1 files changed, 75 insertions, 56 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 06bedeb0d49e..c5cd016f5120 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -34,11 +34,82 @@
 #include <linux/netdev_features.h>
 #include <net/flow_keys.h>
+/* A. Checksumming of received packets by device.
+ *
+ * CHECKSUM_NONE:
+ *
+ *   Device failed to checksum this packet e.g. due to lack of capabilities.
+ *   The packet contains full (though not verified) checksum in packet but
+ *   not in skb->csum. Thus, skb->csum is undefined in this case.
+ *
+ * CHECKSUM_UNNECESSARY:
+ *
+ *   The hardware you're dealing with doesn't calculate the full checksum
+ *   (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
+ *   for specific protocols e.g. TCP/UDP/SCTP, then, for such packets it will
+ *   set CHECKSUM_UNNECESSARY if their checksums are okay. skb->csum is still
+ *   undefined in this case though. It is a bad option, but, unfortunately,
+ *   nowadays most vendors do this. Apparently with the secret goal to sell
+ *   you new devices, when you will add new protocol to your host, f.e. IPv6 8)
+ *
+ * CHECKSUM_COMPLETE:
+ *
+ *   This is the most generic way. The device supplied checksum of the _whole_
+ *   packet as seen by netif_rx() and fills out in skb->csum. Meaning, the
+ *   hardware doesn't need to parse L3/L4 headers to implement this.
+ *
+ *   Note: Even if device supports only some protocols, but is able to produce
+ *   skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
+ *
+ * CHECKSUM_PARTIAL:
+ *
+ *   This is identical to the case for output below. This may occur on a packet
+ *   received directly from another Linux OS, e.g., a virtualized Linux kernel
+ *   on the same host. The packet can be treated in the same way as
+ *   CHECKSUM_UNNECESSARY, except that on output (i.e., forwarding) the
+ *   checksum must be filled in by the OS or the hardware.
+ *
+ * B. Checksumming on output.
+ *
+ * CHECKSUM_NONE:
+ *
+ *   The skb was already checksummed by the protocol, or a checksum is not
+ *   required.
+ *
+ * CHECKSUM_PARTIAL:
+ *
+ *   The device is required to checksum the packet as seen by hard_start_xmit()
+ *   from skb->csum_start up to the end, and to record/write the checksum at
+ *   offset skb->csum_start + skb->csum_offset.
+ *
+ *   The device must show its capabilities in dev->features, set up at device
+ *   setup time, e.g. netdev_features.h:
+ *
+ *      NETIF_F_HW_CSUM - It's a clever device, it's able to checksum everything.
+ *      NETIF_F_IP_CSUM - Device is dumb, it's able to checksum only TCP/UDP over
+ *                        IPv4. Sigh. Vendors like this way for an unknown reason.
+ *                        Though, see comment above about CHECKSUM_UNNECESSARY. 8)
+ *      NETIF_F_IPV6_CSUM - About as dumb as the last one but does IPv6 instead.
+ *      NETIF_F_...     - Well, you get the picture.
+ *
+ * CHECKSUM_UNNECESSARY:
+ *
+ *   Normally, the device will do per protocol specific checksumming. Protocol
+ *   implementations that do not want the NIC to perform the checksum
+ *   calculation should use this flag in their outgoing skbs.
+ *
+ *      NETIF_F_FCOE_CRC - This indicates that the device can do FCoE FC CRC
+ *                         offload. Correspondingly, the FCoE protocol driver
+ *                         stack should use CHECKSUM_UNNECESSARY.
+ *
+ * Any questions? No questions, good.           --ANK
+ */
 /* Don't change this without changing skb_csum_unnecessary! */
-#define CHECKSUM_NONE 0
+#define CHECKSUM_NONE           0
-#define CHECKSUM_UNNECESSARY 1
+#define CHECKSUM_UNNECESSARY    1
-#define CHECKSUM_COMPLETE 2
+#define CHECKSUM_COMPLETE       2
-#define CHECKSUM_PARTIAL 3
+#define CHECKSUM_PARTIAL        3
 #define SKB_DATA_ALIGN(X)       (((X) + (SMP_CACHE_BYTES - 1)) & \
                                 ~(SMP_CACHE_BYTES - 1))
@@ -54,58 +125,6 @@
                         SKB_DATA_ALIGN(sizeof(struct sk_buff)) +       \
                         SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
-/* A. Checksumming of received packets by device.
- *
- *      NONE: device failed to checksum this packet.
- *              skb->csum is undefined.
- *
- *      UNNECESSARY: device parsed packet and wouldbe verified checksum.
- *              skb->csum is undefined.
- *            It is bad option, but, unfortunately, many of vendors do this.
