Re: [PATCH] schedule() in_atomic() fix

[Robert Love <rml@tech9.net>]

On Wed, 2002-09-18 at 01:05, Andrew Morton wrote:

> Robert Love wrote:
> > 
> > +    printk(KERN_ERR "scheduling while non-atomic!\n");
> 
> When did this become illegal?  :-)

Ugh, reality is blurred... thanks.

Linus, this patch reduces the kernel by 4 bytes over the previous. 
Please, apply.

	Robert Love

diff -urN linux-2.5.36/kernel/sched.c linux/kernel/sched.c
--- linux-2.5.36/kernel/sched.c	Tue Sep 17 20:58:48 2002
+++ linux/kernel/sched.c	Wed Sep 18 00:41:09 2002
@@ -940,9 +940,6 @@
 	struct list_head *queue;
 	int idx;
 
-	if (unlikely(in_atomic()))
-		BUG();
-
 #if CONFIG_DEBUG_HIGHMEM
 	check_highmem_ptes();
 #endif
@@ -950,8 +947,20 @@
 	preempt_disable();
 	prev = current;
 	rq = this_rq();
-
 	release_kernel_lock(prev);
+
+	/*
+	 * Test if we are atomic.  Since do_exit() needs to call into
+	 * schedule() atomically, we ignore that for now.  Otherwise,
+	 * whine if we are scheduling when we should not be.
+	 */
+	if (likely(current->state != TASK_ZOMBIE)) {
+		if (unlikely((preempt_count() & ~PREEMPT_ACTIVE) != 1)) {
+			printk(KERN_ERR "scheduling while atomic!\n");
+			dump_stack();
+		}
+	}
+
 	prev->sleep_timestamp = jiffies;
 	spin_lock_irq(&rq->lock);