From patchwork Fri Oct 16 19:30:39 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Machado X-Patchwork-Id: 9195 Received: (qmail 31034 invoked by alias); 16 Oct 2015 19:30:48 -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 31018 invoked by uid 89); 16 Oct 2015 19:30:47 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.3 required=5.0 tests=AWL, BAYES_00, KAM_LOTSOFHASH, RCVD_IN_DNSWL_LOW, SPF_PASS autolearn=ham version=3.3.2 X-HELO: relay1.mentorg.com Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 16 Oct 2015 19:30:45 +0000 Received: from svr-orw-fem-03.mgc.mentorg.com ([147.34.97.39]) by relay1.mentorg.com with esmtp id 1ZnAiA-0005y5-Gi from Luis_Gustavo@mentor.com ; Fri, 16 Oct 2015 12:30:42 -0700 Received: from [172.30.0.107] (147.34.91.1) by svr-orw-fem-03.mgc.mentorg.com (147.34.97.39) with Microsoft SMTP Server id 14.3.224.2; Fri, 16 Oct 2015 12:30:41 -0700 Reply-To: Luis Machado Subject: Re: [PATCH] Make GDB wait for events after handling target File-I/O References: <1440723498-19075-1-git-send-email-lgustavo@codesourcery.com> <55F17EC8.5010906@redhat.com> To: Pedro Alves , From: Luis Machado Message-ID: <5621505F.8080506@codesourcery.com> Date: Fri, 16 Oct 2015 16:30:39 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <55F17EC8.5010906@redhat.com> X-IsSubscribed: yes On 09/10/2015 09:59 AM, Pedro Alves wrote: > On 08/28/2015 01:58 AM, Luis Machado wrote: >> GDB was not behaving correctly with qemu-system debugging: >> >> _ftext () at arm-vector.S:25 >> 25 ldr pc, [pc, #24] @ reset >> (gdb) load >> Loading section .text, size 0xc01c lma 0x0 >> Loading section .eh_frame, size 0x48 lma 0xc01c >> Loading section .ARM.exidx, size 0x8 lma 0xc064 >> Loading section .rodata, size 0x398 lma 0xc070 >> Loading section .data, size 0x8e0 lma 0xc408 >> Start address 0x40, load size 52452 >> Transfer rate: 17074 KB/sec, 1748 bytes/write. >> (gdb) c >> Continuing. >> infrun: clear_proceed_status_thread (Thread 1) >> infrun: proceed (addr=0xffffffff, signal=GDB_SIGNAL_DEFAULT) >> infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [Thread 1] at 0x40 >> Sending packet: $vCont?#49...Ack >> Packet received: >> Packet vCont (verbose-resume) is NOT supported >> Sending packet: $Hc0#db...Ack >> Packet received: OK >> Sending packet: $c#63...Ack >> infrun: infrun_async(1) >> infrun: prepare_to_wait >> infrun: target_wait (-1.0.0, status) = >> infrun: -1.0.0 [Thread 0], >> infrun: status->kind = ignore >> infrun: TARGET_WAITKIND_IGNORE >> infrun: prepare_to_wait >> Packet received: Ffstat,00000001,07fffdb0 >> Sending packet: $M7fffdb0,40:000000000000000000002080000000010000c336000001180000000000000000000000000000000000000200000000000000000055dfb11b55dfb11b55dfb11b#5a...Ack >> Packet received: OK >> Sending packet: $F0#76...Ack >> infrun: target_wait (-1.0.0, status) = >> infrun: -1.0.0 [Thread 0], >> infrun: status->kind = ignore >> infrun: TARGET_WAITKIND_IGNORE >> infrun: prepare_to_wait >> infrun: target_wait (-1.0.0, status) = >> infrun: -1.0.0 [Thread 0], >> infrun: status->kind = no-resumed >> infrun: TARGET_WAITKIND_NO_RESUMED >> infrun: stop_waiting >> infrun: clear_step_over_info >> Sending packet: $qfThreadInfo#bb...Ack >> Packet received: m1 >> Sending packet: $qsThreadInfo#c8...Ack >> Packet received: l >> No unwaited-for children left. >> infrun: infrun_async(0) >> (gdb) c >> Continuing. >> Cannot execute this command while the selected thread is running. >> (gdb) >> Continuing. >> Cannot execute this command while the selected thread is running. >> >> This behavior shows up whenever GDB is in all-stop mode and is handling >> target-initiated File-I/O requests, in the middle of, say, a continue >> request. >> >> When GDB is done handling the File-I/O request, it doesn't set >> rs->waiting_for_stop_reply back to 1, meaning GDB should wait for >> further target events. >> >> This seems to be a latent bug, because in the past this didn't really >> cause any issues. But it seems to have been uncovered by commit >> 567420d10895611e03d5ee65e6b24c16a69a6e99, which