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Re: timed condition variable patch
Jonathan Larmour <jifl@eCosCentric.com> writes:
> Wade Jensen wrote:
> > Hello,
> > There is a very rare condition in Cyg_Condition_Variable::wait_inner(
> > Cyg_Mutex *mx, cyg_tick_count timeout ) that causes the "Unnecessary call to
> > unlock_inner()" assertion to fail.
> This looks familiar.
> Nick, I seem to recall I discussed this with you IRL in the Red Hat
> office about this, or something similar - i.e. what happens about
> timers that trigger "now" or in the past, and I think it was also in
> the context of select(). Do you remember what the outcome was? I can't
> find any kernel change resulting certainly, but then I can't remember
> the problem :-).
Yes, I also recall such a conversation, and would have sworn I made
changes to fix it. Maybe I only did this in a branch.
> > Here is a patch for this problem. It is based off of the 2.0 snapshot
> > source.
> I'd probably prefer to include the if conditional in the " if(
> self->get_wake_reason() == Cyg_Thread::NONE )" test further up. But I
> can change that later, depending on what Nick says.
Yep, this is exactly the change I intended to make. Specifically the
[I don't currently have write access to the repository, so if you
could do the honours, Jifl, I would appreciate it. And give me write
access while you are about it.]
RCS file: /cvs/ecos/ecos/packages/kernel/current/ChangeLog,v
retrieving revision 1.79
diff -u -r1.79 ChangeLog
--- ChangeLog 5 Aug 2002 21:52:58 -0000 1.79
+++ ChangeLog 7 Aug 2002 13:26:16 -0000
@@ -1,3 +1,10 @@
+2002-08-07 Nick Garnett <firstname.lastname@example.org>
+ * src/sync/mutex.cxx (Cyg_Condition_Variable::wait_inner): Only
+ wait if the timeout has not already fired. This is a result of the
+ change in semantics of unlock_reschedule() from the code that was
+ there before.
2002-08-05 Bart Veer <email@example.com>
* cdl/kernel.cdl, include/kapidata.h, include/kapi.h:
RCS file: /cvs/ecos/ecos/packages/kernel/current/src/sync/mutex.cxx,v
retrieving revision 1.14
diff -u -r1.14 mutex.cxx
--- src/sync/mutex.cxx 23 May 2002 23:06:56 -0000 1.14
+++ src/sync/mutex.cxx 7 Aug 2002 13:26:20 -0000
@@ -802,18 +802,21 @@
// Set the timer and sleep reason
self->set_timer( timeout, Cyg_Thread::TIMEOUT );
- // Only enqueue if the timeout has not already fired.
+ // Only wait if the timeout has not already fired.
if( self->get_wake_reason() == Cyg_Thread::NONE )
queue.enqueue( self );
- // Avoid calling ASRs during the following unlock.
+ // Avoid calling ASRs during the following unlock.
- // Unlock the scheduler and switch threads
+ // Unlock the scheduler and switch threads
- // Allow ASRs again
+ // Allow ASRs again
+ else Cyg_Scheduler::unlock();
CYG_ASSERTCLASS( this, "Bad this pointer");
CYG_ASSERTCLASS( mx, "Corrupt mutex");
Nick Garnett - eCos Kernel Architect