lkml.org 
[lkml]   [2021]   [Aug]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[patch V5 60/72] futex: Remove bogus condition for requeue PI
    Date
    For requeue PI it's required to establish PI state for the PI futex to
    which waiters are requeued. This either acquires the user space futex on
    behalf of the top most waiter on the inner 'waitqueue' futex or attaches to
    the PI state of an existing waiter or creates on attached to the owner of
    the futex.

    This code can retry in case of failure, but retry can never happen when the
    pi state was successfully created. The condition to run this code is:

    (task_count - nr_wake) < nr_requeue

    which is always true because:

    task_count = 0
    nr_wake = 1
    nr_requeue >= 0

    Remove it all together.

    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    ---
    V4: New patch
    ---
    kernel/futex.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/kernel/futex.c
    +++ b/kernel/futex.c
    @@ -2000,7 +2000,7 @@ static int futex_requeue(u32 __user *uad
    }
    }

    - if (requeue_pi && (task_count - nr_wake < nr_requeue)) {
    + if (requeue_pi) {
    struct task_struct *exiting = NULL;

    /*
    \
     
     \ /
      Last update: 2021-08-15 23:43    [W:4.023 / U:0.280 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site