linux-kernel - Re: [PATCH] [v2] ARM: oabi-compat: fix epoll

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Date:   Wed, 29 Apr 2020 14:35:12 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Christoph Hellwig <hch@....de>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-api@...r.kernel.org
Subject: Re: [PATCH] [v2] ARM: oabi-compat: fix epoll_ctl build failure

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, &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@...db.de>
> ---
> 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 */
>  

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/
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