[PATCH bpf-next v3 04/10] xsk: check need wakeup flag in sendmsg()
From: Björn Töpel <hidden>
Date: 2020-11-19 08:31:37
Also in:
bpf
Subsystem:
networking [general], the rest, xdp sockets (af_xdp) · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Magnus Karlsson, Maciej Fijalkowski
From: Björn Töpel <redacted>
Add a check for need wake up in sendmsg(), so that if a user calls
sendmsg() when no wakeup is needed, do not trigger a wakeup.
To simplify the need wakeup check in the syscall, unconditionally
enable the need wakeup flag for Tx. This has a side-effect for poll();
If poll() is called for a socket without enabled need wakeup, a Tx
wakeup is unconditionally performed.
The wakeup matrix for AF_XDP now looks like:
need wakeup | poll() | sendmsg() | recvmsg()
------------+--------------+-------------+------------
disabled | wake Tx | wake Tx | nop
enabled | check flag; | check flag; | check flag;
| wake Tx/Rx | wake Tx | wake Rx
Signed-off-by: Björn Töpel <redacted>
---
net/xdp/xsk.c | 6 +++++-
net/xdp/xsk_buff_pool.c | 13 ++++++-------
2 files changed, 11 insertions(+), 8 deletions(-)
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 56a52ec75696..bf0f5c34af6c 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c@@ -522,13 +522,17 @@ static int xsk_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len) bool need_wait = !(m->msg_flags & MSG_DONTWAIT); struct sock *sk = sock->sk; struct xdp_sock *xs = xdp_sk(sk); + struct xsk_buff_pool *pool; if (unlikely(!xsk_is_bound(xs))) return -ENXIO; if (unlikely(need_wait)) return -EOPNOTSUPP; - return __xsk_sendmsg(sk); + pool = xs->pool; + if (pool->cached_need_wakeup & XDP_WAKEUP_TX) + return __xsk_sendmsg(sk); + return 0; } static int xsk_recvmsg(struct socket *sock, struct msghdr *m, size_t len, int flags)
diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
index 8a3bf4e1318e..96bb607853ad 100644
--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c@@ -144,14 +144,13 @@ static int __xp_assign_dev(struct xsk_buff_pool *pool, if (err) return err; - if (flags & XDP_USE_NEED_WAKEUP) { + if (flags & XDP_USE_NEED_WAKEUP) pool->uses_need_wakeup = true; - /* Tx needs to be explicitly woken up the first time. - * Also for supporting drivers that do not implement this - * feature. They will always have to call sendto(). - */ - pool->cached_need_wakeup = XDP_WAKEUP_TX; - } + /* Tx needs to be explicitly woken up the first time. Also + * for supporting drivers that do not implement this + * feature. They will always have to call sendto() or poll(). + */ + pool->cached_need_wakeup = XDP_WAKEUP_TX; dev_hold(netdev);
--
2.27.0