Commit b68b0dd0 authored May 05, 2019 by Vladimir Oltean Committed by David S. Miller May 05, 2019

net: dsa: Keep private info in the skb->cb



Map a DSA structure over the 48-byte control block that will hold
skb info on transmit and receive. This is only for use within the DSA
processing layer (e.g. communicating between DSA core and tagger) and
not for passing info around with other layers such as the master net
device.

Also add a DSA_SKB_CB_PRIV() macro which retrieves a pointer to the
space up to 48 bytes that the DSA structure does not use. This space can
be used for drivers to add their own private info.

One use is for the PTP timestamping code path. When cloning a skb,
annotate the original with a pointer to the clone, which the driver can
then find easily and place the timestamp to. This avoids the need of a
separate queue to hold clones and a way to match an original to a cloned
skb.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent cc1939e4

include/net/dsa.h

+31 −0

Original line number	Diff line number	Diff line
		@@ -83,6 +83,37 @@ struct dsa_device_ops {
		#define MODULE_ALIAS_DSA_TAG_DRIVER(__proto) \
		MODULE_ALIAS(DSA_TAG_DRIVER_ALIAS __stringify(__proto##_VALUE))

		struct dsa_skb_cb {
		struct sk_buff *clone;
		};

		struct __dsa_skb_cb {
		struct dsa_skb_cb cb;
		u8 priv[48 - sizeof(struct dsa_skb_cb)];
		};

		#define __DSA_SKB_CB(skb) ((struct __dsa_skb_cb *)((skb)->cb))

		#define DSA_SKB_CB(skb) ((struct dsa_skb_cb *)((skb)->cb))

		#define DSA_SKB_CB_COPY(nskb, skb) \
		{ __DSA_SKB_CB(nskb) = __DSA_SKB_CB(skb); }

		#define DSA_SKB_CB_ZERO(skb) \
		{ *__DSA_SKB_CB(skb) = (struct __dsa_skb_cb) {0}; }

		#define DSA_SKB_CB_PRIV(skb) \
		((void *)(skb)->cb + offsetof(struct __dsa_skb_cb, priv))

		#define DSA_SKB_CB_CLONE(_clone, _skb) \
		{ \
		struct sk_buff *clone = _clone; \
		struct sk_buff *skb = _skb; \
		\
		DSA_SKB_CB_COPY(clone, skb); \
		DSA_SKB_CB(skb)->clone = clone; \
		}

		struct dsa_switch_tree {
		struct list_head list;

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