[PATCH] [v2] ARM: oabi-compat: fix epoll_ctl build failure

[Arnd Bergmann <arnd@xxxxxxxx>]

Two functions are not declared or defined when CONFIG_EPOLL is
disabled:

arch/arm/kernel/sys_oabi-compat.c: In function 'sys_oabi_epoll_ctl':
arch/arm/kernel/sys_oabi-compat.c:258:6: error: implicit declaration of function 'ep_op_has_event' [-Werror=implicit-function-declaration]
  258 |  if (ep_op_has_event(op) &&
      |      ^~~~~~~~~~~~~~~
arch/arm/kernel/sys_oabi-compat.c:265:9: error: implicit declaration of function 'do_epoll_ctl'; did you mean 'sys_epoll_ctl'? [-Werror=implicit-function-declaration]
  265 |  return do_epoll_ctl(epfd, op, fd, &kernel, false);
      |         ^~~~~~~~~~~~
      |         sys_epoll_ctl

Replace the function with the sys_ni_syscall stub in this case.

Fixes: c281634c8652 ("ARM: compat: remove KERNEL_DS usage in sys_oabi_epoll_ctl()")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
v2: use sys_ni_syscall() instead of removing the function body
---
 arch/arm/kernel/sys_oabi-compat.c | 2 ++
 kernel/sys_ni.c                   | 1 +
 2 files changed, 3 insertions(+)

diff --git a/arch/arm/kernel/sys_oabi-compat.c b/arch/arm/kernel/sys_oabi-compat.c
index 85a1e95341d8..2488c69242cf 100644
--- a/arch/arm/kernel/sys_oabi-compat.c
+++ b/arch/arm/kernel/sys_oabi-compat.c
@@ -249,6 +249,7 @@ struct oabi_epoll_event {
 	__u64 data;
 } __attribute__ ((packed,aligned(4)));
 
+#ifdef CONFIG_EPOLL
 asmlinkage long sys_oabi_epoll_ctl(int epfd, int op, int fd,
 				   struct oabi_epoll_event __user *event)
 {
@@ -264,6 +265,7 @@ asmlinkage long sys_oabi_epoll_ctl(int epfd, int op, int fd,
 
 	return do_epoll_ctl(epfd, op, fd, &kernel, false);
 }
+#endif
 
 asmlinkage long sys_oabi_epoll_wait(int epfd,
 				    struct oabi_epoll_event __user *events,
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 42ce28c460f6..9ee6a46b1795 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -68,6 +68,7 @@ COND_SYSCALL(epoll_create1);
 COND_SYSCALL(epoll_ctl);
 COND_SYSCALL(epoll_pwait);
 COND_SYSCALL_COMPAT(epoll_pwait);
+COND_SYSCALL(oabi_epoll_ctl); /* ARM OABI specific */
 
 /* fs/fcntl.c */
 
-- 
2.26.0