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

[Arnd Bergmann]

On Wed, Apr 29, 2020 at 3:35 PM Russell King - ARM Linux admin
 wrote:
> On Wed, Apr 29, 2020 at 03:23:24PM +0200, Arnd Bergmann wrote:
> > Two functions are not declared or defined when CONFIG_EPOLL is
> > disabled:
> >
>
> I know what Chris said, but do we really want to be polluting generic
> kernel files with arch specific stuff like this?

The file already has a couple of architecture specific syscalls listed already,
so it shouldn't be a big deal. If you prefer the first version of my patch,
or have another suggestion, I don't mind sending a v3 that does it differently
again.

Unfortunately, COND_SYSCALL() is a locally defined macro in that file,
so we can't easily use it elsewhere without duplicating it like in
kernel/time/posix-stubs.c.

As I mentioned in v1, it's also possible to just make this function
compile without #ifdefs by having conditional stub definitions of the
missing interfaces.

  Arnd

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

[Russell King - ARM Linux admin]

On Wed, Apr 29, 2020 at 03:23:24PM +0200, Arnd Bergmann wrote:
> 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, , 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 
> ---
> 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, , 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 */
>  

I know what Chris said, but do we really want to be polluting generic
kernel files with arch specific stuff like this?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 10.2Mbps down 587kbps up

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

[Arnd Bergmann]

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, , 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 
---
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, , 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