From 469fa2c9d9dfc4ec08dc2555f18c89587411716f Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Tue, 14 May 2019 17:27:52 +0200 Subject: [PATCH] MINOR: debug: add a new BUG_ON macro We do have some code paths testing for impossible errors that tend to be quite confusing, first for maintenance (what to do on such errors, and how far to guess the bug), second for developers as it tends to hide the main purpose and expectations of these call places. Also most of the time impossible errors are ignored by the callers so the tests are not even usable during debugging. Let's instead implement a BUG_ON macro which takes a condition, which if true, will cause a message to be emitted and optionally to crash the process. Additionally, these calls inserted at various places server as hints and documentation for developers to know that such conditions must absolutely not happen. This is only enabled when DEBUG_STRICT or DEBUG_STRICT_NOCRASH are set. As its name implies, DEBUG_STRICT_NOCRASH only performs the test but does not crash, which can be useful to track some checkpoints. At the moment nothing uses this code. --- include/common/debug.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/include/common/debug.h b/include/common/debug.h index 8f6d123425..014e5eeb8f 100644 --- a/include/common/debug.h +++ b/include/common/debug.h @@ -42,6 +42,32 @@ */ #define ABORT_NOW() (*(volatile int*)1=0) +/* BUG_ON: complains if is true when DEBUG_STRICT or DEBUG_STRICT_NOCRASH + * are set, does nothing otherwise. With DEBUG_STRICT in addition it immediately + * crashes using ABORT_NOW() above. + */ +#if defined(DEBUG_STRICT) || defined(DEBUG_STRICT_NOCRASH) +#if defined(DEBUG_STRICT) +#define CRASH_NOW() ABORT_NOW() +#else +#define CRASH_NOW() +#endif + +#define BUG_ON(cond) _BUG_ON(cond, __FILE__, __LINE__) +#define _BUG_ON(cond, file, line) __BUG_ON(cond, file, line) +#define __BUG_ON(cond, file, line) \ + do { \ + if (unlikely(cond)) { \ + const char msg[] = "\nFATAL: bug condition \"" #cond "\" matched at " file ":" #line "\n"; \ + (void)write(2, msg, strlen(msg)); \ + CRASH_NOW(); \ + } \ + } while (0) +#else +#undef CRASH_NOW +#define BUG_ON(cond) +#endif + /* this one is provided for easy code tracing. * Usage: TRACE(strm||0, fmt, args...); * TRACE(strm, "");