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RE: [PATCH] btrace: avoid tp != NULL assertion
- From: "Metzger, Markus T" <markus dot t dot metzger at intel dot com>
- To: Pedro Alves <palves at redhat dot com>
- Cc: "gdb-patches at sourceware dot org" <gdb-patches at sourceware dot org>
- Date: Tue, 3 Mar 2015 15:37:41 +0000
- Subject: RE: [PATCH] btrace: avoid tp != NULL assertion
- Authentication-results: sourceware.org; auth=none
- References: <1423473902-2286-1-git-send-email-markus dot t dot metzger at intel dot com> <54F4DF9D dot 3060400 at redhat dot com> <A78C989F6D9628469189715575E55B231E6EEF71 at IRSMSX104 dot ger dot corp dot intel dot com> <54F5A12F dot 9000702 at redhat dot com> <A78C989F6D9628469189715575E55B231E6EF176 at IRSMSX104 dot ger dot corp dot intel dot com> <54F5BA0B dot 2000106 at redhat dot com> <A78C989F6D9628469189715575E55B231E6EF452 at IRSMSX104 dot ger dot corp dot intel dot com> <54F5BF28 dot 5030108 at redhat dot com> <A78C989F6D9628469189715575E55B231E6EF4BB at IRSMSX104 dot ger dot corp dot intel dot com> <54F5D263 dot 4080008 at redhat dot com>
> -----Original Message-----
> From: Pedro Alves [mailto:firstname.lastname@example.org]
> Sent: Tuesday, March 3, 2015 4:25 PM
> To: Metzger, Markus T
> Cc: email@example.com
> Subject: Re: [PATCH] btrace: avoid tp != NULL assertion
> >>>>> No, that wasn't the reason for replacing the assert. There are no such
> >>>>> errors in the gdb.btrace suite (which is mostly single-threaded) with
> >>>>> patch and I have not seen any such errors otherwise, either.
> >>>> Then it sounds like we're either lacking basic tests, or the threaded
> >>>> are somehow not running correctly when gdb is a 32-bit program. I
> >>>> that if you step any non-leader thread, you should see it happen.
> >>>> Grepping the tests, I think gdb.btrace/multi-thread-step.exp should
> >>>> caught it. My machine doesn't do btrace, so I can't try it myself...
> >>>> BTW, did any existing test in the testsuite catch the assertion we're
> >>>> fixing?
> >>> Almost all of them when run on 32-bit systems; -m32 on 64-bit systems
> >> does
> >>> not catch this.
> >> Right, that's why I said "when gdb is a 32-bit program". Sounds like
> >> no existing test tries a "step" when not replaying then. It'd be very
> >> nice to have one. Can I convince you to add one? :-)
> > The multi-thread-step.exp test does not catch it because it uses "cont",
> > which works fine. When I add a "step" before the "cont", I get the
> > "No thread" error when using my old patch instead of your new patch.
> > Or I get the assert when using neither my old nor your new patch.
> > But then, I got the assert already on other tests.
> > With my patch dropped and your patch committed, what is the new
> > test expected to catch?
> You're getting me confused...
> The test was expected to catch the assertion, given that apparently
> no other test was catching it -- from the dialog above, one understands
> no test would be catching this before (that's what I explicitly
> asked), but now you're saying the opposite.
I think that was a misunderstanding. The assertion is caught by several
gdb.btrace tests when run with 32-bit GDB.
I thought you were referring to the badness in my patch that would
result in GDB asking for registers in a wrong process.
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