From 173b80e8f8103f26438d344e9b97335d4e5036b4 Mon Sep 17 00:00:00 2001 From: Michal Privoznik Date: Thu, 11 Jun 2020 16:43:22 +0200 Subject: [PATCH 2/6] leaseshelper: Wait to acquire PID file MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On a DHCP transaction, dnsmasq runs our leases helper which updates corresponding JSON files. While one dnsmasq won't run the leaseshelper in parallel, two dnsmasqs (from two distinct networks) might. To avoid corrupting JSON file, the leaseshelper acquires PID file first. Well, the way it's acquiring it is not ideal - it calls virPidFileAcquirePath(wait = false); which means, that either it acquires the PID file instantly or returns an error and does not touch the JSON at all. This in turn means that there might be a leases record missing. With wait = true, this won't happen. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1840307 cherry pick from: 876211ef4a192df1603b45715044ec14567d7e9f Signed-off-by: Michal Privoznik Reviewed-by: Daniel P. Berrangé --- src/network/leaseshelper.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/network/leaseshelper.c b/src/network/leaseshelper.c index a1780ca..86c847d 100644 --- a/src/network/leaseshelper.c +++ b/src/network/leaseshelper.c @@ -160,7 +160,7 @@ main(int argc, char **argv) pid_file = g_strdup(RUNSTATEDIR "/leaseshelper.pid"); /* Try to claim the pidfile, exiting if we can't */ - if ((pid_file_fd = virPidFileAcquirePath(pid_file, false, getpid())) < 0) + if ((pid_file_fd = virPidFileAcquirePath(pid_file, true, getpid())) < 0) goto cleanup; /* Since interfaces can be hot plugged, we need to make sure that the -- 1.8.3.1