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From: "andrew.burgess at embecosm dot com" <sourceware-bugzilla@sourceware.org>
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Subject: [Bug gdb/27830] Attempt to resume already running thread
Date: Mon, 10 May 2021 19:24:27 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D27830

--- Comment #3 from Andrew Burgess <andrew.burgess at embecosm dot com> ---
Created attachment 13432
  --> https://sourceware.org/bugzilla/attachment.cgi?id=3D13432&action=3Ded=
it
testsuite patch

Of course, once I realised that what we have is a thread that manages to be
running when it shouldn't be, then it's easy enough to get GDB to trigger an
assertion like this:

  internal-error: int finish_step_over(execution_control_state*): Assertion
`ecs->event_thread->control.trap_expected' failed.

What's happening here is the new thread, the thread that GDB isn't expectin=
g to
be running, is hitting a stop event.  The thread then ends up inside
finish_step_over, where we make some assertions about the state of the thre=
ad
that we expect to stop.  As the thread that actually stops is not the one we
expect, things go wrong and we hit the assertion.

The attached patch adds a new testcase that exposes this issue (on
x86-64/Linux).

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