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Date: Thu, 04 Sep 2014 10:48:58 -0700
From: Rick Jones <rick.jones2@...com>
To: Alexander Duyck <alexander.h.duyck@...el.com>,
netdev@...r.kernel.org
CC: richardcochran@...il.com, davem@...emloft.net, willemb@...gle.com
Subject: Re: [PATCH net-next v4 2/3] net-timestamp: Make the clone operation
stand-alone from phy timestamping
On 09/04/2014 10:31 AM, Alexander Duyck wrote:
>
> ---
>
> v2: Renamed function to skb_clone_sk.
> Added destructor to call sock_put instead of doing it ourselves.
> Dropped freeing functionality from skb_complete_tx_timestamp.
> Added additional documentation to the code.
>
> v3: Renamed destructor sock_efree and moved to sock.c/h
> Added sock_hold/sock_put around call to sock_queue_err_skb
>
> v4: Dropped combining sock_edemux with sock_efree where the 2 are identical
>
> drivers/net/phy/dp83640.c | 6 +++---
> include/linux/skbuff.h | 2 ++
> include/net/sock.h | 1 +
> net/core/skbuff.c | 32 +++++++++++++++++++++++++-------
> net/core/sock.c | 6 ++++++
> net/core/timestamping.c | 14 +++-----------
> 6 files changed, 40 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/net/phy/dp83640.c b/drivers/net/phy/dp83640.c
> index d5991ac..87648b3 100644
> --- a/drivers/net/phy/dp83640.c
> +++ b/drivers/net/phy/dp83640.c
> @@ -1148,7 +1148,7 @@ static void dp83640_remove(struct phy_device *phydev)
> kfree_skb(skb);
>
> while ((skb = skb_dequeue(&dp83640->tx_queue)) != NULL)
> - skb_complete_tx_timestamp(skb, NULL);
> + kfree_skb(skb);
I may not be following the flow correctly, and may be noticing only
because I just did two "floor-sweeping" patches to shift be2net and
mlx4_en to "consume" but would it be better if these kfree_skb calls
were a "consume" variety?
rick jones
>
> clock = dp83640_clock_get(dp83640->clock);
>
> @@ -1405,7 +1405,7 @@ static void dp83640_txtstamp(struct phy_device *phydev,
>
> case HWTSTAMP_TX_ONESTEP_SYNC:
> if (is_sync(skb, type)) {
> - skb_complete_tx_timestamp(skb, NULL);
> + kfree_skb(skb);
> return;
> }
> /* fall through */
> @@ -1416,7 +1416,7 @@ static void dp83640_txtstamp(struct phy_device *phydev,
>
> case HWTSTAMP_TX_OFF:
> default:
> - skb_complete_tx_timestamp(skb, NULL);
> + kfree_skb(skb);
> break;
> }
> }
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 02529fc..1cf0cfa 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -2690,6 +2690,8 @@ static inline ktime_t net_invalid_timestamp(void)
> return ktime_set(0, 0);
> }
>
> +struct sk_buff *skb_clone_sk(struct sk_buff *skb);
> +
> #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
>
> void skb_clone_tx_timestamp(struct sk_buff *skb);
> diff --git a/include/net/sock.h b/include/net/sock.h
> index 3fde613..e02be37 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -1574,6 +1574,7 @@ struct sk_buff *sock_wmalloc(struct sock *sk, unsigned long size, int force,
> void sock_wfree(struct sk_buff *skb);
> void skb_orphan_partial(struct sk_buff *skb);
> void sock_rfree(struct sk_buff *skb);
> +void sock_efree(struct sk_buff *skb);
> void sock_edemux(struct sk_buff *skb);
>
> int sock_setsockopt(struct socket *sock, int level, int op,
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 697e696..a936a40 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -3511,6 +3511,27 @@ struct sk_buff *sock_dequeue_err_skb(struct sock *sk)
> }
> EXPORT_SYMBOL(sock_dequeue_err_skb);
>
> +struct sk_buff *skb_clone_sk(struct sk_buff *skb)
> +{
> + struct sock *sk = skb->sk;
> + struct sk_buff *clone;
> +
> + if (!sk || !atomic_inc_not_zero(&sk->sk_refcnt))
> + return NULL;
> +
> + clone = skb_clone(skb, GFP_ATOMIC);
> + if (!clone) {
> + sock_put(sk);
> + return NULL;
> + }
> +
> + clone->sk = sk;
> + clone->destructor = sock_efree;
> +
> + return clone;
> +}
> +EXPORT_SYMBOL(skb_clone_sk);
> +
> static void __skb_complete_tx_timestamp(struct sk_buff *skb,
> struct sock *sk,
> int tstype)
> @@ -3540,14 +3561,11 @@ void skb_complete_tx_timestamp(struct sk_buff *skb,
> {
> struct sock *sk = skb->sk;
>
> - skb->sk = NULL;
> + /* take a reference to prevent skb_orphan() from freeing the socket */
> + sock_hold(sk);
>
> - if (hwtstamps) {
> - *skb_hwtstamps(skb) = *hwtstamps;
> - __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND);
> - } else {
> - kfree_skb(skb);
> - }
> + *skb_hwtstamps(skb) = *hwtstamps;
> + __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND);
>
> sock_put(sk);
> }
> diff --git a/net/core/sock.c b/net/core/sock.c
> index f1a638e..d04005c 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -1637,6 +1637,12 @@ void sock_rfree(struct sk_buff *skb)
> }
> EXPORT_SYMBOL(sock_rfree);
>
> +void sock_efree(struct sk_buff *skb)
> +{
> + sock_put(skb->sk);
> +}
> +EXPORT_SYMBOL(sock_efree);
> +
> void sock_edemux(struct sk_buff *skb)
> {
> struct sock *sk = skb->sk;
> diff --git a/net/core/timestamping.c b/net/core/timestamping.c
> index f48a59f..43d3dd6 100644
> --- a/net/core/timestamping.c
> +++ b/net/core/timestamping.c
> @@ -36,10 +36,9 @@ void skb_clone_tx_timestamp(struct sk_buff *skb)
> {
> struct phy_device *phydev;
> struct sk_buff *clone;
> - struct sock *sk = skb->sk;
> unsigned int type;
>
> - if (!sk)
> + if (!skb->sk)
> return;
>
> type = classify(skb);
> @@ -48,16 +47,9 @@ 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))
> + clone = skb_clone_sk(skb);
> + if (!clone)
> return;
> -
> - clone = skb_clone(skb, GFP_ATOMIC);
> - if (!clone) {
> - sock_put(sk);
> - return;
> - }
> -
> - clone->sk = sk;
> phydev->drv->txtstamp(phydev, clone, type);
> }
> }
>
> --
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