diff options
Diffstat (limited to 'include/linux/skbuff.h')
| -rw-r--r-- | include/linux/skbuff.h | 195 |
1 files changed, 162 insertions, 33 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 75f136a22..d3fcd4591 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -39,11 +39,55 @@ #include <linux/in6.h> #include <net/flow.h> -/* A. Checksumming of received packets by device. +/* The interface for checksum offload between the stack and networking drivers + * is as follows... + * + * A. IP checksum related features + * + * Drivers advertise checksum offload capabilities in the features of a device. + * From the stack's point of view these are capabilities offered by the driver, + * a driver typically only advertises features that it is capable of offloading + * to its device. + * + * The checksum related features are: + * + * NETIF_F_HW_CSUM - The driver (or its device) is able to compute one + * IP (one's complement) checksum for any combination + * of protocols or protocol layering. The checksum is + * computed and set in a packet per the CHECKSUM_PARTIAL + * interface (see below). + * + * NETIF_F_IP_CSUM - Driver (device) is only able to checksum plain + * TCP or UDP packets over IPv4. These are specifically + * unencapsulated packets of the form IPv4|TCP or + * IPv4|UDP where the Protocol field in the IPv4 header + * is TCP or UDP. The IPv4 header may contain IP options + * This feature cannot be set in features for a device + * with NETIF_F_HW_CSUM also set. This feature is being + * DEPRECATED (see below). + * + * NETIF_F_IPV6_CSUM - Driver (device) is only able to checksum plain + * TCP or UDP packets over IPv6. These are specifically + * unencapsulated packets of the form IPv6|TCP or + * IPv4|UDP where the Next Header field in the IPv6 + * header is either TCP or UDP. IPv6 extension headers + * are not supported with this feature. This feature + * cannot be set in features for a device with + * NETIF_F_HW_CSUM also set. This feature is being + * DEPRECATED (see below). + * + * NETIF_F_RXCSUM - Driver (device) performs receive checksum offload. + * This flag is used only used to disable the RX checksum + * feature for a device. The stack will accept receive + * checksum indication in packets received on a device + * regardless of whether NETIF_F_RXCSUM is set. + * + * B. Checksumming of received packets by device. Indication of checksum + * verification is in set skb->ip_summed. Possible values are: * * CHECKSUM_NONE: * - * Device failed to checksum this packet e.g. due to lack of capabilities. + * Device did not 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. * @@ -53,9 +97,8 @@ * (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums * for specific protocols. 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) + * though. A driver or device must never modify the checksum field in the + * packet even if checksum is verified. * * CHECKSUM_UNNECESSARY is applicable to following protocols: * TCP: IPv6 and IPv4. @@ -96,40 +139,77 @@ * packet that are after the checksum being offloaded are not considered to * be verified. * - * B. Checksumming on output. - * - * CHECKSUM_NONE: - * - * The skb was already checksummed by the protocol, or a checksum is not - * required. + * C. Checksumming on transmit for non-GSO. The stack requests checksum offload + * in the skb->ip_summed for a packet. Values are: * * CHECKSUM_PARTIAL: * - * The device is required to checksum the packet as seen by hard_start_xmit() + * The driver 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. + * offset skb->csum_start + skb->csum_offset. A driver may verify that the + * csum_start and csum_offset values are valid values given the length and + * offset of the packet, however they should not attempt to validate that the + * checksum refers to a legitimate transport layer checksum-- it is the + * purview of the stack to validate that csum_start and csum_offset are set + * correctly. + * + * When the stack requests checksum offload for a packet, the driver MUST + * ensure that the checksum is set correctly. A driver can either offload the + * checksum calculation to the device, or call skb_checksum_help (in the case + * that the device does not support offload for a particular checksum). + * + * NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM are being deprecated in favor of + * NETIF_F_HW_CSUM. New devices should use NETIF_F_HW_CSUM to indicate + * checksum offload capability. If a device has limited checksum capabilities + * (for instance can only perform NETIF_F_IP_CSUM or NETIF_F_IPV6_CSUM as + * described above) a helper function can be called to resolve + * CHECKSUM_PARTIAL. The helper functions are skb_csum_off_chk*. The helper + * function takes a spec argument that describes the protocol layer that is + * supported for checksum offload and can be called for each packet. If a + * packet does not match the specification for offload, skb_checksum_help + * is called to resolve the checksum. * - * The device must show its capabilities in dev->features, set up at device - * setup time, e.g. netdev_features.h: + * CHECKSUM_NONE: * - * 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. + * The skb was already checksummed by the protocol, or a checksum is not + * required. * * 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. + * This has