//*********************************************************
// The following is a snippet from the kernel module:
// (If the delay is put in, it works fine.)
//**********************************************************
static void *LinkThread (struct net_device *dev)
{
int status;
link_request linkr;
struct timespec ttt,xxx;
ttt.tv_sec = 2;
ttt.tv_nsec = 0;
while (1)
{
if ((status=mq_receive (link_rq_mq, (char *)&linkr, sizeof
(linkr), 0)) > 0)
{
//nanosleep (&ttt, &xxx);
status = mq_send (link_rq_mq_out, (char *)&linkr,
sizeof (linkr), 0);
}
}
return 0;
}
//******************************************************************
// Here's the user code that activates the above:
//*****************************************************************
int CLinkState::GetLinkState (void)
{
struct link_request linkr;
linkr.request_type = get_link_state;
int status;
pthread_mutex_lock (&mutex);
status = mq_send (link_rq, (char *)&linkr, sizeof (linkr), 0);
DPRINT( ("GetLinkState: mq_send returned %08x\n", status) );
mq_receive (link_rq, (char *)&linkr, sizeof (linkr), 0);
DPRINT( ("GetLinkState: mq_receive returned %08x, link up = %08x\n",
status, linkr.link_on) );
pthread_mutex_unlock (&mutex);
return linkr.link_on;
}
-----Original Message-----
From: Gilles Chanteperdrix [mailto:[EMAIL PROTECTED]
Sent: Tuesday, August 01, 2006 5:33 PM
To: Landau, Bracha
Cc: [email protected]
Subject: Re: [Xenomai-help] mq_send /mq_receive problem
Landau, Bracha wrote:
> I have a low priority thread running in the kernel which receives to a
> message queue and writes to the same message queue after it processes the
> message. The message queue is opened for reading and writing.
> Without a delay (with nanosleep) between the reading (mq_receive) and
> writing (mq_send), the kernel hangs.
> If I put in a small delay between the mq_send and mq_receive, the mechanism
> works fine.
> Why is this?
You probably found a bug, could you send us a small example allowing us
to reproduce this bug ?
--
Gilles Chanteperdrix.
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