lkml.org 
[lkml]   [2010]   [Mar]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [RFC 09/15] PM / Hibernate: user, implement user_ops writer
    Date
    On Wednesday 24 March 2010, Jiri Slaby wrote:
    > On 03/24/2010 09:42 PM, Pavel Machek wrote:
    > >> + if (test_bit(TODO_CLOSED, to_do_flags))
    > >> + return -EIO;
    > >> +
    > >> + to_do_buf = buf;
    > >> + wmb();
    > >> + set_bit(TODO_WORK, to_do_flags);
    > >> + wake_up_interruptible(&to_do_wait);
    > >
    > > Uhuh, open-coded barriers... these need to be commented, and I guess
    > > you just should not play this kind of trickery.
    >
    > It's just to ensure the to_do_buf store is not reordered with the
    > set_bit. I wanted to avoid locks as too heavy tools here.

    No, please use them, at least in a prototype version.

    We can always optimize things out later, but doing optimizations upfront
    doesn't really work well from my experience.

    So, if you'd use a lock somewhere, please use it, or maybe use a completion if
    that fits the design better. In the majority of cases it's not as heavy wieght
    as it seems at first sight.

    Rafael


    \
     
     \ /
      Last update: 2010-03-25 23:15    [W:0.020 / U:0.292 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site