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From: John Baldwin <jhb@freebsd.org>
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(bigwig.baldwin.cx); Mon, 10 Sep 2012 14:43:32 -0400 (EDT)
Cc: Konstantin Belousov <kostikbel@gmail.com>,
Davide Italiano <davide@freebsd.org>, src-committers@freebsd.org,
svn-src-projects@freebsd.org
Subject: Re: svn commit: r238907 - projects/calloutng/sys/kern
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On Sunday, September 09, 2012 10:07:18 pm Attilio Rao wrote:
> On Sun, Sep 9, 2012 at 8:15 PM, John Baldwin <jhb@freebsd.org> wrote:
> > On 9/9/12 11:03 AM, Attilio Rao wrote:
> >> On 8/2/12, Attilio Rao <attilio@freebsd.org> wrote:
> >>> On 7/30/12, John Baldwin <jhb@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.
>
> What do you think about these then?
These look good, thanks!
--
John Baldwin