[dm-devel] [PATCH 30/35] multipathd: uxlsnr: merge uxsock_trigger() into state machine
mwilck at suse.com
mwilck at suse.com
Fri Sep 10 11:41:15 UTC 2021
From: Martin Wilck <mwilck at suse.com>
This patch sets up the bulk of the state machine. The idea is to
fall through the case labels as long as possible (when steps succeed)
and return to the caller if either an error occurs, or it becomes
necessary to wait for some pollable condition.
While doing this, switch to negative error codes for the functions
in uxlsnr.c (e.g. parse_cmd()). Positive return codes are reserved
for the cli_handler functions themselves. This way we can clearly
distinguish the error source, and avoid confusion and misleading
error messages. No cli_handler returns negative values.
Note: with this patch applied, clients may hang and time out if
the handler fails to acquire the vecs lock. This will be fixed in the
follow-up patch "multipathd: uxlsnr: add idle notification".
Signed-off-by: Martin Wilck <mwilck at suse.com>
---
multipathd/uxlsnr.c | 145 ++++++++++++++++++++++++--------------------
1 file changed, 80 insertions(+), 65 deletions(-)
diff --git a/multipathd/uxlsnr.c b/multipathd/uxlsnr.c
index ff9604f..553274b 100644
--- a/multipathd/uxlsnr.c
+++ b/multipathd/uxlsnr.c
@@ -299,22 +299,13 @@ static int parse_cmd(struct client *c)
r = get_cmdvec(c->cmd, &c->cmdvec);
- if (r) {
- genhelp_handler(c->cmd, r, &c->reply);
- if (get_strbuf_len(&c->reply) == 0)
- return EINVAL;
- return 0;
- }
+ if (r)
+ return -r;
c->handler = find_handler_for_cmdvec(c->cmdvec);
- if (!c->handler || !c->handler->fn) {
- genhelp_handler(c->cmd, EINVAL, &c->reply);
- if (get_strbuf_len(&c->reply) == 0)
- r = EINVAL;
- else
- r = 0;
- }
+ if (!c->handler || !c->handler->fn)
+ return -EINVAL;
return r;
}
@@ -325,7 +316,7 @@ static int execute_handler(struct client *c, struct vectors *vecs, int timeout)
struct timespec tmo;
if (!c->handler)
- return EINVAL;
+ return -EINVAL;
if (clock_gettime(CLOCK_REALTIME, &tmo) == 0) {
tmo.tv_sec += timeout;
@@ -355,50 +346,29 @@ static int execute_handler(struct client *c, struct vectors *vecs, int timeout)
return r;
}
-static int uxsock_trigger(struct client *c, void *trigger_data)
+void default_reply(struct client *c, int r)
{
- struct vectors * vecs;
- int r = 1;
-
- vecs = (struct vectors *)trigger_data;
-
- r = parse_cmd(c);
-
- if (r == 0 && c->cmdvec && VECTOR_SIZE(c->cmdvec) > 0) {
- struct key *kw = VECTOR_SLOT(c->cmdvec, 0);
-
- if (!c->is_root && kw->code != LIST)
- r = EPERM;
- }
-
- if (r == 0 && c->handler)
- r = execute_handler(c, vecs, uxsock_timeout / 1000);
-
- if (c->cmdvec) {
- free_keys(c->cmdvec);
- c->cmdvec = NULL;
- }
-
- if (r > 0) {
- switch(r) {
- case ETIMEDOUT:
- append_strbuf_str(&c->reply, "timeout\n");
- break;
- case EPERM:
- append_strbuf_str(&c->reply,
- "permission deny: need to be root\n");
- break;
- default:
- append_strbuf_str(&c->reply, "fail\n");
- break;
- }
- }
- else if (!r && get_strbuf_len(&c->reply) == 0) {
+ switch(r) {
+ case -EINVAL:
+ case -ESRCH:
+ case -ENOMEM:
+ /* return codes from get_cmdvec() */
+ genhelp_handler(c->cmd, r, &c->reply);
+ break;
