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authorMagnus Karlsson <magnus.karlsson@intel.com>2021-12-14 11:26:07 +0100
committerDaniel Borkmann <daniel@iogearbox.net>2021-12-14 15:20:54 +0100
commitbd0687c18e635b63233dc87f38058cd728802ab4 (patch)
tree02b057f615267d043102711e3a31ea9e998ef3f1 /net/xdp
parent0be2516f865f5a876837184a8385163ff64a5889 (diff)
downloadlinux-bd0687c18e635b63233dc87f38058cd728802ab4.tar.bz2
xsk: Do not sleep in poll() when need_wakeup set
Do not sleep in poll() when the need_wakeup flag is set. When this flag is set, the application needs to explicitly wake up the driver with a syscall (poll, recvmsg, sendmsg, etc.) to guarantee that Rx and/or Tx processing will be processed promptly. But the current code in poll(), sleeps first then wakes up the driver. This means that no driver processing will occur (baring any interrupts) until the timeout has expired. Fix this by checking the need_wakeup flag first and if set, wake the driver and return to the application. Only if need_wakeup is not set should the process sleep if there is a timeout set in the poll() call. Fixes: 77cd0d7b3f25 ("xsk: add support for need_wakeup flag in AF_XDP rings") Reported-by: Keith Wiles <keith.wiles@intel.com> Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com> Link: https://lore.kernel.org/bpf/20211214102607.7677-1-magnus.karlsson@gmail.com
Diffstat (limited to 'net/xdp')
-rw-r--r--net/xdp/xsk.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index f16074eb53c7..7a466ea962c5 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -677,8 +677,6 @@ static __poll_t xsk_poll(struct file *file, struct socket *sock,
struct xdp_sock *xs = xdp_sk(sk);
struct xsk_buff_pool *pool;
- sock_poll_wait(file, sock, wait);
-
if (unlikely(!xsk_is_bound(xs)))
return mask;
@@ -690,6 +688,8 @@ static __poll_t xsk_poll(struct file *file, struct socket *sock,
else
/* Poll needs to drive Tx also in copy mode */
__xsk_sendmsg(sk);
+ } else {
+ sock_poll_wait(file, sock, wait);
}
if (xs->rx && !xskq_prod_is_empty(xs->rx))