From: Martin Wilck <mwilck@xxxxxxxx> 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 <mwilck@xxxxxxxx> --- multipathd/uxlsnr.c | 41 ++++++++++++++++++++++++++++++----------- 1 file changed, 30 insertions(+), 11 deletions(-) diff --git a/multipathd/uxlsnr.c b/multipathd/uxlsnr.c index 1ebcf10..c5da569 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)); @@ -527,7 +526,8 @@ static int client_state_machine(struct client *c, struct vectors *vecs, free_keys(c->cmdvec); c->cmdvec = NULL; set_client_state(c, CLT_SEND); - return STM_CONT; + /* Wait for POLLOUT */ + return STM_BREAK; } else { condlog(4, "%s: cli[%d] waiting for lock", __func__, c->fd); return STM_BREAK; @@ -538,22 +538,38 @@ static int client_state_machine(struct client *c, struct vectors *vecs, free_keys(c->cmdvec); c->cmdvec = NULL; set_client_state(c, CLT_SEND); - return STM_CONT; + /* Wait for POLLOUT */ + return STM_BREAK; case CLT_SEND: 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: @@ -687,6 +703,9 @@ 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 dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel