Atsushi Nemoto writes:

http://www.opengroup.org/onlinepubs/009695399/functions/posix_fadvise.html
states it returns error code instead of setting errno.

libc/sysdeps/linux/arm/posix_fadvise.c

@@ -30,8 +30,7 @@ weak_alias(__libc_posix_fadvise, posix_fadvise);
 #else
 int posix_fadvise(int fd attribute_unused, off_t offset attribute_unused, off_t len attribute_unused, int advice attribute_unused)
 {
-        __set_errno(ENOSYS);
-        return -1;
+	return ENOSYS;
 }
 #endif
 

libc/sysdeps/linux/arm/posix_fadvise64.c

@@ -40,8 +40,7 @@ weak_alias(__libc_posix_fadvise64, posix_fadvise64);
 #else
 int posix_fadvise64(int fd, __off64_t offset, __off64_t len, int advise)
 {
-        __set_errno(ENOSYS);
-        return -1;
+	return ENOSYS;
 }
 #endif
 #endif

libc/sysdeps/linux/common/posix_fadvise.c

@@ -46,7 +46,6 @@ strong_alias(posix_fadvise,posix_fadvise64)
 #else
 int posix_fadvise(int fd attribute_unused, off_t offset attribute_unused, off_t len attribute_unused, int advice attribute_unused)
 {
-	__set_errno(ENOSYS);
-	return -1;
+	return ENOSYS;
 }
 #endif

libc/sysdeps/linux/common/posix_fadvise64.c

@@ -74,8 +74,7 @@ int posix_fadvise64(int fd, __off64_t offset, __off64_t len, int advice)
  */
 int posix_fadvise64(int fd, __off64_t offset, __off64_t len, int advice)
 {
-	__set_errno(ENOSYS);
-	return -1;
+	return ENOSYS;
 }
 #endif /* __NR_fadvise64_64 */
 #endif /* __UCLIBC_HAS_LFS__ */