Function rss_soft_m2cpuid_v4

freebsd/netinet/in_rss.c:376–399

* Similar to rss_m2cpuid, but designed to be used by the IP NETISR * on incoming frames. * * If an existing RSS hash exists and it matches what the configured * hashing is, then use it. * * If there's an existing RSS hash but the desired hash is different, * or if there's no useful RSS hash, then calculate it via * the software path. * * XXX TODO: definitely want statistics here! */

 * XXX TODO: definitely want statistics here!
 */
struct mbuf *
rss_soft_m2cpuid_v4(struct mbuf *m, uintptr_t source, u_int *cpuid)
{
	uint32_t hash_val, hash_type;
	int ret;

	M_ASSERTPKTHDR(m);

	ret = rss_mbuf_software_hash_v4(m, RSS_HASH_PKT_INGRESS,
	    &hash_val, &hash_type);
	if (ret > 0) {
		/* mbuf has a valid hash already; don't need to modify it */
		*cpuid = rss_hash2cpuid(m->m_pkthdr.flowid, M_HASHTYPE_GET(m));
	} else if (ret == 0) {
		/* hash was done; update */
		m->m_pkthdr.flowid = hash_val;
		M_HASHTYPE_SET(m, hash_type);
		*cpuid = rss_hash2cpuid(m->m_pkthdr.flowid, M_HASHTYPE_GET(m));
	} else { /* ret < 0 */
		/* no hash was done */
		*cpuid = NETISR_CPUID_NONE;
	}
	return (m);
}