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From: Arnd Bergmann <arnd@arndb.de>
To: Matthew Wilcox <matthew@wil.cx>
Cc: Gerd Hoffmann <kraxel@redhat.com>,
	linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH v2] Add preadv and pwritev system calls.
Date: Fri, 12 Dec 2008 20:47:30 +0100	[thread overview]
Message-ID: <200812122047.31405.arnd@arndb.de> (raw)
In-Reply-To: <20081212152929.GM26095@parisc-linux.org>

On Friday 12 December 2008, Matthew Wilcox wrote:
> Things will go much better if we can prototype these as:
> 
> asmlinkage ssize_t sys_preadv(unsigned int fd, const struct iovec __user *vec,
>                                 loff_t pos, unsigned long vlen);
> asmlinkage ssize_t sys_pwritev(unsigned int fd, const struct iovec __user *vec,
>                                 loff_t pos, unsigned long vlen);

I would vote for doing it the same way as sys_llseek, which avoids
this issue entirely by passing the upper half of pos sepearately:


asmlinkage ssize_t sys_preadv(unsigned long fd,
                               const struct iovec __user *vec,
                               unsigned long vlen,
			       unsigned long pos_high, unsigned long pos_low);
asmlinkage ssize_t sys_pwritev(unsigned long fd,
                               const struct iovec __user *vec,
                               unsigned long vlen,
			       unsigned long pos_high, unsigned long pos_low);

This is the only way I can see that lets us use a shared 
compat_sys_preadv/pwritev across all 64 bit architectures.

The libc can then add a trivial wrapper around the syscalls
to get the regular calling conventions.

Aside from that, have you considered doing something even more flexible,
like this?

struct piovec {
	void __user *iov_base;
	__kernel_size_t	iov_len;
	__kernel_loff_t pos;
};

asmlinkage ssize_t sys_pwritev(unsigned long fd,
                               const struct piovec __user *vec,
                               unsigned long vlen);

	Arnd <><

  parent reply	other threads:[~2008-12-12 19:49 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-12-12 14:00 Gerd Hoffmann
2008-12-12 15:29 ` Matthew Wilcox
2008-12-12 15:48   ` Gerd Hoffmann
2008-12-12 15:51     ` Matthew Wilcox
2008-12-12 16:02       ` Gerd Hoffmann
2008-12-12 17:03         ` Matthew Wilcox
2008-12-12 18:21           ` Alan Cox
2008-12-12 19:02             ` Russell King
2008-12-12 18:29         ` Scott Lurndal
2008-12-12 19:07           ` Russell King
2008-12-12 19:56             ` Gerd Hoffmann
2008-12-12 19:56               ` Gerd Hoffmann
2008-12-12 20:12               ` Russell King
2008-12-12 20:39                 ` Gerd Hoffmann
2008-12-12 20:39                   ` Gerd Hoffmann
2008-12-14 18:19               ` Pavel Machek
2008-12-15 16:37         ` Jennifer Pioch
2008-12-15 20:43           ` Gerd Hoffmann
2008-12-16  9:57             ` Arnd Bergmann
2008-12-17  1:45               ` [osol-code] " Dan Mick
2008-12-17  1:45                 ` Dan Mick
2008-12-12 19:47   ` Arnd Bergmann [this message]
2008-12-12 20:02     ` Gerd Hoffmann
2008-12-14 11:49   ` Heiko Carstens
2008-12-15  4:14   ` Paul Mackerras
2008-12-15  6:20     ` David Miller
2008-12-12 15:40 ` Ralf Baechle
2008-12-12 16:59 ` Russell King
2008-12-13  1:18 ` Michael Kerrisk

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