RE: Question on Schedule and Preemption

[Michael Guo]

Hi,
 The comments above the piece of code give some hints about the sane checking. When call "schedule" for process scheduling, make sure that context isn't atomic. That is, schedule should be called in a safe place such as spinlock free etc. And you can also read do_exit() code to get more detailed information.


   

-----Original Message-----
From: linux-kernel-owner@xxxxxxxxxxxxxxx
[mailto:linux-kernel-owner@xxxxxxxxxxxxxxx]On Behalf Of Liu haixiang
Sent: Tuesday, April 18, 2006 3:23 AM
To: linux-kernel@xxxxxxxxxxxxxxx
Subject: Question on Schedule and Preemption


Hi All,

Now I am developing the driver on Linux kernel 2.6.11. And I met the
problem that kernel will dump my stack from time to time. And the
kernel log will give me messages like "scheduling while atomic: ...".

Then I found the code in sched.c:

if (likely(!current->exit_state)) {
	if (unlikely(in_atomic())) {
		printk(KERN_ERR "scheduling while atomic: "
			"%s/0x%08x/%d\n",
			current->comm, preempt_count(), current->pid);
		dump_stack();
	}
}

Anybody can explain above code for me?

Thanks

best regards

Haixiang Liu
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