Re: [git pull] uaccess-related bits of vfs.git

Al Viro
2017-05-13T19:57:03Z

On Sat, May 13, 2017 at 12:00:10PM -0700, Linus Torvalds wrote:
> > We should probably even consider looking at __get_user/__put_user().
> > Few of them are actually performance-critical.
>
> Look at that date. It's over two years ago. In the intervening two
> years, how many of those conversions have happened?
>
> Here's a hint: it's a very very round number.

FWIW, just this cycle (this one I remembered off-hand, there might be
more):

commit edb88cef0570914375d461107759cf0d6d677ed5
Author: Arnd Bergmann <arnd@arndb.de>
Date: Sat Apr 22 00:02:31 2017 +0200

scsi: pmcraid: use normal copy_from_user

As pointed out by Al Viro for my previous series, the driver has no need
to call access_ok() and __copy_from_user()/__copy_to_user(). Changing
it to regular copy_from_user()/copy_to_user() simplifies the code without
any real downsides, making it less error-prone at best.

This patch by itself also addresses the warning about the access_ok()
macro on MIPS, but both fixes improve the code, so ideally we apply
them both.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>