tree 7f95f7f11fe9386b2775d7ddfa35bfe5c7f356b2
parent 0179e1d7aa4a15b5325e8e3744ef302a488893d6
author Amaury Denoyelle <adenoyelle@haproxy.com> 1621241238 +0200
committer Christopher Faulet <cfaulet@haproxy.com> 1622452503 +0200

BUG/MAJOR: server: prevent deadlock when using 'set maxconn server'

A deadlock is possible with 'set maxconn server' command, if there is
pending connection ready to be dequeued. This is caused by the locking
of server spinlock in both cli_parse_set_maxconn_server and
process_srv_queue.

Fix this by reducing the scope of the server lock into
server_parse_maxconn_change_request. If connection are dequeued, the
lock is taken a second time. This can be seen as suboptimal but as it
happens only during 'set maxconn server' it can be considered as
tolerable.

This issue was reported on the mailing list, for the 1.8.x branch.
It must be backported up to the 1.8.

(cherry picked from commit 79a88ba3d09f7e2b73ae27cb5d24cc087a548fa6)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>