| Message ID | 20211127151929.7727-34-mwilck@suse.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | christophe varoqui |
| Headers | show |
| Series | multipathd: uxlsnr overhaul | expand |
On Sat, Nov 27, 2021 at 04:19:26PM +0100, mwilck@suse.com wrote: > From: Martin Wilck <mwilck@suse.com> > > 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@suse.com> Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com> > --- > 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@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel
Hi Ben, On Mon, 2021-11-29 at 14:29 -0600, Benjamin Marzinski wrote: > On Sat, Nov 27, 2021 at 04:19:26PM +0100, mwilck@suse.com wrote: > > From: Martin Wilck <mwilck@suse.com> > > > > 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@suse.com> > Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com> Thanks. I think we're good for a submission to Christophe. I'd like you to review 12/13 and 13/13 of my latest series though, as they fix actual bugs in the current code. You're of course welcome to review more, too ;-), but if these two are good, I believe we should move forward. Regards Martin -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel
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;