Re: Question about interrupt enabling/disabling in kernel exit path

From: David Mosberger-Tang <David.Mosberger_at_acm.org>
Date: 2005-11-16 08:16:27
On 11/15/05, Chen, Kenneth W <kenneth.w.chen@intel.com> wrote:
> Lee Schermerhorn wrote on Tuesday, November 15, 2005 12:21 PM
> > On Mon, 2005-11-14 at 13:52 -0800, David Mosberger-Tang wrote:
> > > > Then I notice that after we return from do_notify_resume_user() we don't
> > > > recheck TIF_NEED_RESCHED, etc. in the thread_info flags.
> > >
> > > Why do you say this?  It's not true.  After processing pending work,
> > > we go back to .work_processed_{syscall,kernel), which will again
> > > invoke .work_pending, if necessary.
> >
> > OK.  I guess I'm misinterpreting the comments on the line labeled
> > '.ret10:'.
> > Say's it's setting p6 to zero, so no recheck.  I'm not fluent [writing
> > nor reading] ia64 assembler, but it appeared to me that with p6 set to
> > zero on return from notify_resume(), the checks for more work back
> > at .work_processed_* would be disabled.
> >
>
> Looking at the code, I think Lee is correct that upon returning from
> notify_resume_user, p6 is turned off and subsequently turns off all
> the check in work_pending.

Yes, I goofed.

The ia64 code shouldn't be different from other platforms in this
respect though.  If x86 nowadays does the re-check unconditionally, we
need to look into what happened.  Perhaps x86 got updated and we
missed that update for ia64?

  --david
--
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Received on Wed Nov 16 08:17:01 2005

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