On Fri, Sep 10, 2021 at 01:41:09PM +0200, mwilck@xxxxxxxx wrote:
> From: Martin Wilck <mwilck@xxxxxxxx>
>
> As a first step towards our state machine, avoid the call to
> read_all() via recv_packet_from_client(). handle_client() is now
> invoked twice for the same connection. The first time it reads
> the command length, and later on it reads the command itself
> piece-wise, as sent by the client. This will be just a single
> read in most cases, but not always.
>
Reviewed-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
> Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
> ---
> multipathd/uxlsnr.c | 90 +++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 75 insertions(+), 15 deletions(-)
>
> diff --git a/multipathd/uxlsnr.c b/multipathd/uxlsnr.c
> index 2fb23c8..eff4f7b 100644
> --- a/multipathd/uxlsnr.c
> +++ b/multipathd/uxlsnr.c
> @@ -292,6 +292,8 @@ static void handle_inotify(int fd, struct watch_descriptors *wds)
> condlog(1, "Multipath configuration updated.\nReload multipathd for changes to take effect");
> }
>
> +static const struct timespec ts_zero = { .tv_sec = 0, };
> +
> static int parse_cmd (char *cmd, char **reply, int *len, void *data,
> int timeout)
> {
> @@ -394,23 +396,78 @@ static int uxsock_trigger(char *str, char **reply, int *len,
> return r;
> }
>
> +static void set_client_state(struct client *c, int state)
> +{
> + switch(state)
> + {
> + case CLT_RECV:
> + reset_strbuf(&c->reply);
> + memset(c->cmd, '\0', sizeof(c->cmd));
> + c->expires = ts_zero;
> + /* fallthrough */
> + case CLT_SEND:
> + /* reuse these fields for next data transfer */
> + c->len = c->cmd_len = 0;
> + break;
> + default:
> + break;
> + }
> + c->state = state;
> +}
> +
> static void handle_client(struct client *c, void *trigger_data)
> {
> int rlen;
> - char *inbuf, *reply;
> + char *reply;
> + ssize_t n;
>
> - if (recv_packet_from_client(c->fd, &inbuf, uxsock_timeout) != 0) {
> - dead_client(c);
> - return;
> + switch (c->state) {
> + case CLT_RECV:
> + if (c->cmd_len == 0) {
> + /*
> + * We got POLLIN; assume that at least the length can
> + * be read immediately.
> + */
> + get_monotonic_time(&c->expires);
> + c->expires.tv_sec += uxsock_timeout / 1000;
> + c->expires.tv_nsec += (uxsock_timeout % 1000) * 1000000;
> + normalize_timespec(&c->expires);
> + n = mpath_recv_reply_len(c->fd, 0);
> + if (n == -1) {
> + condlog(1, "%s: cli[%d]: failed to receive reply len",
> + __func__, c->fd);
> + c->error = -ECONNRESET;
> + } else if (n > _MAX_CMD_LEN) {
> + condlog(1, "%s: cli[%d]: overlong command (%zd bytes)",
> + __func__, c->fd, n);
> + c->error = -ECONNRESET;
> + } else {
> + c->cmd_len = n;
> + condlog(4, "%s: cli[%d]: connected", __func__, c->fd);
> + }
> + /* poll for data */
> + return;
> + } else if (c->len < c->cmd_len) {
> + n = recv(c->fd, c->cmd + c->len, c->cmd_len - c->len, 0);
> + if (n <= 0 && errno != EINTR && errno != EAGAIN) {
> + condlog(1, "%s: cli[%d]: error in recv: %m",
> + __func__, c->fd);
> + c->error = -ECONNRESET;
> + return;
> + }
> + c->len += n;
> + if (c->len < c->cmd_len)
> + /* continue polling */
> + return;
> + set_client_state(c, CLT_PARSE);
> + }
> + break;
> + default:
> + break;
> }
>
> - if (!inbuf) {
> - condlog(4, "recv_packet_from_client get null request");
> - return;
> - }
> -
> - condlog(4, "cli[%d]: Got request [%s]", c->fd, inbuf);
> - uxsock_trigger(inbuf, &reply, &rlen,
> + condlog(4, "cli[%d]: Got request [%s]", c->fd, c->cmd);
> + uxsock_trigger(c->cmd, &reply, &rlen,
> _socket_client_is_root(c->fd),
> trigger_data);
>
> @@ -418,11 +475,12 @@ static void handle_client(struct client *c, void *trigger_data)
> if (send_packet(c->fd, reply) != 0)
> dead_client(c);
> else
> - condlog(4, "cli[%d]: Reply [%d bytes]", c->fd, rlen);
> - FREE(reply);
> - reply = NULL;
> + condlog(4, "cli[%d]: Reply [%zu bytes]", c->fd,
> + get_strbuf_len(&c->reply) + 1);
> + reset_strbuf(&c->reply);
> }
> - FREE(inbuf);
> +
> + set_client_state(c, CLT_RECV);
> }
>
> /*
> @@ -553,6 +611,8 @@ void *uxsock_listen(long ux_sock, void *trigger_data)
> continue;
> }
> handle_client(c, trigger_data);
> + if (c->error == -ECONNRESET)
> + dead_client(c);
> }
> }
> /* see if we got a non-fatal signal */
> --
> 2.33.0
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://listman.redhat.com/mailman/listinfo/dm-devel
