Hi,
I am trying to udnerstand the code of semaphores..
following the function down_trylock .. i got to __down_trylock..
spin_lock_irqsave(&semaphore_lock, flags);
sleepers = sem->sleepers + 1;
sem->sleepers = 0;
/*
* Add "everybody else" and us into it. They aren't
* playing, because we own the spinlock.
*/
if (!atomic_add_negative(sleepers, &sem->count))
----->>> wake_up(&sem->wait); <<<----
spin_unlock_irqrestore(&semaphore_lock, flags);
return 1;
Why is it waking up the sleeping process here? Isnt down_trylock supposed
to 'try to' acquire the sem, and if cant then to simply return imm.
And shouldnt wake_up be called only when 'releasing' a semaphore via the
up() function call?
-Learner
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