From mboxrd@z Thu Jan  1 00:00:00 1970
From: milton@krutt.org (Milton Krutt)
Date: Mon, 23 Mar 2015 05:31:51 -0700
Subject: apparent sleep
Message-ID: <20150323123151.GB4484@debian>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

Hi.

Following LDD3, I am dealing with wait queues, on a 2.6.10.

My loop is like:

while(enough()){

prepare_to_wait(&queue_head, &queue_entry, TASK_INTERRUPTIBLE);

atomic_set(&flag, 0);

if (!atomic_read(&flag, 0))
	schedule();

finish_wait(&queue_head, &queue_entry);

		}

My intention is to wake up the process at each loop by issuing CTRL^D.

Here is what happens:

the first time the process yields the processor, it actually sleeps and
I have to give it a CTRL^D in order to put it again in running state;
unfortunately, in the following loops, although it calls the schedule()
function, it magically regains the processor putting hisself in a running
state (since it runs, I guess the state is a running one).

In a few words, the while loop has thousands of iterations, but CTRL^D is
needed only during the first one.


Thank you all