the same meaning on as CHECKSUM_NONE for checksum offload on + * output. * - * 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 + * CHECKSUM_COMPLETE: + * Not used in checksum output. If a driver observes a packet with this value + * set in skbuff, if should treat as CHECKSUM_NONE being set. + * + * D. Non-IP checksum (CRC) offloads + * + * NETIF_F_SCTP_CRC - This feature indicates that a device is capable of + * offloading the SCTP CRC in a packet. To perform this offload the stack + * will set ip_summed to CHECKSUM_PARTIAL and set csum_start and csum_offset + * accordingly. Note the there is no indication in the skbuff that the + * CHECKSUM_PARTIAL refers to an SCTP checksum, a driver that supports + * both IP checksum offload and SCTP CRC offload must verify which offload + * is configured for a packet presumably by inspecting packet headers. + * + * NETIF_F_FCOE_CRC - This feature indicates that a device is capable of + * offloading the FCOE CRC in a packet. To perform this offload the stack + * will set ip_summed to CHECKSUM_PARTIAL and set csum_start and csum_offset + * accordingly. Note the there is no indication in the skbuff that the + * CHECKSUM_PARTIAL refers to an FCOE checksum, a driver that supports + * both IP checksum offload and FCOE CRC offload must verify which offload + * is configured for a packet presumably by inspecting packet headers. + * + * E. Checksumming on output with GSO. + * + * In the case of a GSO packet (skb_is_gso(skb) is true), checksum offload + * is implied by the SKB_GSO_* flags in gso_type. Most obviously, if the + * gso_type is SKB_GSO_TCPV4 or SKB_GSO_TCPV6, TCP checksum offload as + * part of the GSO operation is implied. If a checksum is being offloaded + * with GSO then ip_summed is CHECKSUM_PARTIAL, csum_start and csum_offset + * are set to refer to the outermost checksum being offload (two offloaded + * checksums are possible with UDP encapsulation). */ /* Don't change this without changing skb_csum_unnecessary! */ @@ -834,7 +914,7 @@ struct sk_buff_fclones { * skb_fclone_busy - check if fclone is busy * @skb: buffer * - * Returns true is skb is a fast clone, and its clone is not freed. + * Returns true if skb is a fast clone, and its clone is not freed. * Some drivers call skb_orphan() in their ndo_start_xmit(), * so we also check that this didnt happen. */ @@ -1083,9 +1163,6 @@ static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from) static inline void skb_sender_cpu_clear(struct sk_buff *skb) { -#ifdef CONFIG_XPS - skb->sender_cpu = 0; -#endif } #ifdef NET_SKBUFF_DATA_USES_OFFSET @@ -1908,6 +1985,30 @@ static inline void skb_reserve(struct sk_buff *skb, int len) skb->tail += len; } +/** + * skb_tailroom_reserve - adjust reserved_tailroom + * @skb: buffer to alter + * @mtu: maximum amount of headlen permitted + * @needed_tailroom: minimum amount of reserved_tailroom + * + * Set reserved_tailroom so that headlen can be as large as possible but + * not larger than mtu and tailroom cannot be smaller than + * needed_tailroom. + * The required headroom should already have been reserved before using + * this function. + */ +static inline void skb_tailroom_reserve(struct sk_buff *skb, unsigned int mtu, + unsigned int needed_tailroom) +{ + SKB_LINEAR_ASSERT(skb); + if (mtu < skb_tailroom(skb) - needed_tailroom) + /* use at most mtu */ + skb->reserved_tailroom = skb_tailroom(skb) - mtu; + else + /* use up to all available space */ + skb->reserved_tailroom = needed_tailroom; +} + #define ENCAP_TYPE_ETHER 0 #define ENCAP_TYPE_IPPROTO 1 @@ -1943,6 +2044,11 @@ static inline unsigned char *skb_inner_transport_header(const struct sk_buff return skb->head + skb->inner_transport_header; } +static inline int skb_inner_transport_offset(const struct sk_buff *skb) +{ + return skb_inner_transport_header(skb) - skb->data; +} + static inline void skb_reset_inner_transport_header(struct sk_buff *skb) { skb->inner_transport_header = skb->data - skb->head; @@ -2724,6 +2830,23 @@ static inline void skb_postpull_rcsum(struct sk_buff *skb, unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len); +static inline void skb_postpush_rcsum(struct sk_buff *skb, + const void *start, unsigned int len) +{ + /* For performing the reverse operation to skb_postpull_rcsum(), + * we can instead of ... + * + * skb->csum = csum_add(skb->csum, csum_partial(start, len, 0)); + * + * ... just use this equivalent version here to save a few + * instructions. Feeding csum of 0 in csum_partial() and later + * on adding skb->csum is equivalent to feed skb->csum in the + * first place. + */ + if (skb->ip_summed == CHECKSUM_COMPLETE) + skb->csum = csum_partial(start, len, skb->csum); +} + /** * pskb_trim_rcsum - trim received skb and update checksum * @skb: buffer to trim @@ -2789,6 +2912,12 @@ static inline void skb_frag_list_init(struct sk_buff *skb) #define skb_walk_frags(skb, iter) \ for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next) + +int __skb_wait_for_more_packets(struct sock *sk, int *err, long *timeo_p, + const struct sk_buff *skb); +struct sk_buff *__skb_try_recv_datagram(struct sock *sk, unsigned flags, + int *peeked, int *off, int *err, + struct sk_buff **last); struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags, int *peeked, int *off, int *err); struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock, |