From: Arnd Bergmann <arnd@arndb.de>
To: Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 3/3] generic sys_ipc wrapper
Date: Wed, 6 Jan 2010 20:52:11 +0100
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On Wednesday 06 January 2010 18:21:52 Christoph Hellwig wrote:
> 
> Add a generic implementation of the ipc demultiplexer syscall.  Except for
> s390 and sparc64 all implementations of the sys_ipc are nearly identical.

Very nice patch, too bad we didn't already do that ages ago ;)

> +		switch (version) {
> +		default: {
> +			ulong raddr;
> +			ret = do_shmat(first, (char __user *)ptr,
> +				       second, &raddr);
> +			if (ret)
> +				return ret;
> +			return put_user(raddr, (ulong __user *) third);
> +		}
> +
> +#if defined(__i386__) || defined(__frv__) || defined(__mips__) ||\
> +    defined(__mn10300__)
> +		case 1:
> +			/* iBCS2 emulator entry point */
> +			if (!segment_eq(get_fs(), get_ds()))
> +				return -EINVAL;
> +			/*
> +			 * The "(ulong *) third" is valid _only_ because of
> +			 * the kernel segment thing.
> +			 */
> +			return do_shmat(first, (char __user *) ptr, second,
> +					(unsigned long *)third);
> +#endif
> +#if defined(__arm__) || defined(__sparc__)
> +		case 1:
> +			/* Of course, we don't support iBCS2! */
> +			return -EINVAL;
> +#endif
> +		}

This would not build on any of the architecture mentioned, because of
incorrect placement of curly braces, but as Al mentioned it should just
go away entirely.

> Index: linux-2.6/arch/powerpc/include/asm/syscalls.h
> ===================================================================
> --- linux-2.6.orig/arch/powerpc/include/asm/syscalls.h	2010-01-04 15:44:58.578028035 +0100
> +++ linux-2.6/arch/powerpc/include/asm/syscalls.h	2010-01-04 15:45:57.408253467 +0100
> @@ -35,8 +35,6 @@ asmlinkage long sys_pipe2(int __user *fi
>  asmlinkage long sys_rt_sigaction(int sig,
>  		const struct sigaction __user *act,
>  		struct sigaction __user *oact, size_t sigsetsize);
> -asmlinkage int sys_ipc(uint call, int first, unsigned long second,
> -		long third, void __user *ptr, long fifth);
>  asmlinkage long ppc64_personality(unsigned long personality);
>  asmlinkage int ppc_rtas(struct rtas_args __user *uargs);
>  asmlinkage time_t sys64_time(time_t __user * tloc);

I did not see you add the prototype back into include/linux/syscalls.h,
which is required for building some architectures, including ppc64 with
SPU support.

	Arnd
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