os_mbuf_get_pkthdr

struct os_mbuf *os_mbuf_get_pkthdr(struct os_mbuf_pool *omp, uint8_t pkthdr_len);

Allocates a packet header mbuf from the mbuf pool pointed to by omp. Adds a user header of length pkthdr_len to packet header mbuf.

Arguments

Arguments	Description
om	Pointer to mbuf pool from which to allocate mbuf
pkthdr_len	The user header packet length to allocate for the packet header mbuf

Returned values

Returns a pointer to the allocated mbuf or NULL if there are no mbufs available or the user packet header was too large.

Notes

The packet header mbuf returned will have its data pointer incremented by the sizeof(struct os_mbuf_pkthdr) as well as the amount of user header data (i.e. pkthdr_len). In other words, the data pointer is offset from the start of the mbuf by: sizeof(struct os_mbuf) + sizeof(struct os_mbuf_pkthdr) + pkthdr_len. The om_pkthdr_len element in the allocated mbuf is set to: sizeof(struct os_mbuf_pkthdr) + pkthdr_len.

Example

	struct os_mbuf *om;
    struct my_user_header my_hdr;

    /* Get a packet header mbuf with a user header in it */
    om = os_mbuf_get_pkthdr(&g_mbuf_pool, sizeof(struct my_user_header));
    if (om) {
        /* Packet header mbuf was allocated */
    }