lkml.org 
[lkml]   [2002]   [Dec]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[patch 2.5.51] add wait_event() to <linux/completion.h>
    Folk periodically talk about evolving the "struct completion"
    support ... here's one:

    int wait_event (struct completion *x, signed long timeout_jiffies);

    Returns zero if the event happened, nonzero if it timed out.
    An example timeout action might be to cancel a request then
    use wait_for_completion(x) to synchronize with that.

    It's been behaving for me so far. Questions from me:

    - Is this appropriate to merge as-is? The tradeoff I'm
    thinking of is code duplication; this patch avoids it
    ("smaller==better" rule-of-thumb) but maybe someone has
    real tuning knowledge, or a "standard" lk policy applies.
    Or there might be bugs or api transgressions.

    - One routine was unavailable to modules; now exported.
    That seemed to just be an oversight.

    This doesn't add an "interruptible wait" api mode, which
    I'd expect some others might find a use for. This patch
    will let us clean up some dubious code in usbcore which
    is more or less trying to do a wait_event().

    Thanks in advance for any comments.

    - Dave
    --- ./include/linux-dist/completion.h Sun Dec 8 10:57:47 2002
    +++ ./include/linux/completion.h Mon Dec 9 15:11:51 2002
    @@ -28,6 +28,7 @@
    }

    extern void FASTCALL(wait_for_completion(struct completion *));
    +extern int FASTCALL(wait_timeout(struct completion *, signed long jiffies));
    extern void FASTCALL(complete(struct completion *));
    extern void FASTCALL(complete_all(struct completion *));

    --- ./kernel-dist/ksyms.c Sun Dec 8 10:57:48 2002
    +++ ./kernel/ksyms.c Mon Dec 9 15:13:47 2002
    @@ -404,7 +404,9 @@ EXPORT_SYMBOL(autoremove_wake_function);

    /* completion handling */
    EXPORT_SYMBOL(wait_for_completion);
    +EXPORT_SYMBOL(wait_timeout);
    EXPORT_SYMBOL(complete);
    +EXPORT_SYMBOL(complete_all);

    /* The notion of irq probe/assignment is foreign to S/390 */

    --- ./kernel-dist/sched.c Sun Dec 8 10:57:48 2002
    +++ ./kernel/sched.c Mon Dec 9 15:34:36 2002
    @@ -1204,6 +1204,11 @@ void complete_all(struct completion *x)

    void wait_for_completion(struct completion *x)
    {
    + wait_timeout (x, MAX_SCHEDULE_TIMEOUT);
    +}
    +
    +int wait_timeout(struct completion *x, signed long timeout_jiffies)
    +{
    might_sleep();
    spin_lock_irq(&x->wait.lock);
    if (!x->done) {
    @@ -1214,13 +1219,19 @@ void wait_for_completion(struct completi
    do {
    __set_current_state(TASK_UNINTERRUPTIBLE);
    spin_unlock_irq(&x->wait.lock);
    - schedule();
    + timeout_jiffies = schedule_timeout(timeout_jiffies);
    + if (timeout_jiffies == 0) {
    + __remove_wait_queue(&x->wait, &wait);
    + /* caller should wait again */
    + return 1;
    + }
    spin_lock_irq(&x->wait.lock);
    } while (!x->done);
    __remove_wait_queue(&x->wait, &wait);
    }
    x->done--;
    spin_unlock_irq(&x->wait.lock);
    + return 0;
    }

    #define SLEEP_ON_VAR \
    \
     
     \ /
      Last update: 2005-03-22 13:31    [W:0.037 / U:4.652 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site