Question on taskqueue_drain

[Hans Petter Selasky]

On 04/19/17 05:37, Sepherosa Ziehau wrote:
> On Wed, Apr 19, 2017 at 10:39 AM, Somayajulu, David
> <David.Somayajulu at cavium.com> wrote:
>> Sorry what I meant to ask was, whether it is O.K to call taskqueue_drain(), when an MTX_DEF lock is grabbed prior to calling taskqueue_drain().
>>
>
> You will hit WITNESS, if the drain needs to wait; that's probably the
> best case.  If the lock will be acquired in the task being drained,
> this leads to deadlock.
>

Hi,

No sleeping functions like taskqueue_drain() can be called when the 
MTX_DEF lock is grabbed.

--HPS