crash-suspend "teardown races"

[David Smith]

Roland McGrath wrote:
> Thanks, David.  That is exactly the right example of using kernel
> synchronization primitives with callbacks to implement blocking behaviors
> you want.  The wrinkle there is that you use UTRACE_INTERRUPT, which
> (potentially) perturbs the behavior of every traced thread.  Doing this
> gives you a simple a way to do synchronous detach and avoid those races.
> It's a prime example of why asynchronous detach is harder and we need to
> hash it out.  What you've done is the only thing that's straightforward to
> do now, but it has one of the bad old side effects of ptrace (interrupting
> detach) that we need to eliminate to make the facility acceptable as the
> basis for pervasive tracing of many processes on the system.

Is there a way to avoid using UTRACE_INTERRUPT?  Certainly I'd like to
avoid disturbing the processes we're tracing.

-- 
David Smith
dsmith at redhat.com
Red Hat
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