backports: Add rhashtable_lookup_get_insert_fast()

rhashtable_lookup_get_insert_fast() was added in kernel 4.12 in Linux
upstream commit f9fe1c12d12 ("rhashtable: Add
rhashtable_lookup_get_insert_fast") It is now used by mac80211.

For kernel < 4.9 we already backport the complete rhashtable
implementation, so this is only needed for kernels more recent than 4.9.

This is copied from upstreamn Linux kernel.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
1 file changed