WaitQueues.

WaitQueues.

[Ralph Blach]

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Is there anyway to contionally initialize a wait queue. I want to test a
wait queue to see if has been initialized not initialize it.  If not,
how do I serialize an access to a set location so that I can atomically
test and increment that location?

Thanks

Chip

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Re: WaitQueues.

[Roland Dreier]

    Ralph> Is there anyway to contionally initialize a wait queue. I
    Ralph> want to test a wait queue to see if has been initialized
    Ralph> not initialize it.  If not, how do I serialize an access to
    Ralph> a set location so that I can atomically test and increment
    Ralph> that location?

I'm not sure about doing init_waitqueue_head() conditionally, but as
for atomic test and increment, you could use atomic_t (look at
asm/atomic.h).  That gives you atomic_inc_and_test_greater_zero()
among other things.  If you just want to set a flag,
test_and_set_bit() may be simpler.

Roland

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RE: WaitQueues.

[Ian Abbott]

On Tuesday, February 13, 2001 3:13 PM, Ralph Blach wrote:

> Is there anyway to contionally initialize a wait queue. I
> want to test a
> wait queue to see if has been initialized not initialize it.  If not,
> how do I serialize an access to a set location so that I can
> atomically
> test and increment that location?

Can't you just initialize it on driver startup or via a C initialiser
(for a statically allocated wait queue) or when you create it (for a
dynamically allocated wait queue)?

Look in <asm/atomic.h> for atomic operations.

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