Re: [Qemu-devel] [PATCH 3/3] qtest: kill QEMU process on g_assert() failure

["Daniel P. Berrange" <berrange@redhat.com>]

On Tue, Feb 18, 2014 at 11:07:53AM +0100, Paolo Bonzini wrote:
> Il 18/02/2014 10:05, Stefan Hajnoczi ha scritto:
> >>> SIGABRT is normally synchronous enough: it's sent by abort().  But of
> >>> course, nothing stops the user from kill -ABRT.  Or GLib from calling
> >>> abort() in some place where an attempt to reenter it crashes & burns.
> >>> Not sure I'd care, but I'm pretty sure I don't care for freeing stuff on
> >>> exit :)
> >Yes, SIGABRT is synchronous for all purposes.  So the only danger is
> >that g_string_free() or g_free() could fail while we're in
> >g_assert(false).  But they don't, which makes sense because they are
> >totally unrelated to g_assert() and therefore can handle re-entrancy.
> 
> If malloc aborts due to a double free or other similar problem, you
> may risk reentering it.

If you register the custom SIGABRT handler with sigaction + SA_RESETHAND
then you'd avoid the re-entrancy risk, since a cascading SIGABRT would
get handled by the system default handler, which would immediately
terminate the process.

Regards,
Daniel
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