- *            Apparently with secret goal to sell you new device, when you
- *            will add new protocol to your host. F.e. IPv6. 8)
- *
- *      COMPLETE: the most generic way. Device supplied checksum of _all_
- *          the packet as seen by netif_rx in skb->csum.
- *          NOTE: Even if device supports only some protocols, but
- *          is able to produce some skb->csum, it MUST use COMPLETE,
- *          not UNNECESSARY.
- *
- *      PARTIAL: identical to the case for output below.  This may occur
- *          on a packet received directly from another Linux OS, e.g.,
- *          a virtualised Linux kernel on the same host.  The packet can
- *          be treated in the same way as UNNECESSARY except that on
- *          output (i.e., forwarding) the checksum must be filled in
- *          by the OS or the hardware.
- *
- * B. Checksumming on output.
- *
- *      NONE: skb is checksummed by protocol or csum is not required.
- *
- *      PARTIAL: device is required to csum packet as seen by hard_start_xmit
- *      from skb->csum_start to the end and to record the checksum
- *      at skb->csum_start + skb->csum_offset.
- *
- *      Device must show its capabilities in dev->features, set
- *      at device setup time.
- *      NETIF_F_HW_CSUM - it is clever device, it is able to checksum
- *                        everything.
- *      NETIF_F_IP_CSUM - device is dumb. It is able to csum only
- *                        TCP/UDP over IPv4. Sigh. Vendors like this
- *                        way by an unknown reason. Though, see comment above
- *                        about CHECKSUM_UNNECESSARY. 8)
- *      NETIF_F_IPV6_CSUM about as dumb as the last one but does IPv6 instead.
- *
- *      UNNECESSARY: device will do per protocol specific csum. Protocol drivers
- *      that do not want net to perform the checksum calculation should use
- *      this flag in their outgoing skbs.
- *      NETIF_F_FCOE_CRC  this indicates the device can do FCoE FC CRC
- *                        offload. Correspondingly, the FCoE protocol driver
- *                        stack should use CHECKSUM_UNNECESSARY.
- *
- *      Any questions? No questions, good.              --ANK
- */
 struct net_device;
 struct scatterlist;
 struct pipe_inode_info;

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 06bedeb0d49e..c5cd016f5120 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h
@@ -34,11 +34,82 @@
34	#include <linux/netdev_features.h>	34	#include <linux/netdev_features.h>
35	#include <net/flow_keys.h>	35	#include <net/flow_keys.h>
36		36
		37	/* A. Checksumming of received packets by device.
		38	*
		39	* CHECKSUM_NONE:
		40	*
		41	* Device failed to checksum this packet e.g. due to lack of capabilities.
		42	* The packet contains full (though not verified) checksum in packet but
		43	* not in skb->csum. Thus, skb->csum is undefined in this case.
		44	*
		45	* CHECKSUM_UNNECESSARY:
		46	*
		47	* The hardware you're dealing with doesn't calculate the full checksum
		48	* (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
		49	* for specific protocols e.g. TCP/UDP/SCTP, then, for such packets it will
		50	* set CHECKSUM_UNNECESSARY if their checksums are okay. skb->csum is still
		51	* undefined in this case though. It is a bad option, but, unfortunately,
		52	* nowadays most vendors do this. Apparently with the secret goal to sell
		53	* you new devices, when you will add new protocol to your host, f.e. IPv6 8)
		54	*
		55	* CHECKSUM_COMPLETE:
		56	*
		57	* This is the most generic way. The device supplied checksum of the _whole_
		58	* packet as seen by netif_rx() and fills out in skb->csum. Meaning, the
		59	* hardware doesn't need to parse L3/L4 headers to implement this.
		60	*
		61	* Note: Even if device supports only some protocols, but is able to produce
		62	* skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
		63	*
		64	* CHECKSUM_PARTIAL:
		65	*
		66	* This is identical to the case for output below. This may occur on a packet
		67	* received directly from another Linux OS, e.g., a virtualized Linux kernel
		68	* on the same host. The packet can be treated in the same way as
		69	* CHECKSUM_UNNECESSARY, except that on output (i.e., forwarding) the
		70	* checksum must be filled in by the OS or the hardware.
		71	*
		72	* B. Checksumming on output.
		73	*
		74	* CHECKSUM_NONE:
		75	*
		76	* The skb was already checksummed by the protocol, or a checksum is not
		77	* required.
		78	*
		79	* CHECKSUM_PARTIAL:
		80	*
		81	* The device is required to checksum the packet as seen by hard_start_xmit()
		82	* from skb->csum_start up to the end, and to record/write the checksum at
		83	* offset skb->csum_start + skb->csum_offset.
