From patchwork Mon Nov 4 10:23:35 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Simon Marchi (Code Review)" X-Patchwork-Id: 35610 Received: (qmail 90354 invoked by alias); 4 Nov 2019 10:23:48 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 90302 invoked by uid 89); 4 Nov 2019 10:23:47 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-21.3 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3 autolearn=ham version=3.3.1 spammy=23703 X-HELO: mx1.osci.io Received: from polly.osci.io (HELO mx1.osci.io) (8.43.85.229) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 04 Nov 2019 10:23:45 +0000 Received: by mx1.osci.io (Postfix, from userid 994) id 81A3D20266; Mon, 4 Nov 2019 05:23:43 -0500 (EST) Received: from gnutoolchain-gerrit.osci.io (gnutoolchain-gerrit.osci.io [8.43.85.239]) by mx1.osci.io (Postfix) with ESMTP id 54ABD2047F; Mon, 4 Nov 2019 05:23:36 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by gnutoolchain-gerrit.osci.io (Postfix) with ESMTP id 331FD25B28; Mon, 4 Nov 2019 05:23:36 -0500 (EST) X-Gerrit-PatchSet: 2 Date: Mon, 4 Nov 2019 05:23:35 -0500 From: "Tankut Baris Aktemur (Code Review)" To: Luis Machado , gdb-patches@sourceware.org Auto-Submitted: auto-generated X-Gerrit-MessageType: newpatchset Subject: [review v2] infrun: handle already-exited threads when attempting to stop X-Gerrit-Change-Id: I7cec98f40283773b79255d998511da434e9cd408 X-Gerrit-Change-Number: 133 X-Gerrit-ChangeURL: X-Gerrit-Commit: a32b3dcee11cd3a9f40c5f07757a514074b9051f In-Reply-To: References: Reply-To: tankut.baris.aktemur@intel.com, luis.machado@linaro.org, gdb-patches@sourceware.org MIME-Version: 1.0 Content-Disposition: inline User-Agent: Gerrit/3.0.3-75-g9005159e5d Message-Id: <20191104102336.331FD25B28@gnutoolchain-gerrit.osci.io> Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/133 ...................................................................... infrun: handle already-exited threads when attempting to stop In stop_all_threads, GDB sends signals to other threads in an attempt to stop them. While in a typical scenario the expected wait status is TARGET_WAITKIND_STOPPED, it is possible that the thread GDB attempted to stop has already terminated. If so, a waitstatus other than TARGET_WAITKIND_STOPPED would be received. Handle this case appropriately. If a wait status that denotes thread termination is ignored, GDB goes into an infinite loop in stop_all_threads. E.g.: ~~~ $ gdb ./a.out (gdb) start ... (gdb) add-inferior -exec ./a.out ... (gdb) inferior 2 ... (gdb) start ... (gdb) set schedule-multiple on (gdb) set debug infrun 2 (gdb) continue Continuing. infrun: clear_proceed_status_thread (process 23419) infrun: clear_proceed_status_thread (process 23703) infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT) infrun: proceed: resuming process 23419 infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 23419] at 0x55555555514e infrun: infrun_async(1) infrun: prepare_to_wait infrun: proceed: resuming process 23703 infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 23703] at 0x55555555514e infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: 23703.23703.0 [process 23703], infrun: status->kind = exited, status = 0 infrun: handle_inferior_event status->kind = exited, status = 0 [Inferior 2 (process 23703) exited normally] infrun: stop_waiting infrun: stop_all_threads infrun: stop_all_threads, pass=0, iterations=0 infrun: process 23419 executing, need stop infrun: target_wait (-1.0.0, status) = infrun: 23419.23419.0 [process 23419], infrun: status->kind = exited, status = 0 infrun: stop_all_threads status->kind = exited, status = 0 process 23419 infrun: process 23419 executing, already stopping infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [process -1], infrun: status->kind = no-resumed infrun: stop_all_threads status->kind = no-resumed process -1 infrun: process 23419 executing, already stopping infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [process -1], infrun: status->kind = no-resumed infrun: stop_all_threads status->kind = no-resumed process -1 infrun: process 23419 executing, already stopping infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [process -1], infrun: status->kind = no-resumed infrun: stop_all_threads status->kind = no-resumed process -1 infrun: process 23419 executing, already stopping infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [process -1], infrun: status->kind = no-resumed infrun: stop_all_threads status->kind = no-resumed process -1 infrun: process 23419 executing, already stopping ~~~ And this polling goes on forever. This patch prevents the infinite looping behavior. For the same scenario above, we obtain the following behavior: ~~~ ... (gdb) continue Continuing. infrun: clear_proceed_status_thread (process 1635) infrun: clear_proceed_status_thread (process 1763) infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT) infrun: proceed: resuming process 1635 infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 1635] at 0x55555555514e infrun: infrun_async(1) infrun: prepare_to_wait infrun: proceed: resuming process 1763 infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 1763] at 0x55555555514e infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: 1635.1635.0 [process 1635], infrun: status->kind = exited, status = 0 infrun: handle_inferior_event status->kind = exited, status = 0 [Inferior 1 (process 1635) exited normally] infrun: stop_waiting infrun: stop_all_threads infrun: stop_all_threads, pass=0, iterations=0 infrun: process 1763 executing, need stop infrun: target_wait (-1.0.0, status) = infrun: 1763.1763.0 [process 1763], infrun: status->kind = exited, status = 0 infrun: stop_all_threads status->kind = exited, status = 0 process 1763 [Inferior 2 (process 1763) exited normally] infrun: stop_all_threads, pass=1, iterations=1 infrun: stop_all_threads done (gdb) info inferiors Num Description Executable * 1 /path/to/a.out 2 /path/to/a.out (gdb) info threads No threads. (gdb) ~~~ gdb/ChangeLog: 2019-11-04 Tankut Baris Aktemur * infrun.c (stop_all_threads): Do NOT ignore TARGET_WAITKIND_NO_RESUMED, TARGET_WAITKIND_THREAD_EXITED, TARGET_WAITKIND_EXITED, TARGET_WAITKIND_SIGNALLED wait statuses received from threads we attempt to stop. Change-Id: I7cec98f40283773b79255d998511da434e9cd408 --- M gdb/infrun.c 1 file changed, 29 insertions(+), 2 deletions(-) diff --git a/gdb/infrun.c b/gdb/infrun.c index f628fd1..45aa1d9 100644 --- a/gdb/infrun.c +++ b/gdb/infrun.c @@ -4489,8 +4489,35 @@ || ws.kind == TARGET_WAITKIND_EXITED || ws.kind == TARGET_WAITKIND_SIGNALLED) { - /* All resumed threads exited - or one thread/process exited/signalled. */ + if (event_ptid != minus_one_ptid) + { + thread_info *t = find_thread_ptid (event_ptid); + if (t == nullptr) + { + /* This is the first time we see this thread. */ + t = add_thread (event_ptid); + } + + /* Set the threads as non-executing to avoid infinitely + waiting for them to stop. */ + mark_non_executing_threads (event_ptid, ws); + + if (ws.kind == TARGET_WAITKIND_NO_RESUMED) + { + /* Do nothing. Already marked the threads. */ + } + if (ws.kind == TARGET_WAITKIND_THREAD_EXITED) + delete_thread (t); + else + { + /* TARGET_WAITKIND_EXITED or + TARGET_WAITKIND_SIGNALLED. */ + /* Need to restore the context because + handle_inferior_exit switches it. */ + scoped_restore_current_pspace_and_thread restore; + handle_inferior_exit (event_ptid, ws); + } + } } else {