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Subject: [Xenomai-help] Strange pipe behaviour
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To: xenomai@xenomai.org

Hi,

I have the following piece of code:

RT_PIPE_MSG *msg;

while ((r = rt_pipe_receive(&mypipe, &msg, TM_INFINITE)) >= 0) {
    /* whatever */
    rt_pipe_free(msg);
}

When that thread enters, it blocks, as expected, in the rt_pipe_receive
call.

Then, from user space, I do:

echo -en "\x00" > /dev/rtp0

What happens is:

1- rt_pipe_receive returns with r >= 0.
2- /* whatever */
3- Message is freed using rt_pipe_free.
4- Next call to rt_pipe_receive returns with r = -EINTR.

The only explanation I could come up with is that when the pipe is
closed by the user mode process, the rt_pipe_receive tells the rt task
by returning -EINTR. Is this right?. According to the docs, -EINTR is
only returned if rt_task_unblock() has been called...

Nacho.