From eb4713c8e55917485660ed56e8a009a558454f54 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20K=C4=99pie=C5=84?= <michal@isc.org>
Date: Thu, 9 Dec 2021 14:02:36 +0100
Subject: [PATCH] Remove mutex debugging code

Mutex debugging code (used when the ISC_MUTEX_DEBUG preprocessor macro
is set to 1 and PTHREAD_MUTEX_ERRORCHECK is defined) has been broken for
the past 3 years (since commit 2f3eee5a4fdad6606135116c70875b3180c7ed83)
and nobody complained, which is a strong indication that this code is
not being used these days any more.  External tools for detecting
locking issues are already wired into various GitLab CI checks.  Drop
all code depending on the ISC_MUTEX_DEBUG preprocessor macro being set.
---
 lib/isc/include/isc/mutex.h | 26 ++-------------------
 lib/isc/mutex.c             | 46 +------------------------------------
 2 files changed, 3 insertions(+), 69 deletions(-)

diff --git a/lib/isc/include/isc/mutex.h b/lib/isc/include/isc/mutex.h
index d930a180e3..f74f7335ae 100644
--- a/lib/isc/include/isc/mutex.h
+++ b/lib/isc/include/isc/mutex.h
@@ -21,31 +21,12 @@
 
 ISC_LANG_BEGINDECLS
 
-/*!
- * Supply mutex attributes that enable deadlock detection
- * (helpful when debugging).  This is system dependent and
- * currently only supported on NetBSD.
- */
-#if ISC_MUTEX_DEBUG && defined(__NetBSD__) && defined(PTHREAD_MUTEX_ERRORCHECK)
-extern pthread_mutexattr_t isc__mutex_attrs;
-#define ISC__MUTEX_ATTRS &isc__mutex_attrs
-#else /* if ISC_MUTEX_DEBUG && defined(__NetBSD__) && \
-       * defined(PTHREAD_MUTEX_ERRORCHECK) */
-#define ISC__MUTEX_ATTRS NULL
-#endif /* if ISC_MUTEX_DEBUG && defined(__NetBSD__) && \
-	* defined(PTHREAD_MUTEX_ERRORCHECK) */
-
-/* XXX We could do fancier error handling... */
-
 typedef pthread_mutex_t isc_mutex_t;
 
-#if ISC_MUTEX_DEBUG && defined(PTHREAD_MUTEX_ERRORCHECK)
-#define isc_mutex_init(mp) isc_mutex_init_errcheck((mp))
-#else /* if ISC_MUTEX_DEBUG && defined(PTHREAD_MUTEX_ERRORCHECK) */
-#define isc_mutex_init(mp) isc__mutex_init((mp), __FILE__, __LINE__)
 void
 isc__mutex_init(isc_mutex_t *mp, const char *file, unsigned int line);
-#endif /* if ISC_MUTEX_DEBUG && defined(PTHREAD_MUTEX_ERRORCHECK) */
+
+#define isc_mutex_init(mp) isc__mutex_init((mp), __FILE__, __LINE__)
 
 #define isc_mutex_lock(mp) \
 	((pthread_mutex_lock((mp)) == 0) ? ISC_R_SUCCESS : ISC_R_UNEXPECTED)
@@ -58,7 +39,4 @@ isc__mutex_init(isc_mutex_t *mp, const char *file, unsigned int line);
 
 #define isc_mutex_destroy(mp) RUNTIME_CHECK(pthread_mutex_destroy((mp)) == 0)
 
-void
-isc_mutex_init_errcheck(isc_mutex_t *mp);
-
 ISC_LANG_ENDDECLS
diff --git a/lib/isc/mutex.c b/lib/isc/mutex.c
index 562dedcffe..70ea5359bb 100644
--- a/lib/isc/mutex.c
+++ b/lib/isc/mutex.c
@@ -24,54 +24,11 @@
 #include <isc/string.h>
 #include <isc/util.h>
 
-#if ISC_MUTEX_DEBUG && defined(PTHREAD_MUTEX_ERRORCHECK)
-
-static bool errcheck_initialized = false;
-static pthread_mutexattr_t errcheck;
-static isc_once_t once_errcheck = ISC_ONCE_INIT;
-
-static void
-initialize_errcheck(void) {
-	RUNTIME_CHECK(pthread_mutexattr_init(&errcheck) == 0);
-	RUNTIME_CHECK(pthread_mutexattr_settype(&errcheck,
-						PTHREAD_MUTEX_ERRORCHECK) == 0);
-	errcheck_initialized = true;
-}
-
-void
-isc_mutex_init_errcheck(isc_mutex_t *mp) {
-	isc_result_t result;
-	int err;
-
-	result = isc_once_do(&once_errcheck, initialize_errcheck);
-	RUNTIME_CHECK(result == ISC_R_SUCCESS);
-
-	err = pthread_mutex_init(mp, &errcheck);
-	if (err != 0) {
-		strerror_r(err, strbuf, sizeof(strbuf));
-		isc_error_fatal(file, line, "pthread_mutex_init failed: %s",
-				strbuf);
-	}
-}
-#endif /* if ISC_MUTEX_DEBUG && defined(PTHREAD_MUTEX_ERRORCHECK) */
-
-#if ISC_MUTEX_DEBUG && defined(__NetBSD__) && defined(PTHREAD_MUTEX_ERRORCHECK)
-pthread_mutexattr_t isc__mutex_attrs = {
-	PTHREAD_MUTEX_ERRORCHECK, /* m_type */
-	0			  /* m_flags, which appears to be unused. */
-};
-#endif /* if ISC_MUTEX_DEBUG && defined(__NetBSD__) && \
-	* defined(PTHREAD_MUTEX_ERRORCHECK) */
-
-#if !(ISC_MUTEX_DEBUG && defined(PTHREAD_MUTEX_ERRORCHECK))
-
 #ifdef HAVE_PTHREAD_MUTEX_ADAPTIVE_NP
 static bool attr_initialized = false;
 static pthread_mutexattr_t attr;
 static isc_once_t once_attr = ISC_ONCE_INIT;
-#endif /* HAVE_PTHREAD_MUTEX_ADAPTIVE_NP */
 
-#ifdef HAVE_PTHREAD_MUTEX_ADAPTIVE_NP
 static void
 initialize_attr(void) {
 	RUNTIME_CHECK(pthread_mutexattr_init(&attr) == 0);
@@ -92,7 +49,7 @@ isc__mutex_init(isc_mutex_t *mp, const char *file, unsigned int line) {
 
 	err = pthread_mutex_init(mp, &attr);
 #else  /* HAVE_PTHREAD_MUTEX_ADAPTIVE_NP */
-	err = pthread_mutex_init(mp, ISC__MUTEX_ATTRS);
+	err = pthread_mutex_init(mp, NULL);
 #endif /* HAVE_PTHREAD_MUTEX_ADAPTIVE_NP */
 	if (err != 0) {
 		char strbuf[ISC_STRERRORSIZE];
@@ -101,4 +58,3 @@ isc__mutex_init(isc_mutex_t *mp, const char *file, unsigned int line) {
 				strbuf);
 	}
 }
-#endif /* if !(ISC_MUTEX_DEBUG && defined(PTHREAD_MUTEX_ERRORCHECK)) */