svn commit: r238907 - projects/calloutng/sys/kern

[John Baldwin]

On 9/9/12 11:03 AM, Attilio Rao wrote:
> On 8/2/12, Attilio Rao <attilio at freebsd.org> wrote:
>> On 7/30/12, John Baldwin <jhb at freebsd.org> wrote:
> 
> [ trimm ]
> 
>>> --- //depot/projects/smpng/sys/kern/subr_turnstile.c	2012-06-04
>>> 18:27:32.000000000 0000
>>> +++ //depot/user/jhb/lock/kern/subr_turnstile.c	2012-06-05
>>> 00:27:57.000000000 0000
>>> @@ -684,6 +684,7 @@
>>>  	if (owner)
>>>  		MPASS(owner->td_proc->p_magic == P_MAGIC);
>>>  	MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE);
>>> +	KASSERT(!TD_IS_IDLETHREAD(td), ("idle threads cannot block on locks"));
>>>
>>>  	/*
>>>  	 * If the lock does not already have a turnstile, use this thread's
>>
>> I'm wondering if we should also use similar checks in places doing
>> adaptive spinning (including the TD_NO_SLEEPING check). Likely yes.
> 
> So what do you think about this?

This is isn't really good enough then.  An idle thread should not
acquire any lock that isn't a spin lock.  Instead, you would be
better off removing the assert I added above and adding an assert to
mtx_lock(), rw_{rw}lock(), sx_{sx}lock(), lockmgr(), rm_{rw}lock() and
all the try variants of those.

-- 
John Baldwin