On Tue, Feb 08, 2022 at 09:12:11AM +0000, Visa Hankala wrote:
> Now that poll(2) is based on kqueue, the old, non-MP-safe poll backend
> is not used any longer. Event sources can call KNOTE() directly instead
> of selwakeup().
>
> This diff does the KNOTE() conversion for pipes and sockets, removing
> a kernel-locked section from a frequently used code path. The related
> event filters do not use the hint value, hence passing 0 rather than
> NOTE_SUBMIT.
This patch is still valid. It also paves the way for the removal
of fo_poll member from struct file.
Testers are welcome.
> Index: kern/sys_pipe.c
> ===================================================================
> RCS file: src/sys/kern/sys_pipe.c,v
> retrieving revision 1.133
> diff -u -p -r1.133 sys_pipe.c
> --- kern/sys_pipe.c 13 Dec 2021 14:56:55 -0000 1.133
> +++ kern/sys_pipe.c 8 Feb 2022 08:59:05 -0000
> @@ -381,12 +381,7 @@ pipeselwakeup(struct pipe *cpipe)
> {
> rw_assert_wrlock(cpipe->pipe_lock);
>
> - if (cpipe->pipe_state & PIPE_SEL) {
> - cpipe->pipe_state &= ~PIPE_SEL;
> - selwakeup(&cpipe->pipe_sel);
> - } else {
> - KNOTE(&cpipe->pipe_sel.si_note, 0);
> - }
> + KNOTE(&cpipe->pipe_sel.si_note, 0);
>
> if (cpipe->pipe_state & PIPE_ASYNC)
> pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
> Index: kern/uipc_socket.c
> ===================================================================
> RCS file: src/sys/kern/uipc_socket.c,v
> retrieving revision 1.271
> diff -u -p -r1.271 uipc_socket.c
> --- kern/uipc_socket.c 24 Dec 2021 06:50:16 -0000 1.271
> +++ kern/uipc_socket.c 8 Feb 2022 08:59:05 -0000
> @@ -2049,7 +2049,7 @@ void
> sohasoutofband(struct socket *so)
> {
> pgsigio(&so->so_sigio, SIGURG, 0);
> - selwakeup(&so->so_rcv.sb_sel);
> + KNOTE(&so->so_rcv.sb_sel.si_note, 0);
> }
>
> int
> Index: kern/uipc_socket2.c
> ===================================================================
> RCS file: src/sys/kern/uipc_socket2.c,v
> retrieving revision 1.116
> diff -u -p -r1.116 uipc_socket2.c
> --- kern/uipc_socket2.c 6 Nov 2021 05:26:33 -0000 1.116
> +++ kern/uipc_socket2.c 8 Feb 2022 08:59:06 -0000
> @@ -423,7 +423,7 @@ sowakeup(struct socket *so, struct sockb
> }
> if (sb->sb_flags & SB_ASYNC)
> pgsigio(&so->so_sigio, SIGIO, 0);
> - selwakeup(&sb->sb_sel);
> + KNOTE(&sb->sb_sel.si_note, 0);
> }
>
> /*
>
