BUG/MINOR: hlua: improper lock usage in hlua_filter_new()

In hlua_filter_new(), after each hlua resume, we systematically try to
empty the stack by calling lua_settop(). However we're doing this without
locking the lua context, so it is unsafe in multithreading context if the
script is loaded using 'lua-load'. To fix the issue, we protect the call
with hlua_{lock,unlock}() helpers.

This should be backported up to 2.6.

diff --git a/src/hlua.c b/src/hlua.c
index 1b86e91992993e3a89ac7c9e184eb082a4819fe1..2339711a38af2f7b372f1107a458f247feb85cea 100644 (file)
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -11956,8 +11956,11 @@ static int hlua_filter_new(struct stream *s, struct filter *filter)
        }
 
   end:
-       if (s->hlua)
+       if (s->hlua) {
+               hlua_lock(s->hlua);
                lua_settop(s->hlua->T, 0);
+               hlua_unlock(s->hlua);
+       }
        if (ret <= 0) {
                if (flt_ctx) {
                        hlua_ctx_destroy(flt_ctx->hlua[0]);