explicitly checks >> for rs->waiting_for_stop_reply == 0, triggering the failures above. >> >> The following patch fixes this by setting rs->waiting_for_stop_reply >> back to 1 after handling the target-initiated File-I/O request. >> >> infrun: prepare_to_wait >> Packet received: Ffstat,00000001,07fffdb0 >> Sending packet: $M7fffdb0,40:000000000000000000002080000000010000c336000001180000000000000000000000000000000000000200000000000000000055dfb19e55dfb19e55dfb19e#7b...Ack >> Packet received: OK >> Sending packet: $F0#76...Ack >> infrun: target_wait (-1.0.0, status) = >> infrun: -1.0.0 [Thread 0], >> infrun: status->kind = ignore >> infrun: TARGET_WAITKIND_IGNORE >> infrun: prepare_to_wait >> Packet received: Fisatty,00000001 >> Sending packet: $F1#77...Ack >> infrun: target_wait (-1.0.0, status) = >> infrun: -1.0.0 [Thread 0], >> infrun: status->kind = ignore >> infrun: TARGET_WAITKIND_IGNORE >> infrun: prepare_to_wait >> Packet received: Fwrite,00000001,0000d098,00000004 >> Sending packet: $md098,4#d2...Ack >> Packet received: 3732300a >> 720 >> Sending packet: $F4#7a...Ack >> infrun: target_wait (-1.0.0, status) = >> infrun: -1.0.0 [Thread 0], >> infrun: status->kind = ignore >> infrun: TARGET_WAITKIND_IGNORE >> infrun: prepare_to_wait >> Packet received: Fwrite,00000001,07ffffac,00000011 >> Sending packet: $m7ffffac,11#8e...Ack >> Packet received: 0a2a2a2a204558495420636f646520300a >> >> *** EXIT code 0 >> >> Regression-tested on Ubuntu x86-64 and qemu-system-based debugging >> for arm eabi. >> >> OK? > > This is OK. Though I'd prefer if we removed the: > > /* We got something. */ > rs->waiting_for_stop_reply = 0; > > line, and then cleared waiting_for_stop_reply in both the > > case 'E': > case 'T': case 'S': case 'X': case 'W': > > cases. That'd make the check for waiting_for_stop_reply in > interrupt_query work correctly while inside remote_console_output too: > > case 'O': /* Console output. */ > remote_console_output (buf + 1); > > /* The target didn't really stop; keep waiting. */ > rs->waiting_for_stop_reply = 1; > > Thanks, > Pedro Alves > [now cc-ing the list] How does the attached update look? I did not move this statement: rs->stop_reason = TARGET_STOPPED_BY_NO_REASON; ... since it only makes sense with the right value of rs->waiting_for_stop_reply, but it could also be set within each case statement. 2015-10-16 Luis Machado * remote.c (remote_wait_as): Reset rs->waiting_for_stop_reply when handling 'E', 'T', 'S', 'X' and 'W' packets. Set rs->waiting_for_stop_reply to 1 after handling 'F' packets. diff --git a/gdb/remote.c b/gdb/remote.c index f40f791..87b0b58 100644 --- a/gdb/remote.c +++ b/gdb/remote.c @@ -6635,9 +6635,6 @@ remote_wait_as (ptid_t ptid, struct target_waitstatus *status, int options) rs->stop_reason = TARGET_STOPPED_BY_NO_REASON; - /* We got something. */ - rs->waiting_for_stop_reply = 0; - /* Assume that the target has acknowledged Ctrl-C unless we receive an 'F' or 'O' packet. */ if (buf[0] != 'F' && buf[0] != 'O') @@ -6648,6 +6645,8 @@ remote_wait_as (ptid_t ptid, struct target_waitstatus *status, int options) case 'E': /* Error of some sort. */ /* We're out of sync with the target now. Did it continue or not? Not is more likely, so report a stop. */ + rs->waiting_for_stop_reply = 0; + warning (_("Remote failure reply: %s"), buf); status->kind = TARGET_WAITKIND_STOPPED; status->value.sig = GDB_SIGNAL_0; @@ -6655,10 +6654,19 @@ remote_wait_as (ptid_t ptid, struct target_waitstatus *status, int options) case 'F': /* File-I/O request. */ remote_fileio_request (buf, rs->ctrlc_pending_p); rs->ctrlc_pending_p = 0; + + /* GDB handled the File-I/O request, but the target is running + again. Keep waiting for events. */ + rs->waiting_for_stop_reply = 1; break; case 'T': case 'S': case 'X': case 'W': { - struct stop_reply *stop_reply + struct stop_reply *stop_reply; + + /* There is a stop reply to handle. */ + rs->waiting_for_stop_reply = 0; + + stop_reply = (struct stop_reply *) remote_notif_parse (¬if_client_stop, rs->buf);