From: Willy Tarreau <w@1wt.eu>
Date: Tue, 11 Aug 2026 11:56:44 +0000 (+0200)
Subject: MINOR: debug: force complain's backtrace to be a tail jump instead of a tail call
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=431b6b1cd92a54f4a53b66a5ff27a64381ff9a23;p=thirdparty%2Fhaproxy.git

MINOR: debug: force complain's backtrace to be a tail jump instead of a tail call

We can make complain_with_dbg() and complain() disappear from the
backtrace by forcing tail call elimination on these functions, since
ha_backtrace_to_stderr() is called last and with a compatible return
code.

Thanks to this, backtraces are clean again:

  WARNING: check condition "one > zero" matched at src/debug.c:1170 (please report to developers)
  This was triggered on purpose from the CLI 'debug dev check' command.
    call trace(13):
    |       0x6ea2c0 <09 9a 00 e8 b0 ef ff ff]: debug_parse_cli_check+0x40/0x42 > complain_with_dbg
    |       0x69724a <bd a8 fd ff ff 41 ff d0]: main+0x25154a
    |       0x69863c <00 00 00 e8 44 e9 ff ff]: cli_io_handler+0x54c/0xdee > main+0x251280
    |       0x710830 <00 0f 29 45 c0 ff 52 18]: task_process_applet+0x340/0xd84
    |       0x7b595b <00 00 4c 89 d7 41 ff d1]: run_tasks_from_lists+0x43b/0xbdb
    |       0x7b651a <8d 7d b0 e8 06 f0 ff ff]: process_runnable_tasks+0x41a/0xaae > run_tasks_from_lists
    |       0x70344e <01 00 00 e8 b2 2c 0b 00]: run_poll_loop+0xae/0x522 > process_runnable_tasks
    |       0x703b4f <00 00 00 e8 51 f8 ff ff]: run_thread_poll_loop+0x27f/0x4ba > run_poll_loop
    |       0x44703f <46 b2 00 e8 91 c8 2b 00]: main+0x133f/0x1d75 > run_thread_poll_loop
---

diff --git a/src/debug.c b/src/debug.c
index 0b15465b2..20b15a761 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -1094,7 +1094,7 @@ static void _complain(uint details, const char *msg, struct debug_count *dbg)
 }
 
 /* the exported function */
-void complain(uint details, const char *msg)
+eliminate_tail_calls void complain(uint details, const char *msg)
 {
 	_complain(details, msg, NULL);
 
@@ -1106,7 +1106,7 @@ void complain(uint details, const char *msg)
 }
 
 /* the same, for use with a debug_count struct */
-void complain_with_dbg(struct debug_count *dbg)
+eliminate_tail_calls void complain_with_dbg(struct debug_count *dbg)
 {
 	if (_HA_ATOMIC_FETCH_ADD(&dbg->count, 1) && dbg->type == DBG_BUG_ONCE)
 		return;