From 3b9f7300b012805beaa6e0f01fcfde2ddcfe6b01 Mon Sep 17 00:00:00 2001
From: dormando <dormando@rydia.net>
Date: Fri, 20 Jan 2023 16:02:53 -0800
Subject: proxy: fix stats deadlock caused by await code

- specifically the WSTAT_DECR in proxy_await.c's return code could
  potentially use the wrong thread's lock

This is why I've been swapping c with thread as lock/function arguments
all over the code lately; it's very accident prone.

Am reasonably sure this causes the deadlock but need to attempt to
verify more.
---
 proto_proxy.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

(limited to 'proto_proxy.c')

diff --git a/proto_proxy.c b/proto_proxy.c
index 7cea462..b09e113 100644
--- a/proto_proxy.c
+++ b/proto_proxy.c
@@ -402,7 +402,7 @@ void proxy_cleanup_conn(conn *c) {
     lua_State *L = thr->L;
     luaL_unref(L, LUA_REGISTRYINDEX, c->proxy_coro_ref);
     c->proxy_coro_ref = 0;
-    WSTAT_DECR(c, proxy_req_active, 1);
+    WSTAT_DECR(thr, proxy_req_active, 1);
 }
 
 // we buffered a SET of some kind.
@@ -545,7 +545,7 @@ int proxy_run_coroutine(lua_State *Lc, mc_resp *resp, io_pending_proxy_t *p, con
     size_t rlen = 0;
 
     if (cores == LUA_OK) {
-        WSTAT_DECR(c, proxy_req_active, 1);
+        WSTAT_DECR(c->thread, proxy_req_active, 1);
         int type = lua_type(Lc, 1);
         if (type == LUA_TUSERDATA) {
             mcp_resp_t *r = luaL_checkudata(Lc, 1, "mcp.response");
@@ -619,7 +619,7 @@ int proxy_run_coroutine(lua_State *Lc, mc_resp *resp, io_pending_proxy_t *p, con
         }
 
     } else {
-        WSTAT_DECR(c, proxy_req_active, 1);
+        WSTAT_DECR(c->thread, proxy_req_active, 1);
         P_DEBUG("%s: Failed to run coroutine: %s\n", __func__, lua_tostring(Lc, -1));
         LOGGER_LOG(NULL, LOG_PROXYEVENTS, LOGGER_PROXY_ERROR, NULL, lua_tostring(Lc, -1));
         proxy_out_errstring(resp, "lua failure");
@@ -642,7 +642,7 @@ static void proxy_process_command(conn *c, char *command, size_t cmdlen, bool mu
     // permanent solution.
     int ret = process_request(&pr, command, cmdlen);
     if (ret != 0) {
-        WSTAT_INCR(c, proxy_conn_errors, 1);
+        WSTAT_INCR(c->thread, proxy_conn_errors, 1);
         if (!resp_start(c)) {
             conn_set_state(c, conn_closing);
             return;
@@ -749,7 +749,7 @@ static void proxy_process_command(conn *c, char *command, size_t cmdlen, bool mu
     // We test the command length all the way down here because multigets can
     // be very long, and they're chopped up by now.
     if (cmdlen >= MCP_REQUEST_MAXLEN) {
-        WSTAT_INCR(c, proxy_conn_errors, 1);
+        WSTAT_INCR(c->thread, proxy_conn_errors, 1);
         if (!resp_start(c)) {
             conn_set_state(c, conn_closing);
             return;
@@ -797,7 +797,7 @@ static void proxy_process_command(conn *c, char *command, size_t cmdlen, bool mu
         if (c->item == NULL) {
             lua_settop(L, 0);
             proxy_out_errstring(c->resp, "out of memory");
-            WSTAT_DECR(c, proxy_req_active, 1);
+            WSTAT_DECR(c->thread, proxy_req_active, 1);
             return;
         }
         c->item_malloced = true;
@@ -864,7 +864,7 @@ static void mcp_queue_io(conn *c, mc_resp *resp, int coro_ref, lua_State *Lc) {
 
     io_pending_proxy_t *p = do_cache_alloc(c->thread->io_cache);
     if (p == NULL) {
-        WSTAT_INCR(c, proxy_conn_oom, 1);
+        WSTAT_INCR(c->thread, proxy_conn_oom, 1);
         proxy_lua_error(Lc, "out of memory allocating from IO cache");
         return;
     }
-- 
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