general question about nanosleep, usleep, semaphores and other waits.

[root <agn@city.dk>]

Hi all
This is a general question.

When using nanosleep, sem_wait, usleep etc. in RT - threds these
funktion is performed as sleep. it meens the thread is suspended until
the wakeuptime ore call to sem_post from other thred. thats fine.

But what happens withe these funktions is called from a fifo handler or
in init_module. I know that nanosleep is busy wait, but what about fx.
sem_wait funktion. My first gees is busy wait. The reason for this is
the struct
truct rtl_sem_struct
{
        int value;
        spinlock_t lock;    <- busy wait, handled differently if called
if thread
        rtl_wait_t wait;
};
and my own test.

I think that it is importent to state the mode of the funktions. it
could cause a freese.
So if anybody know the ansvar please reply

Anders Gnistrup.

ps.
I think that the question is of general interrest.