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BUG/MEDIUM: cli: Deadlock when setting frontend maxconn

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The proxy lock state isn't passed down to relax_listener
through dequeue_proxy_listeners, which causes a deadlock
in relax_listener when it tries to get that lock.

Backporting: Older versions didn't have relax_listener and directly called
resume_listener in dequeue_proxy_listeners. lpx should just be passed directly
to resume_listener then.

The bug was introduced in commit 001328873c352e5e4b1df0dcc8facaf2fc1408aa

[cf: This patch should fix the issue #2726. It must be backported as far as
2.4]

(cherry picked from commit a889413f5ec5e2c0c6ed30debfd16f666dbc0f99)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
This commit is contained in:
Oliver Dala 2024-09-25 11:37:25 +02:00 committed by Christopher Faulet
parent 7ba52732e4
commit dcd946dcde
3 changed files with 12 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/haproxy/listener.h
View File

@ -94,7 +94,7 @@ void enable_listener(struct listener *listener);
void dequeue_all_listeners(void);
/* Dequeues all listeners waiting for a resource in proxy <px>'s queue */
void dequeue_proxy_listeners(struct proxy *px);
void dequeue_proxy_listeners(struct proxy *px, int lpx);
/* This function closes the listening socket for the specified listener,
* provided that it's already in a listening state. The listener enters the

14
src/listener.c
View File

@ -707,8 +707,12 @@ void dequeue_all_listeners()
}
}
/* Dequeues all listeners waiting for a resource in proxy <px>'s queue */
void dequeue_proxy_listeners(struct proxy *px)
/* Dequeues all listeners waiting for a resource in proxy <px>'s queue
* The caller is responsible for indicating in lpx, whether the proxy's lock
* is already held (non-zero) or not (zero) so that this information can be
* passed to relax_listener
*/
void dequeue_proxy_listeners(struct proxy *px, int lpx)
{
struct listener *listener;
@ -716,7 +720,7 @@ void dequeue_proxy_listeners(struct proxy *px)
/* This cannot fail because the listeners are by definition in
* the LI_LIMITED state.
*/
relax_listener(listener, 0, 0);
relax_listener(listener, lpx, 0);
}
}
@ -1558,7 +1562,7 @@ void listener_accept(struct listener *l)
if (p && !MT_LIST_ISEMPTY(&p->listener_queue) &&
(!p->fe_sps_lim || freq_ctr_remain(&p->fe_counters.sess_per_sec, p->fe_sps_lim, 0) > 0))
dequeue_proxy_listeners(p);
dequeue_proxy_listeners(p, 0);
}
return;
@ -1617,7 +1621,7 @@ void listener_release(struct listener *l)
if (fe && !MT_LIST_ISEMPTY(&fe->listener_queue) &&
(!fe->fe_sps_lim || freq_ctr_remain(&fe->fe_counters.sess_per_sec, fe->fe_sps_lim, 0) > 0))
dequeue_proxy_listeners(fe);
dequeue_proxy_listeners(fe, 0);
else {
unsigned int wait;
int expire = TICK_ETERNITY;

4
src/proxy.c
View File

@ -1984,7 +1984,7 @@ struct task *manage_proxy(struct task *t, void *context, unsigned int state)
}
/* The proxy is not limited so we can re-enable any waiting listener */
dequeue_proxy_listeners(p);
dequeue_proxy_listeners(p, 0);
out:
t->expire = next;
task_queue(t);
@ -2995,7 +2995,7 @@ static int cli_parse_set_maxconn_frontend(char **args, char *payload, struct app
}
if (px->maxconn > px->feconn)
dequeue_proxy_listeners(px);
dequeue_proxy_listeners(px, 1);
HA_RWLOCK_WRUNLOCK(PROXY_LOCK, &px->lock);