cvs commit: src/sys/kern subr_power.c

[M. Warner Losh]

In message: <200511091001.45475.jhb at freebsd.org>
            John Baldwin <jhb at 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...