linux: Remove supports_time64 () from clock_getres

It breaks the usage case of live migration like CRIU or similar.
The performance drawback is it would require an extra syscall
on older kernels without 64-bit time support.

Checked on i686-linux-gnu on a 4.15 kernel and on a 5.11 kernel
(with and without --enable-kernel=5.1) and on x86_64-linux-gnu.

Reviewed-by: Lukasz Majewski <lukma@denx.de>

diff --git a/sysdeps/unix/sysv/linux/clock_getres.c b/sysdeps/unix/sysv/linux/clock_getres.c
index a9edec93e6d93a19cffb76689bd05a3d8c6320ca..83f05930743af1e55eba69bbfb3ddec7b2699824 100644 (file)
--- a/sysdeps/unix/sysv/linux/clock_getres.c
+++ b/sysdeps/unix/sysv/linux/clock_getres.c
@@ -21,7 +21,6 @@
 #include <time.h>
 
 #include <sysdep-vdso.h>
-#include <time64-support.h>
 #include <shlib-compat.h>
 #include <kernel-features.h>
 
@@ -34,19 +33,14 @@ __clock_getres64 (clockid_t clock_id, struct __timespec64 *res)
 #ifndef __NR_clock_getres_time64
 # define __NR_clock_getres_time64 __NR_clock_getres
 #endif
-  if (supports_time64 ())
-    {
+
 #ifdef HAVE_CLOCK_GETRES64_VSYSCALL
-      r = INLINE_VSYSCALL (clock_getres_time64, 2, clock_id, res);
+  r = INLINE_VSYSCALL (clock_getres_time64, 2, clock_id, res);
 #else
-      r = INLINE_SYSCALL_CALL (clock_getres_time64, clock_id, res);
+  r = INLINE_SYSCALL_CALL (clock_getres_time64, clock_id, res);
 #endif
-
-      if (r == 0 || errno != ENOSYS)
-       return r;
-
-      mark_time64_unsupported ();
-    }
+  if (r == 0 || errno != ENOSYS)
+    return r;
 
 #ifndef __ASSUME_TIME64_SYSCALLS
   /* Fallback code that uses 32-bit support.  */