From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 72102 invoked by alias); 17 Feb 2016 02:51:01 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 72070 invoked by uid 89); 17 Feb 2016 02:50:57 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=ndx, pulled, 1196, Stop X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Wed, 17 Feb 2016 02:50:56 +0000 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (Postfix) with ESMTPS id 59F20804FE for ; Wed, 17 Feb 2016 02:44:55 +0000 (UTC) Received: from brno.lan (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u1H2ipuL016136 for ; Tue, 16 Feb 2016 21:44:54 -0500 From: Pedro Alves To: gdb-patches@sourceware.org Subject: [PATCH 4/5] gdbserver: Leave already-vCont-resumed threads as they were Date: Wed, 17 Feb 2016 02:51:00 -0000 Message-Id: <1455677091-13683-5-git-send-email-palves@redhat.com> In-Reply-To: <1455677091-13683-1-git-send-email-palves@redhat.com> References: <1455677091-13683-1-git-send-email-palves@redhat.com> X-SW-Source: 2016-02/txt/msg00495.txt.bz2 Currently GDB never sends more than one action per vCont packet, when connected in non-stop mode. A follow up patch will change that, and it exposed a gdbserver problem with the vCont handling. For example, this in non-stop mode: => vCont;s:p1.1;c <= OK Should be equivalent to: => vCont;s:p1.1 <= OK => vCont;c <= OK But gdbserver currently doesn't handle this. In the latter case, "vCont;c" makes gdbserver clobber the previous step request. This patch fixes that. Note the server side must ignore resume actions for the thread that has a pending %Stopped notification (and any other threads with events pending), until GDB acks the notification with vStopped. Otherwise, e.g., the following case is mishandled: #1 => g (or any other packet) #2 <= [registers] #3 <= %Stopped T05 thread:p1.2 #4 => vCont s:p1.1;c #5 <= OK Above, the server must not resume thread p1.2 when it processes the vCont. GDB can't know that p1.2 stopped until it acks the %Stopped notification. (Otherwise it wouldn't send a default "c" action.) (The vCont documentation already specifies this.) Finally, special care must also be given to handling fork/vfork events. A (v)fork event actually tells us that two processes stopped -- the parent and the child. Until we follow the fork, we must not resume the child. Therefore, if we have a pending fork follow, we must not send a global wildcard resume action (vCont;c). We can still send process-wide wildcards though. (The comments above will be added as code comments to gdb in a follow up patch.) gdb/gdbserver/ChangeLog: 2016-02-16 Pedro Alves * linux-low.c (linux_set_resume_request): Ignore resume requests for already-resumed threads. * server.c (in_queued_stop_replies_ptid, in_queued_stop_replies): New functions. * server.h (in_queued_stop_replies): New declaration. --- gdb/gdbserver/linux-low.c | 27 +++++++++++++++++++++++++++ gdb/gdbserver/server.c | 33 ++++++++++++++++++++++++++++++++- gdb/gdbserver/server.h | 4 ++++ 3 files changed, 63 insertions(+), 1 deletion(-) diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c index 8b025bd..2cac4c0 100644 --- a/gdb/gdbserver/linux-low.c +++ b/gdb/gdbserver/linux-low.c @@ -4465,6 +4465,33 @@ linux_set_resume_request (struct inferior_list_entry *entry, void *arg) continue; } + /* Ignore (wildcard) resume requests for already-resumed + requests. */ + if (r->resume[ndx].kind != resume_stop + && thread->last_resume_kind != resume_stop) + { + if (debug_threads) + debug_printf ("already %s LWP %ld at GDB's request\n", + (thread->last_resume_kind + == resume_step) + ? "stepping" + : "continuing", + lwpid_of (thread)); + continue; + } + + /* If the thread has a pending event that has already been + reported to GDBserver core, but GDB has not pulled the + event out of the vStopped queue yet, likewise, ignore the + (wildcard) resume request. */ + if (in_queued_stop_replies (entry->id)) + { + if (debug_threads) + debug_printf ("not resuming LWP %ld: has queued stop reply\n", + lwpid_of (thread)); + continue; + } + lwp->resume = &r->resume[ndx]; thread->last_resume_kind = lwp->resume->kind; diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c index ef715e7..660ee5b 100644 --- a/gdb/gdbserver/server.c +++ b/gdb/gdbserver/server.c @@ -193,6 +193,38 @@ vstop_notif_reply (struct notif_event *event, char *own_buf) prepare_resume_reply (own_buf, vstop->ptid, &vstop->status); } +/* QUEUE_iterate callback helper for in_queued_stop_replies. */ + +static int +in_queued_stop_replies_ptid (QUEUE (notif_event_p) *q, + QUEUE_ITER (notif_event_p) *iter, + struct notif_event *event, + void *data) +{ + ptid_t filter_ptid = *(ptid_t *) data; + struct vstop_notif *vstop_event = (struct vstop_notif *) event; + + if (ptid_match (vstop_event->ptid, filter_ptid)) + return 0; + + /* Don't resume fork children that GDB does not know about yet. */ + if ((vstop_event->status.kind == TARGET_WAITKIND_FORKED + || vstop_event->status.kind == TARGET_WAITKIND_VFORKED) + && ptid_match (vstop_event->status.value.related_pid, filter_ptid)) + return 0; + + return 1; +} + +/* See server.h. */ + +int +in_queued_stop_replies (ptid_t ptid) +{ + return !QUEUE_iterate (notif_event_p, notif_stop.queue, + in_queued_stop_replies_ptid, &ptid); +} + struct notif_server notif_stop = { "vStopped", "Stop", NULL, vstop_notif_reply, @@ -2949,7 +2981,6 @@ handle_v_requests (char *own_buf, int packet_len, int *new_packet_len) if (startswith (own_buf, "vCont;")) { - require_running (own_buf); handle_v_cont (own_buf); return; } diff --git a/gdb/gdbserver/server.h b/gdb/gdbserver/server.h index 3d78fb3..68a3670 100644 --- a/gdb/gdbserver/server.h +++ b/gdb/gdbserver/server.h @@ -119,6 +119,10 @@ extern int handle_target_event (int err, gdb_client_data client_data); /* Get rid of the currently pending stop replies that match PTID. */ extern void discard_queued_stop_replies (ptid_t ptid); +/* Returns true if there's a pending stop reply that matches PTID in + the vStopped notifications queue. */ +extern int in_queued_stop_replies (ptid_t ptid); + #include "remote-utils.h" #include "utils.h" -- 1.9.3