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.
Signed-off-by: Martin Wilck <[email protected]> --- multipathd/uxlsnr.c | 39 ++++++++++++++++++++++++++++++++------- 1 file changed, 32 insertions(+), 7 deletions(-) diff --git a/multipathd/uxlsnr.c b/multipathd/uxlsnr.c index 1bf4126..c18b2c4 100644 --- a/multipathd/uxlsnr.c +++ b/multipathd/uxlsnr.c @@ -588,15 +588,37 @@ static void handle_client(struct client *c, struct vectors *vecs, short revents) if (get_strbuf_len(&c->reply) == 0) default_reply(c, c->error); - const char *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; + return; + } + c->cmd_len = len; + return; + } + 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) + return; + else { + c->error = -ECONNRESET; + return; + } + } + c->len += n; + } + if (c->len < c->cmd_len) + /* continue polling */ + return; + + condlog(4, "cli[%d]: Reply [%zu bytes]", c->fd, c->cmd_len); set_client_state(c, CLT_RECV); break; @@ -701,6 +723,9 @@ 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; -- 2.33.0 -- dm-devel mailing list [email protected] https://listman.redhat.com/mailman/listinfo/dm-devel
