From patchwork Fri Feb 1 11:20:37 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Alan Hayward X-Patchwork-Id: 31269 Received: (qmail 66234 invoked by alias); 1 Feb 2019 11:20:42 -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 66220 invoked by uid 89); 1 Feb 2019 11:20:42 -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, MIME_BASE64_BLANKS, RCVD_IN_DNSWL_NONE, SPF_HELO_PASS, SPF_PASS autolearn=ham version=3.3.2 spammy=Hx-languages-length:3896 X-HELO: EUR03-AM5-obe.outbound.protection.outlook.com Received: from mail-eopbgr30061.outbound.protection.outlook.com (HELO EUR03-AM5-obe.outbound.protection.outlook.com) (40.107.3.61) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 01 Feb 2019 11:20:40 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=armh.onmicrosoft.com; s=selector1-arm-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=FwWW6PKPqabOYyR1ZEmLqRrJ5/3p5YgcrKfcaB4qd9Q=; b=gaPHlRgOAwHPcstitz+DBk5HZkp+vfUy6YAbzP3vursR1AwP8ep298hGCPzpT6uc1YQufQNdG3kVFNyw2YkhK6egOR79/JQQA7cx4iYC3tsaTZ1mOoHLq9zwcMI16BM2KrERbe5YSQ5UIY2upQNU+ku1rIgxZ7HiRDc7sxTcj00= Received: from DB6PR0802MB2133.eurprd08.prod.outlook.com (10.172.227.22) by DB6PR0802MB2471.eurprd08.prod.outlook.com (10.172.250.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1580.16; Fri, 1 Feb 2019 11:20:37 +0000 Received: from DB6PR0802MB2133.eurprd08.prod.outlook.com ([fe80::acd7:a958:2aaa:562e]) by DB6PR0802MB2133.eurprd08.prod.outlook.com ([fe80::acd7:a958:2aaa:562e%5]) with mapi id 15.20.1580.017; Fri, 1 Feb 2019 11:20:37 +0000 From: Alan Hayward To: Pedro Alves CC: "gdb-patches@sourceware.org" , nd Subject: Re: [PATCH] gdbserver: When attaching, add process before lwps Date: Fri, 1 Feb 2019 11:20:37 +0000 Message-ID: <7F0653B2-0EE2-4242-BE91-C40B055FD169@arm.com> References: <20190125104834.2595-1-alan.hayward@arm.com> <0e75277b-fa80-129d-e82b-3f854bb33124@redhat.com> In-Reply-To: <0e75277b-fa80-129d-e82b-3f854bb33124@redhat.com> authentication-results: spf=none (sender IP is ) smtp.mailfrom=Alan.Hayward@arm.com; received-spf: None (protection.outlook.com: arm.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 Content-ID: MIME-Version: 1.0 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-IsSubscribed: yes > On 25 Jan 2019, at 18:23, Pedro Alves wrote: > > On 01/25/2019 10:48 AM, Alan Hayward wrote: >> The recent BP/WP changes for AArch64 swapping the order in add_lwp() >> so that the process was added before the lwp. This was due to the lwp >> creation requiring the process data. >> >> This also needs changing in linux_attach(). >> >> Fixes gdb.server/ext-attach.exp on Aarch64. >> >> (This regression was hidden due to the racy nature of the gdb.server >> tests - now they are no longer racy it'll be easier to spot. Also >> checked X86). >> >> gdb/gdbserver/ChangeLog: >> >> 2019-01-25 Alan Hayward >> >> * linux-low.c (linux_attach): Add process before lwp. > >> --- >> gdb/gdbserver/linux-low.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c >> index 17cce24d76..1ab2cfb1eb 100644 >> --- a/gdb/gdbserver/linux-low.c >> +++ b/gdb/gdbserver/linux-low.c >> @@ -1188,6 +1188,8 @@ linux_attach (unsigned long pid) >> ptid_t ptid = ptid_t (pid, pid, 0); >> int err; >> >> + proc = linux_add_process (pid, 1); >> + >> /* Attach to PID. We will check for other threads >> soon. */ >> err = linux_attach_lwp (ptid); >> @@ -1198,8 +1200,6 @@ linux_attach (unsigned long pid) >> error ("Cannot attach to process %ld: %s", pid, reason.c_str ()); >> } >> >> - proc = linux_add_process (pid, 1); >> - > > This fails to consider the error conditions. That error call > visible above throws an exception. > > - If GDBserver is already attached to the process, this will > create another process_info object for the already-attached > process, and leave it behind. > > For this case, it would seem better to check whether we're > already attached to a given PID in common code, around > server.c:attach_inferior. Assuming you are suggesting adding a check if the process object exists in gdbserver, rather than adding a new target func which then calls out to /proc. > > - If GDBserver isn't already attached, but the attach fails, > this will likewise leave a stale process_info object behind. > I think I’m probably missing something here, but if the attach fails for any reason then gdbserver will error and exit - so it won’t matter if the object is not deleted? New patch with the above changes. Ok? gdb/gdbserver/ChangeLog: 2019-02-01 Alan Hayward * linux-low.c (linux_attach): Add process before lwp. * server.c (attach_inferior): Check if already attached. diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c index 44016d2310..8c5a51f23c 100644 --- a/gdb/gdbserver/linux-low.c +++ b/gdb/gdbserver/linux-low.c @@ -1188,18 +1188,19 @@ linux_attach (unsigned long pid) ptid_t ptid = ptid_t (pid, pid, 0); int err; + proc = linux_add_process (pid, 1); + /* Attach to PID. We will check for other threads soon. */ err = linux_attach_lwp (ptid); if (err != 0) { - std::string reason = linux_ptrace_attach_fail_reason_string (ptid, err); + remove_process (proc); + std::string reason = linux_ptrace_attach_fail_reason_string (ptid, err); error ("Cannot attach to process %ld: %s", pid, reason.c_str ()); } - proc = linux_add_process (pid, 1); - /* Don't ignore the initial SIGSTOP if we just attached to this process. It will be collected by wait shortly. */ initial_thread = find_thread_ptid (ptid_t (pid, pid, 0)); diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c index f9bfdd7307..e960c10d40 100644 --- a/gdb/gdbserver/server.c +++ b/gdb/gdbserver/server.c @@ -295,6 +295,9 @@ attach_inferior (int pid) /* myattach should return -1 if attaching is unsupported, 0 if it succeeded, and call error() otherwise. */ + if (find_process_pid (pid) != nullptr) + error ("Already attached to process %d\n", pid); + if (myattach (pid) != 0) return -1;