From 1405c6d998d78c7756bb5519cb69d2582f583475 Mon Sep 17 00:00:00 2001 From: phk Date: Tue, 7 Aug 2007 10:27:34 +0000 Subject: [PATCH] Minimize a race when looking up addresses for backends. The race is not closed however, proper locking needs to be thought out. An XXX comment documents this for now. git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@1809 d4fa192b-c00b-0410-8231-f00ffab90ce4 --- varnish-cache/bin/varnishd/cache_backend.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/varnish-cache/bin/varnishd/cache_backend.c b/varnish-cache/bin/varnishd/cache_backend.c index 0e929762..ed2a23ef 100644 --- a/varnish-cache/bin/varnishd/cache_backend.c +++ b/varnish-cache/bin/varnishd/cache_backend.c @@ -116,20 +116,20 @@ vbe_new_conn(void) return (vbc); } -/*--------------------------------------------------------------------*/ +/*-------------------------------------------------------------------- + * XXX: There is a race here, we need to lock the replacement of the + * XXX: resolved addresses, or some other thread might try to access + * XXX: them while/during/after we changed them. + * XXX: preferably, we should make a copy to the vbe while we hold a + * XXX: lock anyway. + */ static void vbe_lookup(struct backend *bp) { - struct addrinfo *res, hint; + struct addrinfo *res, hint, *old; int error; - if (bp->addr != NULL) { - freeaddrinfo(bp->addr); - bp->addr = NULL; - bp->last_addr = NULL; - } - memset(&hint, 0, sizeof hint); hint.ai_family = PF_UNSPEC; hint.ai_socktype = SOCK_STREAM; @@ -144,8 +144,11 @@ vbe_lookup(struct backend *bp) printf("getaddrinfo: %s\n", gai_strerror(error)); /* XXX */ return; } + old = bp->addr; bp->last_addr = res; bp->addr = res; + if (old != NULL) + freeaddrinfo(old); } /*--------------------------------------------------------------------*/ -- 2.39.5