proxy: fix crash when backensd are gc'd

crept in on an earlier cleanup commit. for some reason pools get gc'ed
pretty quickly but backends take several HUP's so I didn't see this
until I sat here HUP'ing the proxy 10+ times in a row.

1 files changed, 4 insertions, 2 deletions

diff --git a/proxy_lua.c b/proxy_lua.c
index 8531f03..495c0de 100644
--- a/proxy_lua.c
+++ b/proxy_lua.c
@@ -96,10 +96,12 @@ static int mcplib_backend_gc(lua_State *L) {
     assert(STAILQ_EMPTY(&be->io_head));
 
     mcmc_disconnect(be->client);
-    free(be->client);
 
-    proxy_ctx_t *ctx = lua_touserdata(L, lua_upvalueindex(MCP_CONTEXT_UPVALUE));
+    // FIXME (v2): can we ensure a backend always has be->event_thread set, so
+    // we can use be->event_thread->ctx?
+    proxy_ctx_t *ctx = settings.proxy_ctx;
     STAT_DECR(ctx, backend_total, 1);
+    free(be->client);
 
     return 0;
 }