#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_UNNECESSARY 1
-#define CHECKSUM_COMPLETE 2
-#define CHECKSUM_PARTIAL 3
+#define CHECKSUM_NONE 0
+#define CHECKSUM_UNNECESSARY 1
+#define CHECKSUM_COMPLETE 2
+#define CHECKSUM_PARTIAL 3
#define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \
~(SMP_CACHE_BYTES - 1))
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;
projects / ~andy / linux / blobdiff