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Re: [patch] improve hand-call-in-threads.exp failure handling
- From: Pedro Alves <palves at redhat dot com>
- To: Sandra Loosemore <sandra at codesourcery dot com>, gdb-patches <gdb-patches at sourceware dot org>
- Date: Tue, 08 Sep 2015 11:55:11 +0100
- Subject: Re: [patch] improve hand-call-in-threads.exp failure handling
- Authentication-results: sourceware.org; auth=none
- References: <55ECC1CC dot 6000307 at codesourcery dot com>
On 09/06/2015 11:44 PM, Sandra Loosemore wrote:
> I've been looking at some apparent regressions in nios2-linux-gnu
> gdbserver testing involving gdb.threads/hand-call-in-threads.exp. It is
> failing to stop at the breakpoint after switching to thread 2, with the
> result that all subsequent tests are timing out because we've lost the
> gdb prompt while the target is stuck running an infinite loop. Getting
> 30 more timeouts after the initial failure only slows down testing and
> doesn't provide any useful information, so we might as well just give up
> the first time.
> Then I noticed that, while all these tests used to PASS, they weren't
> really working, and never have, AFAICT. Here's an excerpt from the
> oldest archived test results I have handy (from a 2012-vintage gdb):
> (gdb) PASS: gdb.threads/hand-call-in-threads.exp: hand call, thread 1
> thread 2
> Thread ID 2 not known.
> (gdb) PASS: gdb.threads/hand-call-in-threads.exp: prepare to make hand
> call, thread 2
> call hand_call()
> Breakpoint 3, hand_call () at
> 78 }
> The program being debugged stopped while in a function called from GDB.
> Evaluation of the expression containing the function
> (hand_call) will be abandoned.
> When the function is done executing, GDB will silently stop.
> (gdb) PASS: gdb.threads/hand-call-in-threads.exp: hand call, thread 2
> Looks like the breakpoint hit test only appears to PASS because the
> "thread" command was unsuccessful and we're still in thread 1. And, the
> .exp file doesn't do anything to confirm that the "thread" command was
> successful. Nowadays the "thread" command really does switch threads
> here, but the .exp file still doesn't verify that it worked.
> This patch tightens up the handling of both failure modes. OK to commit
> as a general testsuite robustness improvement?
> This doesn't fix the broken nios2 behavior, of course. I'm still
> scratching my head.... kernel bug or something missing from the
> gdbserver target back end? :-S
Looks fine to me.