code review 9440043: runtime: fix scanning of not started goroutines

runtime: fix scanning of not started goroutines

The stack scanner for not started goroutines ignored the arguments
area when its size was unknown.  With this change, the distance
between the stack pointer and the stack base will be used instead.

Fixes issue 5486

[cshapiro1, 2013-05-16 04:23:33]

Testing suggestions would be welcomed.

Do we have a way to leave a goroutine in the not started state?

[cshapiro1, 2013-05-16 04:24:27]

Hello golang-dev@googlegroups.com,

I'd like you to review this change to
https://code.google.com/p/go/

[bradfitz, 2013-05-16 04:27:46]

Testing: Start a bunch of goroutines in a loop and then call GC.
On May 15, 2013 9:24 PM, <cshapiro@google.com> wrote:

> Hello golang-dev@googlegroups.com,
>
> I'd like you to review this change to
> https://code.google.com/p/go/
>
>
>
https://codereview.appspot.**com/9440043/<https://codereview.appspot.com/9440...
>
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[iant, 2013-05-16 04:29:34]

Patch LGTM

I agree with bradfitz about how to get a goroutine in the not-yet-started state.

[dvyukov, 2013-05-16 06:19:31]

LGTM

[cshapiro1, 2013-05-16 17:39:17]

I have a test ready but I am not happy with its dependencies.  I suspect that
issue can be resolved in review.  As such, I am going to go ahead and submit
this change and upload the test case as a separate change.

[cshapiro1, 2013-05-16 17:42:43]

*** Submitted as https://code.google.com/p/go/source/detail?r=3623b5f14f72 ***

runtime: fix scanning of not started goroutines

The stack scanner for not started goroutines ignored the arguments
area when its size was unknown.  With this change, the distance
between the stack pointer and the stack base will be used instead.

Fixes issue 5486

R=golang-dev, bradfitz, iant, dvyukov
CC=golang-dev
https://codereview.appspot.com/9440043