lkml.org 
[lkml]   [2014]   [Feb]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [RFC][PATCH 5/5] arch: Sanitize atomic_t bitwise ops
    From
    On Thu, Feb 6, 2014 at 9:52 AM, Peter Zijlstra <peterz@infradead.org> wrote:
    >
    > s390 is stuffed with atomic_{set,clear}_mask usage, no clue whatfor.

    It's not the set/clear_mask ones I would worry about.

    It's the "_return" variants. As far as I can tell, there are exactly
    ZERO users of that stuff, and they are BAD BAD BAD.

    On x86, those things would cause a cmpxchg loop, and the bad
    read-for-shared-before-acquire cacheline pattern.

    So why indirectly encourage people to add users for a bad operation?

    Linus


    \
     
     \ /
      Last update: 2014-02-06 19:41    [W:8.192 / U:0.012 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site