Re: [PATCH/RFC] Futex mmap_sem deadlock

[Arjan van de Ven <arjan@infradead.org>]

On Wed, 2005-02-23 at 11:10 -0600, Olof Johansson wrote:
> On Wed, Feb 23, 2005 at 07:54:06AM -0800, Linus Torvalds wrote:
> 
> > > Otherwise, a preempt attempt in get_user would not be seen
> > > until some future preempt_enable was executed.
> > 
> > True. I guess we should have a "preempt_check_resched()" there too. That's 
> > what "kunmap_atomic()" does too (which is what we rely on in the other 
> > case we do this..)
> 
> Ok, this is getting complex enough to warrant get_user_inatomic(),
> which means adding it to every arch's uaccess.h.
> 
> Below patch does so. Unfortunately I don't have a Viro setup with cross
> compilers for nearly every arch, so I can't make sure it doesn't break
> anything. But since I pasted the same code everywhere it shouldn't.

I hate to do this to you, but get_user is a bit horrible in that it is
an untyped interface. Fixing it is hard (ugh) but when adding new
variants should/could we consider to please make it a typed (eg inline
and not a define) interface please ?