svn commit: r227394 - in head/sys: amd64/amd64 i386/i386

[Pawel Jakub Dawidek]

On Thu, Nov 10, 2011 at 12:08:39PM +0200, Kostik Belousov wrote:
> On Thu, Nov 10, 2011 at 07:23:23AM +0100, Pawel Jakub Dawidek wrote:
> > On Wed, Nov 09, 2011 at 07:31:28PM +0200, Kostik Belousov wrote:
> > > On Wed, Nov 09, 2011 at 05:25:43PM +0000, Konstantin Belousov wrote:
> > > > Author: kib
> > > > Date: Wed Nov  9 17:25:43 2011
> > > > New Revision: 227394
> > > > URL: http://svn.freebsd.org/changeset/base/227394
> > > > 
> > > > Log:
> > > >   Stopped process may legitimately have some threads sleeping and not
> > > >   suspended, if the sleep is uninterruptible.
> > > Even more, stopped process might have some threads still running in the
> > > kernel mode, or inhibited due to wait on blockable locks. I was unable
> > > to design an expression that would assert that such thread will be stopped
> > > at the kernel->user boundary.
> > > 
> > > The assertion itself is useful and catched several bugs, but theoretically
> > > can cause false positives. If any report of the fired assert for kernel-mode
> > > thread is provided, I will remove the assertions.
> > 
> > If in five years some change will make it to fire and you won't be
> > around, nobody will remember this e-mail of yours and someone will spend
> > time on looking for a bug that doesn't exist.
> > 
> > If we know it can cause false positives, I'd be in favour of removing it
> > or changing it into a warning or at the very least moving this
> > information into commit log.
> Yes, I do agree that removing the assertion is the most straightforward
> solution, but on the assertion already catched more real bugs then
> caused headaches (my headache, BTW). Either I change the third or condition
> to plain P_SHOULDSTOP(), or create a way to assert exactly what I need.

Maybe it would be easier to implement entire check in a function where
you have more flexibility and just use function's result in assertion?

-- 
Pawel Jakub Dawidek                       http://www.wheelsystems.com
FreeBSD committer                         http://www.FreeBSD.org
Am I Evil? Yes, I Am!                     http://yomoli.com
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