On Thu, Nov 18, 2021 at 11:58:24PM +0100, [email protected] wrote: > From: Martin Wilck <[email protected]> > > send_packet() may busy-loop. By polling for POLLOUT, we can > avoid that, even if it's very unlikely in practice. >
The last time I reviewed this, I mentioned that when we fall through from CLT_WORK to CLT_SEND, the client hasn't checked for a POLLOUT revent, so it's possible to block here. I'm not sure that we care. If not Reviewed-by: Benjamin Marzinski <[email protected]> > Signed-off-by: Martin Wilck <[email protected]> > --- > multipathd/uxlsnr.c | 35 ++++++++++++++++++++++++++--------- > 1 file changed, 26 insertions(+), 9 deletions(-) > > diff --git a/multipathd/uxlsnr.c b/multipathd/uxlsnr.c > index 45fe7b5..6213454 100644 > --- a/multipathd/uxlsnr.c > +++ b/multipathd/uxlsnr.c > @@ -447,7 +447,6 @@ static int client_state_machine(struct client *c, struct > vectors *vecs, > short revents) > { > ssize_t n; > - const char *buf; > > condlog(4, "%s: cli[%d] poll=%x state=%d cmd=\"%s\" repl \"%s\"", > __func__, > c->fd, revents, c->state, c->cmd, get_strbuf_str(&c->reply)); > @@ -544,16 +543,31 @@ static int client_state_machine(struct client *c, > struct vectors *vecs, > if (get_strbuf_len(&c->reply) == 0) > default_reply(c, c->error); > > - buf = get_strbuf_str(&c->reply); > + if (c->cmd_len == 0) { > + size_t len = get_strbuf_len(&c->reply) + 1; > > - if (send_packet(c->fd, buf) != 0) > - dead_client(c); > - else > - condlog(4, "cli[%d]: Reply [%zu bytes]", c->fd, > - get_strbuf_len(&c->reply) + 1); > - reset_strbuf(&c->reply); > + if (send(c->fd, &len, sizeof(len), MSG_NOSIGNAL) > + != sizeof(len)) > + c->error = -ECONNRESET; > + c->cmd_len = len; > + return STM_BREAK; > + } > > - set_client_state(c, CLT_RECV); > + if (c->len < c->cmd_len) { > + const char *buf = get_strbuf_str(&c->reply); > + > + n = send(c->fd, buf + c->len, c->cmd_len, MSG_NOSIGNAL); > + if (n == -1) { > + if (!(errno == EAGAIN || errno == EINTR)) > + c->error = -ECONNRESET; > + } else > + c->len += n; > + } > + > + if (c->len >= c->cmd_len) { > + condlog(4, "cli[%d]: Reply [%zu bytes]", c->fd, > c->cmd_len); > + set_client_state(c, CLT_RECV); > + } > return STM_BREAK; > > default: > @@ -686,6 +700,9 @@ void *uxsock_listen(long ux_sock, void *trigger_data) > case CLT_RECV: > polls[i].events = POLLIN; > break; > + case CLT_SEND: > + polls[i].events = POLLOUT; > + break; > default: > /* don't poll for this client */ > continue; > -- > 2.33.1 -- dm-devel mailing list [email protected] https://listman.redhat.com/mailman/listinfo/dm-devel
