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From: "cvs-commit at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org> To: gdb-prs@sourceware.org Subject: [Bug gdb/26199] GDB goes in busy loop when interrupting non-stop program Date: Fri, 10 Jul 2020 22:57:52 +0000 [thread overview] Message-ID: <bug-26199-4717-LWwsLhc6Fy@http.sourceware.org/bugzilla/> (raw) In-Reply-To: <bug-26199-4717@http.sourceware.org/bugzilla/> https://sourceware.org/bugzilla/show_bug.cgi?id=26199 --- Comment #5 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Pedro Alves <palves@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=d6cc5d980a902d273d424c49fc55e77757c3a05d commit d6cc5d980a902d273d424c49fc55e77757c3a05d Author: Pedro Alves <pedro@palves.net> Date: Sat Jul 4 20:51:36 2020 +0100 Make handle_no_resumed transfer terminal Let's consider the same use case as in the previous commit: Say you have two inferiors 1 and 2, each connected to a different target, A and B. Now say you set inferior 2 running, with "continue &". Now you select a thread of inferior 1, say thread 1.2, and continue in the foreground. All other threads of inferior 1 are left stopped. Thread 1.2 exits, and thus target A has no other resumed thread, so it reports TARGET_WAITKIND_NO_RESUMED. At this point, because the threads of inferior 2 are still executing the TARGET_WAITKIND_NO_RESUMED event is ignored. Now, the user types Ctrl-C. Because GDB had previously put inferior 1 in the foreground, the kernel sends the SIGINT to that inferior. However, no thread in that inferior is executing right now, so ptrace never intercepts the SIGINT -- it is never dequeued by any thread. The result is that GDB's CLI is stuck. There's no way to get back the prompt (unless inferior 2 happens to report some event). The fix in this commit is to make handle_no_resumed give the terminal to some other inferior that still has threads executing so that a subsequent Ctrl-C reaches that target first (and then GDB intercepts the SIGINT). This is a bit hacky, but seems like the best we can do with the current design. I think that putting all native inferiors in their own session would help fixing this in a clean way, since with that a Ctrl-C on GDB's terminal will _always_ reach GDB first, and then GDB can decide how to pause the inferior. But that's a much larger change. The testcase added by the following patch needs this fix. gdb/ChangeLog: PR gdb/26199 * infrun.c (handle_no_resumed): Transfer terminal to inferior with executing threads. -- You are receiving this mail because: You are on the CC list for the bug.
next prev parent reply other threads:[~2020-07-10 22:57 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-02 21:47 [Bug gdb/26199] New: " simark at simark dot ca 2020-07-02 21:48 ` [Bug gdb/26199] " simark at simark dot ca 2020-07-10 22:57 ` cvs-commit at gcc dot gnu.org 2020-07-10 22:57 ` cvs-commit at gcc dot gnu.org 2020-07-10 22:57 ` cvs-commit at gcc dot gnu.org 2020-07-10 22:57 ` cvs-commit at gcc dot gnu.org 2020-07-10 22:57 ` cvs-commit at gcc dot gnu.org [this message] 2020-07-10 22:57 ` cvs-commit at gcc dot gnu.org 2020-07-10 22:58 ` cvs-commit at gcc dot gnu.org 2020-07-10 23:05 ` palves at redhat dot com
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