@@ -, +, @@ 
 causes deadlocks (#19914)
---
 configure.ac               | 5 +++++
 mono/utils/mono-os-mutex.h | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)
--- a/configure.ac	
+++ a/configure.ac	
@@ -320,6 +320,11 @@ case "$host" in
                 	# available during cross-compilation
                 	mono_cv_uscore=no
                 fi
+                case "$host" in
+                *-musl)
+                        AC_DEFINE(MUSL, 1, [musl libc])
+                        ;;
+                esac
 		case "$host" in
 		*-tizen-linux-*)
 			platform_tizen=yes
--- a/mono/utils/mono-os-mutex.h	
+++ a/mono/utils/mono-os-mutex.h	
@@ -59,7 +59,7 @@ mono_os_mutex_init_type (mono_mutex_t *mutex, int type)
 	if (G_UNLIKELY (res != 0))
 		g_error ("%s: pthread_mutexattr_settype failed with \"%s\" (%d)", __func__, g_strerror (res), res);
 
-#if !defined(__HAIKU__) && defined (PTHREAD_PRIO_INHERIT) && HAVE_DECL_PTHREAD_MUTEXATTR_SETPROTOCOL
+#if !defined(__HAIKU__) && !defined(MUSL) && defined (PTHREAD_PRIO_INHERIT) && HAVE_DECL_PTHREAD_MUTEXATTR_SETPROTOCOL
 	/* use PTHREAD_PRIO_INHERIT if possible */
 	res = pthread_mutexattr_setprotocol (&attr, PTHREAD_PRIO_INHERIT);
 	if (G_UNLIKELY (res != 0 && res != ENOTSUP))