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From: Al Viro <viro@zeniv.linux.org.uk>
To: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Jens Axboe <axboe@kernel.dk>, Arnd Bergmann <arnd@arndb.de>,
	David Howells <dhowells@redhat.com>,
	David Laight <David.Laight@aculab.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
	linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-s390@vger.kernel.org, sparclinux@vger.kernel.org,
	linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-aio@kvack.org,
	io-uring@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-mm@kvack.org, netdev@vger.kernel.org,
	keyrings@vger.kernel.org, linux-security-module@vger.kernel.org
Subject: Re: [PATCH 5/9] fs: remove various compat readv/writev helpers
Date: Wed, 23 Sep 2020 15:59:01 +0100
Message-ID: <20200923145901.GN3421308@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20200923143251.GA14062@lst.de>

On Wed, Sep 23, 2020 at 04:32:51PM +0200, Christoph Hellwig wrote:
> On Wed, Sep 23, 2020 at 03:25:49PM +0100, Al Viro wrote:
> > On Wed, Sep 23, 2020 at 08:05:43AM +0200, Christoph Hellwig wrote:
> > >  COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd,
> > > -		const struct compat_iovec __user *,vec,
> > > +		const struct iovec __user *, vec,
> > 
> > Um...  Will it even compile?
> > 
> > >  #ifdef __ARCH_WANT_COMPAT_SYS_PREADV64
> > >  COMPAT_SYSCALL_DEFINE4(preadv64, unsigned long, fd,
> > > -		const struct compat_iovec __user *,vec,
> > > +		const struct iovec __user *, vec,
> > 
> > Ditto.  Look into include/linux/compat.h and you'll see
> > 
> > asmlinkage long compat_sys_preadv64(unsigned long fd,
> >                 const struct compat_iovec __user *vec,
> >                 unsigned long vlen, loff_t pos);
> > 
> > How does that manage to avoid the compiler screaming bloody
> > murder?
> 
> That's a very good question.  But it does not just compile but actually
> works.  Probably because all the syscall wrappers mean that we don't
> actually generate the normal names.  I just tried this:
> 
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -468,7 +468,7 @@ asmlinkage long sys_lseek(unsigned int fd, off_t offset,
>  asmlinkage long sys_read(unsigned int fd, char __user *buf, size_t count);
>  asmlinkage long sys_write(unsigned int fd, const char __user *buf,
>                             size_t count);
> -asmlinkage long sys_readv(unsigned long fd,
> +asmlinkage long sys_readv(void *fd,
> 
> for fun, and the compiler doesn't care either..

Try to build it for sparc or ppc...

  reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-23  6:05 let import_iovec deal with compat_iovecs as well v3 Christoph Hellwig
2020-09-23  6:05 ` [PATCH 1/9] compat.h: fix a spelling error in <linux/compat.h> Christoph Hellwig
2020-09-23  6:05 ` [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c Christoph Hellwig
2020-09-23  6:05 ` [PATCH 3/9] iov_iter: refactor rw_copy_check_uvector and import_iovec Christoph Hellwig
2020-09-23 14:16   ` Al Viro
2020-09-23 14:38     ` David Laight
2020-09-23 14:49       ` Al Viro
2020-09-23 14:40     ` Al Viro
2020-09-23  6:05 ` [PATCH 4/9] iov_iter: transparently handle compat iovecs in import_iovec Christoph Hellwig
2020-09-23  6:05 ` [PATCH 5/9] fs: remove various compat readv/writev helpers Christoph Hellwig
2020-09-23 14:25   ` Al Viro
2020-09-23 14:32     ` Christoph Hellwig
2020-09-23 14:59       ` Al Viro [this message]
2020-09-23 16:38         ` Al Viro
2020-09-23 17:05           ` Al Viro
2020-09-23 17:46             ` Christoph Hellwig
2020-09-23 17:08           ` Brian Gerst
2020-09-23 18:45           ` Arnd Bergmann
2020-09-23 19:47             ` Al Viro
2020-09-23 19:52               ` Arnd Bergmann
2020-09-23 21:30             ` David Laight
2020-09-23  6:05 ` [PATCH 6/9] fs: remove the compat readv/writev syscalls Christoph Hellwig
2020-09-23  6:05 ` [PATCH 7/9] fs: remove compat_sys_vmsplice Christoph Hellwig
2020-09-23  6:05 ` [PATCH 8/9] mm: remove compat_process_vm_{readv,writev} Christoph Hellwig
2020-09-23  6:05 ` [PATCH 9/9] security/keys: remove compat_keyctl_instantiate_key_iov Christoph Hellwig
  -- strict thread matches above, loose matches on Subject: below --
2020-09-25  4:51 let import_iovec deal with compat_iovecs as well v4 Christoph Hellwig
2020-09-25  4:51 ` [PATCH 5/9] fs: remove various compat readv/writev helpers Christoph Hellwig
2020-09-18 12:45 let import_iovec deal with compat_iovecs as well Christoph Hellwig
2020-09-18 12:45 ` [PATCH 5/9] fs: remove various compat readv/writev helpers Christoph Hellwig

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