compat: let architectures define __ARCH_WANT_COMPAT_SYS_GETDENTS64

For architecture dependent compat syscalls in common code an architecture
must define something like __ARCH_WANT_<WHATEVER> if it wants to use the
code.
This however is not true for compat_sys_getdents64 for which architectures
must define __ARCH_OMIT_COMPAT_SYS_GETDENTS64 if they do not want the code.

This leads to the situation where all architectures, except mips, get the
compat code but only x86_64, arm64 and the generic syscall architectures
actually use it.

So invert the logic, so that architectures actively must do something to
get the compat code.

This way a couple of architectures get rid of otherwise dead code.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/compat.h b/include/linux/compat.h
index 3f448c6..beded18 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -502,9 +502,11 @@ asmlinkage long compat_sys_old_readdir(unsigned int fd,
 asmlinkage long compat_sys_getdents(unsigned int fd,
 				    struct compat_linux_dirent __user *dirent,
 				    unsigned int count);
+#ifdef __ARCH_WANT_COMPAT_SYS_GETDENTS64
 asmlinkage long compat_sys_getdents64(unsigned int fd,
 				      struct linux_dirent64 __user *dirent,
 				      unsigned int count);
+#endif
 asmlinkage long compat_sys_vmsplice(int fd, const struct compat_iovec __user *,
 				    unsigned int nr_segs, unsigned int flags);
 asmlinkage long compat_sys_open(const char __user *filename, int flags,