From patchwork Wed Feb 5 13:19:27 2020 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: 37695 Received: (qmail 1480 invoked by alias); 5 Feb 2020 13:19:38 -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 1341 invoked by uid 89); 5 Feb 2020 13:19:37 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-26.9 required=5.0 tests=BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3 autolearn=ham version=3.3.1 spammy=Connection, statuses, sends, luis.machado@linaro.org 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; Wed, 05 Feb 2020 13:19:35 +0000 Received: by mx1.osci.io (Postfix, from userid 994) id 9191F208CB; Wed, 5 Feb 2020 08:19:32 -0500 (EST) Received: from gnutoolchain-gerrit.osci.io (gnutoolchain-gerrit.osci.io [IPv6:2620:52:3:1:5054:ff:fe06:16ca]) by mx1.osci.io (Postfix) with ESMTP id 4EA6B20393; Wed, 5 Feb 2020 08:19:28 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by gnutoolchain-gerrit.osci.io (Postfix) with ESMTP id 2697A28170; Wed, 5 Feb 2020 08:19:28 -0500 (EST) X-Gerrit-PatchSet: 3 Date: Wed, 5 Feb 2020 08:19:27 -0500 From: "Tankut Baris Aktemur (Code Review)" To: Luis Machado , Pedro Alves , gdb-patches@sourceware.org Cc: Tom de Vries Auto-Submitted: auto-generated X-Gerrit-MessageType: newpatchset Subject: [review v3] 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: 636a6d2faaea7039d2153661ab81d9e673bb5b73 In-Reply-To: References: Reply-To: tankut.baris.aktemur@intel.com, tdevries@suse.de, palves@redhat.com, luis.machado@linaro.org, gdb-patches@sourceware.org MIME-Version: 1.0 Content-Disposition: inline User-Agent: Gerrit/3.0.3-79-g83ff7f88f1 Message-Id: <20200205131928.2697A28170@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 8564) infrun: clear_proceed_status_thread (process 8652) infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT) infrun: proceed: resuming process 8564 infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 8564] at 0x55555555514e infrun: infrun_async(1) infrun: prepare_to_wait infrun: proceed: resuming process 8652 infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 8652] at 0x55555555514e infrun: prepare_to_wait infrun: Found 2 inferiors, starting at #0 infrun: target_wait (-1.0.0, status) = infrun: 8564.8564.0 [process 8564], infrun: status->kind = exited, status = 0 infrun: handle_inferior_event status->kind = exited, status = 0 [Inferior 1 (process 8564) exited normally] infrun: stop_waiting infrun: stop_all_threads infrun: stop_all_threads, pass=0, iterations=0 infrun: process 8652 executing, need stop infrun: target_wait (-1.0.0, status) = infrun: 8652.8652.0 [process 8652], infrun: status->kind = exited, status = 0 infrun: stop_all_threads status->kind = exited, status = 0 process 8652 infrun: saving status status->kind = exited, status = 0 for 8652.8652.0 infrun: process 8652 not executing infrun: stop_all_threads, pass=1, iterations=1 infrun: process 8652 not executing infrun: stop_all_threads done (gdb) infrun: Using pending wait status status->kind = exited, status = 0 for process 8652. infrun: target_wait (-1.0.0, status) = infrun: 8652.8652.0 [process 8652], infrun: status->kind = exited, status = 0 infrun: handle_inferior_event status->kind = exited, status = 0 [Inferior 2 (process 8652) exited normally] infrun: stop_waiting info inferiors Num Description Connection Executable 1 a.out * 2 a.out (gdb) info threads No threads. (gdb) ~~~ gdb/ChangeLog: 2020-02-05 Tankut Baris Aktemur Tom de Vries PR threads/25478 * 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, 43 insertions(+), 5 deletions(-) diff --git a/gdb/infrun.c b/gdb/infrun.c index 9224376..77c64da 100644 --- a/gdb/infrun.c +++ b/gdb/infrun.c @@ -4799,9 +4799,14 @@ "infrun: %s not executing\n", target_pid_to_str (t->ptid).c_str ()); - /* The thread may be not executing, but still be - resumed with a pending status to process. */ - t->resumed = false; + if ((t->suspend.waitstatus.kind == TARGET_WAITKIND_SIGNALLED + || t->suspend.waitstatus.kind == TARGET_WAITKIND_EXITED) + && t->suspend.waitstatus_pending_p) + ; + else + /* The thread may be not executing, but still be + resumed with a pending status to process. */ + t->resumed = false; } } @@ -4829,8 +4834,41 @@ || event.ws.kind == TARGET_WAITKIND_EXITED || event.ws.kind == TARGET_WAITKIND_SIGNALLED) { - /* All resumed threads exited - or one thread/process exited/signalled. */ + /* Eventing target is null if there were no waitable + targets. */ + if (event.target != nullptr) + { + thread_info *t = find_thread_ptid (event.target, + event.ptid); + /* Check if this is the first time we see this + thread. Don't bother adding if it exited. */ + if (t == nullptr + && event.ws.kind != TARGET_WAITKIND_THREAD_EXITED) + t = add_thread (event.target, event.ptid); + + if (event.ws.kind != TARGET_WAITKIND_THREAD_EXITED) + { + /* Set the threads as non-executing to avoid + another stop attempt on them. */ + mark_non_executing_threads (event.target, event.ptid, + event.ws); + + if (event.ws.kind == TARGET_WAITKIND_NO_RESUMED) + { + /* Do nothing. Already marked the threads. */ + } + else + { + /* TARGET_WAITKIND_EXITED or + TARGET_WAITKIND_SIGNALLED. */ + save_waitstatus (t, &event.ws); + /* This was cleared in mark_non_executing_threads. + Set it so this pending event is considered by + do_target_wait. */ + t->resumed = true; + } + } + } } else {