+ case -EPERM:
+ append_strbuf_str(&c->reply,
+ "permission deny: need to be root\n");
+ break;
+ case -ETIMEDOUT:
+ append_strbuf_str(&c->reply, "timeout\n");
+ break;
+ case 0:
append_strbuf_str(&c->reply, "ok\n");
- r = 0;
+ break;
+ default:
+ append_strbuf_str(&c->reply, "fail\n");
+ break;
}
- /* else if (r < 0) leave *reply alone */
- return r;
}
static void set_client_state(struct client *c, int state)
@@ -409,6 +379,7 @@ static void set_client_state(struct client *c, int state)
reset_strbuf(&c->reply);
memset(c->cmd, '\0', sizeof(c->cmd));
c->expires = ts_zero;
+ c->error = 0;
/* fallthrough */
case CLT_SEND:
/* reuse these fields for next data transfer */
@@ -420,10 +391,13 @@ static void set_client_state(struct client *c, int state)
c->state = state;
}
-static void handle_client(struct client *c, void *trigger_data)
+static void handle_client(struct client *c, struct vectors *vecs)
{
ssize_t n;
+ condlog(4, "%s: cli[%d] state=%d cmd=\"%s\" repl \"%s\"", __func__,
+ c->fd, c->state, c->cmd, get_strbuf_str(&c->reply));
+
switch (c->state) {
case CLT_RECV:
if (c->cmd_len == 0) {
@@ -464,15 +438,52 @@ static void handle_client(struct client *c, void *trigger_data)
return;
set_client_state(c, CLT_PARSE);
}
- break;
- default:
- break;
- }
+ condlog(4, "cli[%d]: Got request [%s]", c->fd, c->cmd);
+ /* fallthrough */
- condlog(4, "cli[%d]: Got request [%s]", c->fd, c->cmd);
- uxsock_trigger(c, trigger_data);
+ case CLT_PARSE:
+ condlog(4, "%s: cli[%d] state=%d cmd=\"%s\" repl \"%s\"", __func__,
+ c->fd, c->state, c->cmd, get_strbuf_str(&c->reply));
+ c->error = parse_cmd(c);
+
+ /* Permission check */
+ if (c->error == 0 && c->cmdvec && VECTOR_SIZE(c->cmdvec) > 0) {
+ struct key *kw = VECTOR_SLOT(c->cmdvec, 0);
+
+ if (!c->is_root && kw->code != LIST) {
+ /* this will fall through to CLT_SEND */
+ c->error = -EPERM;
+ condlog(0, "%s: cli[%d]: unauthorized cmd \"%s\"",
+ __func__, c->fd, c->cmd);
+ }
+ }
+ set_client_state(c, CLT_WAIT_LOCK);
+ /* fallthrough */
+
+ case CLT_WAIT_LOCK:
+ condlog(4, "%s: cli[%d] state=%d cmd=\"%s\" repl \"%s\"", __func__,
+ c->fd, c->state, c->cmd, get_strbuf_str(&c->reply));
+ /* tbd */
+ set_client_state(c, CLT_WORK);
+ /* fallthrough */
+
+ case CLT_WORK:
+ condlog(4, "%s: cli[%d] state=%d cmd=\"%s\" repl \"%s\"", __func__,
+ c->fd, c->state, c->cmd, get_strbuf_str(&c->reply));
+ if (c->error == 0 && c->handler)
+ c->error = execute_handler(c, vecs, uxsock_timeout / 1000);
+
+ if (c->cmdvec) {
+ free_keys(c->cmdvec);
+ c->cmdvec = NULL;
+ }
+ set_client_state(c, CLT_SEND);
+ /* fallthrough */
+
+ case CLT_SEND:
+ if (get_strbuf_len(&c->reply) == 0)
+ default_reply(c, c->error);
- if (get_strbuf_len(&c->reply) > 0) {
const char *buf = get_strbuf_str(&c->reply);
if (send_packet(c->fd, buf) != 0)
@@ -481,9 +492,13 @@ static void handle_client(struct client *c, void *trigger_data)
condlog(4, "cli[%d]: Reply [%zu bytes]", c->fd,
get_strbuf_len(&c->reply) + 1);
reset_strbuf(&c->reply);
- }
- set_client_state(c, CLT_RECV);
+ set_client_state(c, CLT_RECV);
+ break;
+
+ default:
+ break;
+ }
}
/*
--
2.33.0
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