> 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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
3 files changed, 17 insertions, 4 deletions
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 54fc4138955..79f337c4738 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -420,7 +420,7 @@ struct phy_driver {
* Requests a Tx timestamp for 'skb'. The phy driver promises
- * to deliver it to the socket's error queue as soon as a
+ * to deliver it using skb_complete_tx_timestamp() as soon as a
* timestamp becomes available. One of the PTP_CLASS_ values
* is passed in 'type'.
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 8bd383caa36..0f966460a34 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2020,8 +2020,13 @@ static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
* skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
+ * PHY drivers may accept clones of transmitted packets for
+ * timestamping via their phy_driver.txtstamp method. These drivers
+ * must call this function to return the skb back to the stack, with
+ * or without a timestamp.
+ *
* @skb: clone of the the original outgoing packet
- * @hwtstamps: hardware time stamps
+ * @hwtstamps: hardware time stamps, may be NULL if not available
void skb_complete_tx_timestamp(struct sk_buff *skb,
diff --git a/net/core/timestamping.c b/net/core/timestamping.c
index 98a52640e7c..82fb28857b6 100644
--- a/net/core/timestamping.c
+++ b/net/core/timestamping.c
@@ -57,9 +57,13 @@ void skb_clone_tx_timestamp(struct sk_buff *skb)
phydev = skb->dev->phydev;
if (likely(phydev->drv->txtstamp)) {
+ if (!atomic_inc_not_zero(&sk->sk_refcnt))
+ return;
clone = skb_clone(skb, GFP_ATOMIC);
- if (!clone)
+ if (!clone) {
+ sock_put(sk);
+ }
clone->sk = sk;
phydev->drv->txtstamp(phydev, clone, type);
@@ -77,8 +81,11 @@ void skb_complete_tx_timestamp(struct sk_buff *skb,
struct sock_exterr_skb *serr;
int err;
- if (!hwtstamps)
+ if (!hwtstamps) {
+ sock_put(sk);
+ kfree_skb(skb);
+ }
*skb_hwtstamps(skb) = *hwtstamps;
serr = SKB_EXT_ERR(skb);
@@ -87,6 +94,7 @@ void skb_complete_tx_timestamp(struct sk_buff *skb,
serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
skb->sk = NULL;
err = sock_queue_err_skb(sk, skb);
+ sock_put(sk);
if (err)