Date: Wed, 9 Nov 2005 11:34:06 -0500 From: John Baldwin <jhb@freebsd.org> To: "M. Warner Losh" <imp@bsdimp.com> 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: <200511091134.09040.jhb@freebsd.org> In-Reply-To: <20051109.092541.107741797.imp@bsdimp.com> References: <20051109204951.K68350@delplex.bde.org> <200511091001.45475.jhb@freebsd.org> <20051109.092541.107741797.imp@bsdimp.com>
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On Wednesday 09 November 2005 11:25 am, M. Warner Losh wrote: > 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... I've thought about killing taskqueue_swi in favor of taskqueue_thread actually. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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