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From: Christoph Hellwig <[email protected]>
To: Al Viro <[email protected]>
Cc: Christoph Hellwig <[email protected]>,
	Andrew Morton <[email protected]>,
	Jens Axboe <[email protected]>, Arnd Bergmann <[email protected]>,
	David Howells <[email protected]>,
	David Laight <[email protected]>,
	[email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected]
Subject: Re: [PATCH 5/9] fs: remove various compat readv/writev helpers
Date: Wed, 23 Sep 2020 16:32:51 +0200	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

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..

  reply	other threads:[~2020-09-23 14:32 UTC|newest]

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 [this message]
2020-09-23 14:59       ` Al Viro
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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