Date: Wed, 09 Nov 2005 09:25:41 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: jhb@FreeBSD.org Cc: cvs-src@FreeBSD.org, scottl@samsco.org, src-committers@FreeBSD.org, cvs-all@FreeBSD.org, bde@zeta.org.au Subject: Re: cvs commit: src/sys/kern subr_power.c Message-ID: <20051109.092541.107741797.imp@bsdimp.com> In-Reply-To: <200511091001.45475.jhb@freebsd.org> References: <20051109204951.K68350@delplex.bde.org> <4371FFF1.7020902@samsco.org> <200511091001.45475.jhb@freebsd.org>
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In message: <200511091001.45475.jhb@freebsd.org>
John Baldwin <jhb@freebsd.org> writes:
: On Wednesday 09 November 2005 08:56 am, Scott Long wrote:
: > Bruce Evans wrote:
: > > On Wed, 9 Nov 2005, Warner Losh wrote:
: > >> Modified files:
: > >> sys/kern subr_power.c
: > >> Log:
: > >> Kick off the suspend sequence from the keyboard in a SWI rather than
: > >> in the hardware interrupt context (even if it is likely just an
: > >> ithread). We don't document that suspend/resume routines are run from
: > >> such a context and some of the things that happen in those routines
: > >> aren't interrupt safe. Since there's no real need to run from that
: > >> context, this restores assumptions that suspend routines have made.
: > >>
: > >> This fixes Thierry Herbelot's 'Trying to sleep while sleeping is
: > >> prohibited' problem.
: > >
: > > Er, SWIs are interrupts too. Trying to sleep in a SWI handler should
: > > cause the same message. This commit uses the general taskqueue SWI
: > > handler. taskqueue(9) implicitly says that only the taskqueue thread
: > > handler can sleep (it gives malloc(M_WAITOK) as an example of something
: > > that can only be done in thread context).
: > >
: > > Bruce
: >
: > You're right, but sleeping in SWI's has never been enforced. CAM relies
: > on it, for better or worse, and until that's fixed it's pointless to
: > start enforcing it.
:
: Well, I don't think we should knowingly go around adding more instances of
: it. :) In this case it is really easy to just use taskqueue_thread rather
: than taskqueue_swi.
SWI, thread, what's the difference? [*] In this case, nothing bad will
happen if we do this in a thread and bad things might happen in the
future if we don't. Sounds like a no-brainer: I changed it to
taskqueue_thread.
Warner
[*] That's actually a good question to have answered in the taskqueue
man page... I use it as a rhetorical question here...
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