compiler: fix thread_local detection

configure.ac

@@ -629,7 +629,7 @@ AC_CHECK_DECLS([PR_SET_NO_NEW_PRIVS], [], [], [#include <sys/prctl.h>])
 AC_CHECK_DECLS([PR_GET_NO_NEW_PRIVS], [], [], [#include <sys/prctl.h>])
 
 # Check for some headers
-AC_CHECK_HEADERS([pty.h sys/memfd.h sys/personality.h sys/resource.h sys/signalfd.h sys/timerfd.h utmpx.h threads.h])
+AC_CHECK_HEADERS([pty.h sys/memfd.h sys/personality.h sys/resource.h sys/signalfd.h sys/timerfd.h utmpx.h])
 
 AC_CHECK_HEADER([ifaddrs.h],
 	AM_CONDITIONAL(HAVE_IFADDRS_H, true)

src/lxc/compiler.h

@@ -12,23 +12,14 @@
 
 #include "config.h"
 
-#if defined(HAVE_THREADS_H)
-	#include <threads.h>
-	#define THREAD_LOCAL_STORAGE_SUPPORTED
-#elif defined(thread_local)
-	#define THREAD_LOCAL_STORAGE_SUPPORTED
+#ifndef thread_local
+#if __STDC_VERSION__ >= 201112L &&    \
+    !(defined(__STDC_NO_THREADS__) || \
+      (defined(__GNU_LIBRARY__) && __GLIBC__ == 2 && __GLIBC_MINOR__ < 16))
+#define thread_local _Thread_local
 #else
-	#if __STDC_VERSION__ >= 201112L &&    \
-	    !(defined(__STDC_NO_THREADS__) || \
-	      (defined(__GNU_LIBRARY__) && __GLIBC__ == 2 && __GLIBC_MINOR__ < 16))
-		#define thread_local _Thread_local
-
-		#define THREAD_LOCAL_STORAGE_SUPPORTED
-	#else
-		#define thread_local __thread
-
-		#define THREAD_LOCAL_STORAGE_SUPPORTED
-	#endif
+#define thread_local __thread
+#endif
 #endif
 
 #if __GNUC__ >= 7

src/lxc/conf.c

@@ -104,13 +104,7 @@ lxc_log_define(conf, lxc);
  * The lxc_conf of the container currently being worked on in an API call.
  * This is used in the error calls.
  */
-#if defined(THREAD_LOCAL_STORAGE_SUPPORTED)
 thread_local struct lxc_conf *current_config;
-#elif defined(ENFORCE_THREAD_SAFETY)
-#error ENFORCE_THREAD_SAFETY was set but cannot be guaranteed due to missing TLS
-#else
-struct lxc_conf *current_config;
-#endif
 
 char *lxchook_names[NUM_LXC_HOOKS] = {
 	"pre-start",

src/lxc/conf.h

@@ -474,13 +474,7 @@ struct lxc_conf {
 __hidden extern int write_id_mapping(enum idtype idtype, pid_t pid, const char *buf, size_t buf_size)
     __access_r(3, 4);
 
-#if defined(THREAD_LOCAL_STORAGE_SUPPORTED)
 extern thread_local struct lxc_conf *current_config;
-#elif defined(ENFORCE_THREAD_SAFETY)
-#error ENFORCE_THREAD_SAFETY was set but cannot be guaranteed due to missing TLS
-#else
-struct lxc_conf *current_config;
-#endif
 
 __hidden extern int run_lxc_hooks(const char *name, char *hook, struct lxc_conf *conf, char *argv[]);
 __hidden extern struct lxc_conf *lxc_conf_init(void);

src/lxc/initutils.c

@@ -54,13 +54,7 @@ const char *lxc_global_config_value(const char *option_name)
 	};
 
 	/* placed in the thread local storage pool for non-bionic targets */
-#if defined(THREAD_LOCAL_STORAGE_SUPPORTED)
 	static thread_local const char *values[sizeof(options) / sizeof(options[0])] = {0};
-#elif defined(ENFORCE_THREAD_SAFETY)
-	#error ENFORCE_THREAD_SAFETY was set but cannot be guaranteed due to missing TLS
-#else
-	static const char *values[sizeof(options) / sizeof(options[0])] = {0};
-#endif
 
 	/* user_config_path is freed as soon as it is used */
 	char *user_config_path = NULL;