Commit 68e5b6aa authored by Magnus Karlsson's avatar Magnus Karlsson Committed by David S. Miller
Browse files

xdp: document xdp_do_flush() before napi_complete_done() 



Document in the XDP_REDIRECT manual section that drivers must call
xdp_do_flush() before napi_complete_done(). The two reasons behind
this can be found following the links below.

Signed-off-by: default avatarMagnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/r/20221220185903.1105011-1-sbohrer@cloudflare.com
Link: https://lore.kernel.org/all/20210624160609.292325-1-toke@redhat.com/


Acked-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bed91ac0

net/core/filter.c

+7 −3
Original line number Diff line number Diff line
@@ -4128,9 +4128,13 @@ static const struct bpf_func_proto bpf_xdp_adjust_meta_proto = { 
 *    bpf_redirect_info to actually enqueue the frame into a map type-specific

 *    bulk queue structure.

 *

 * 3. Before exiting its NAPI poll loop, the driver will call xdp_do_flush(),

 *    which will flush all the different bulk queues, thus completing the

 *    redirect.

 * 3. Before exiting its NAPI poll loop, the driver will call

 *    xdp_do_flush(), which will flush all the different bulk queues,

 *    thus completing the redirect. Note that xdp_do_flush() must be

 *    called before napi_complete_done() in the driver, as the

 *    XDP_REDIRECT logic relies on being inside a single NAPI instance

 *    through to the xdp_do_flush() call for RCU protection of all

 *    in-kernel data structures.

 */

/*

 * Pointers to the map entries will be kept around for this whole sequence of