lkml.org 
[lkml]   [2005]   [Feb]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH/RFC] Futex mmap_sem deadlock
    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.

    My turn to say uglee.

    Firstly, get_user_inatomic is the wrong name.

    "inatomic" in __copy_from_user_inatomic means it's called inside a
    non-premptable region (in atomic...).

    Your macro get_user_inatomic is _not_ called inside a
    non-preemptable region, so it shouldn't be called "inatomic".

    (A better name is get_user_no_paging).

    Secondly, does this _one_ use (it's not likely to be used elsewhere)
    justify copying & pasting the same code into every asm-*/uaccess,
    especially when the code is not in any way arch-specific?

    I suggest putting it into futex.c, and make it an inline function
    which takes "u32 __user *".

    -- Jamie
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 14:10    [W:5.658 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site