evl/thread: detect sleeping call with preemption disabled

Sleeping voluntarily with EVL preemption disabled is a bug. Add the
proper assertion to detect this.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

include/evl/thread.h

@@ -16,8 +16,6 @@
 #include <linux/atomic.h>
 #include <linux/spinlock.h>
 #include <linux/ptrace.h>
-#include <evl/list.h>
-#include <evl/lock.h>
 #include <evl/stat.h>
 #include <evl/init.h>
 #include <evl/timer.h>

kernel/evl/thread.c

@@ -29,7 +29,6 @@
 #include <evl/clock.h>
 #include <evl/stat.h>
 #include <evl/assert.h>
-#include <evl/lock.h>
 #include <evl/thread.h>
 #include <evl/memory.h>
 #include <evl/file.h>
@@ -490,6 +489,9 @@ void evl_sleep_on_locked(ktime_t timeout, enum evl_tmode timeout_mode,
 	struct evl_rq *rq = curr->rq;
 	unsigned long oldstate;
 
+	/* Sleeping while preemption is disabled is a bug. */
+	EVL_WARN_ON(CORE, evl_preempt_count() != 0);
+
 	assert_hard_lock(&curr->lock);
 	assert_hard_lock(&rq->lock);