Jeroen Van den Keybus wrote:
> Gilles, Jan,
>
>
> The offending program is quite complex (several .c files and
> a considerable .h file tree) and involves 2 computers. However, I think I
> can narrow down the problem to concurrent access (from 2 Xenomai threads in
> 2nd domain) to the same Linux file descriptor for a TCP/IP connection.
>
> In order to rule this out, I have put RT_MUTEXes around the send() and
> recv() calls.However, I still received 'scheduling while atomic'. Further
> investigation, however, has shown that the mutexes seem to fail:
> rt_mutex_enquire() returns 0 or even -1 after acquisition of the lock. With
> this program, I didn't (yet) receive the 'scheduling...' error, but by
> increasing the task repetition rate, it should be a matter of (a long) time
> (both tasks arriving at a blocking write).
>
> I have compiled a program that represents the structure of the original
> program. Could you have a look and see if I'm not making a mistake here ?
>
> For proper following up, I've also attached the dmesg log asked for earlier
> by Jan.
Looking at the message log, it seems xnshadow_harden is called at a
point where irqs are disabled. But is there no other error before these
"scheduling while atomic" messages ? If not, could you try and enable
the nucleus debugging ?
In case there is no error before the error messages, even with nucleus
debugging activated, I attached a patch which breaks nklock and
activates interrupts on xnshadow_harden entry and restore the caller
state on xnshadow_harden exit. Could you test it and report if you still
see the "scheduling while atomic" messages ?
--
Gilles Chanteperdrix.
Index: ksrc/nucleus/shadow.c
===================================================================
--- ksrc/nucleus/shadow.c (revision 464)
+++ ksrc/nucleus/shadow.c (working copy)
@@ -439,13 +439,17 @@
preemption. */
struct __gatekeeper *gk = &gatekeeper[task_cpu(this_task)];
xnthread_t *thread = xnshadow_thread(this_task);
+ spl_t s;
if (!thread)
return -EPERM;
+ xnlock_get_irqsave(&nklock, s);
+ xnlock_clear_irqon(&nklock);
+
if (signal_pending(this_task) ||
down_interruptible(&gk->sync)) /* Grab the request token. */
- return -ERESTARTSYS;
+ goto out_interrupted;
xnltt_log_event(xeno_ev_primarysw,this_task->comm);
@@ -495,6 +499,8 @@
thread->name,
xnthread_user_pid(thread));
#endif /* CONFIG_XENO_OPT_DEBUG */
+out_interrupted:
+ xnlock_put_irqrestore(&nklock, s);
return -ERESTARTSYS;
}
}
@@ -510,7 +516,7 @@
if (xnthread_signaled_p(thread))
xnpod_dispatch_signals();
- xnlock_clear_irqon(&nklock);
+ xnlock_put_irqrestore(&nklock, s);
xnltt_log_event(xeno_ev_primary,thread->name);