		84	*
		85	* The device must show its capabilities in dev->features, set up at device
		86	* setup time, e.g. netdev_features.h:
		87	*
		88	* NETIF_F_HW_CSUM - It's a clever device, it's able to checksum everything.
		89	* NETIF_F_IP_CSUM - Device is dumb, it's able to checksum only TCP/UDP over
		90	* IPv4. Sigh. Vendors like this way for an unknown reason.
		91	* Though, see comment above about CHECKSUM_UNNECESSARY. 8)
		92	* NETIF_F_IPV6_CSUM - About as dumb as the last one but does IPv6 instead.
		93	* NETIF_F_... - Well, you get the picture.
		94	*
		95	* CHECKSUM_UNNECESSARY:
		96	*
		97	* Normally, the device will do per protocol specific checksumming. Protocol
		98	* implementations that do not want the NIC to perform the checksum
		99	* calculation should use this flag in their outgoing skbs.
		100	*
		101	* NETIF_F_FCOE_CRC - This indicates that the device can do FCoE FC CRC
		102	* offload. Correspondingly, the FCoE protocol driver
		103	* stack should use CHECKSUM_UNNECESSARY.
		104	*
		105	* Any questions? No questions, good. --ANK
		106	*/
		107
37	/* Don't change this without changing skb_csum_unnecessary! */	108	/* Don't change this without changing skb_csum_unnecessary! */
38	#define CHECKSUM_NONE 0	109	#define CHECKSUM_NONE 0
39	#define CHECKSUM_UNNECESSARY 1	110	#define CHECKSUM_UNNECESSARY 1
40	#define CHECKSUM_COMPLETE 2	111	#define CHECKSUM_COMPLETE 2
41	#define CHECKSUM_PARTIAL 3	112	#define CHECKSUM_PARTIAL 3
42		113
43	#define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \	114	#define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \
44	~(SMP_CACHE_BYTES - 1))	115	~(SMP_CACHE_BYTES - 1))
@@ -54,58 +125,6 @@
54	SKB_DATA_ALIGN(sizeof(struct sk_buff)) + \	125	SKB_DATA_ALIGN(sizeof(struct sk_buff)) + \
55	SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))	126	SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
56		127
57	/* A. Checksumming of received packets by device.
58	*
59	* NONE: device failed to checksum this packet.
60	* skb->csum is undefined.
61	*
62	* UNNECESSARY: device parsed packet and wouldbe verified checksum.
63	* skb->csum is undefined.
64	* It is bad option, but, unfortunately, many of vendors do this.
65	* Apparently with secret goal to sell you new device, when you
66	* will add new protocol to your host. F.e. IPv6. 8)
67	*
68	* COMPLETE: the most generic way. Device supplied checksum of _all_
69	* the packet as seen by netif_rx in skb->csum.
70	* NOTE: Even if device supports only some protocols, but
71	* is able to produce some skb->csum, it MUST use COMPLETE,
72	* not UNNECESSARY.
73	*
74	* PARTIAL: identical to the case for output below. This may occur
75	* on a packet received directly from another Linux OS, e.g.,
76	* a virtualised Linux kernel on the same host. The packet can
77	* be treated in the same way as UNNECESSARY except that on
78	* output (i.e., forwarding) the checksum must be filled in
79	* by the OS or the hardware.
80	*
81	* B. Checksumming on output.
82	*
83	* NONE: skb is checksummed by protocol or csum is not required.
84	*
85	* PARTIAL: device is required to csum packet as seen by hard_start_xmit
86	* from skb->csum_start to the end and to record the checksum
87	* at skb->csum_start + skb->csum_offset.
88	*
89	* Device must show its capabilities in dev->features, set
90	* at device setup time.
91	* NETIF_F_HW_CSUM - it is clever device, it is able to checksum
92	* everything.
93	* NETIF_F_IP_CSUM - device is dumb. It is able to csum only
94	* TCP/UDP over IPv4. Sigh. Vendors like this
95	* way by an unknown reason. Though, see comment above
96	* about CHECKSUM_UNNECESSARY. 8)
97	* NETIF_F_IPV6_CSUM about as dumb as the last one but does IPv6 instead.
98	*
99	* UNNECESSARY: device will do per protocol specific csum. Protocol drivers
100	* that do not want net to perform the checksum calculation should use
101	* this flag in their outgoing skbs.
102	* NETIF_F_FCOE_CRC this indicates the device can do FCoE FC CRC
103	* offload. Correspondingly, the FCoE protocol driver
104	* stack should use CHECKSUM_UNNECESSARY.
105	*
106	* Any questions? No questions, good. --ANK
107	*/
108
109	struct net_device;	128	struct net_device;
110	struct scatterlist;	129	struct scatterlist;
111	struct pipe_inode_info;	130	struct pipe_inode_info;