From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.4 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 182DFC4360F for ; Thu, 4 Apr 2019 23:16:47 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CD0FA206DF for ; Thu, 4 Apr 2019 23:16:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CD0FA206DF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([127.0.0.1]:60845 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hCBbC-0008EO-0h for qemu-devel@archiver.kernel.org; Thu, 04 Apr 2019 19:16:46 -0400 Received: from eggs.gnu.org ([209.51.188.92]:37162) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hCBaP-0007oL-Lq for qemu-devel@nongnu.org; Thu, 04 Apr 2019 19:15:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hCBaO-0007ha-EB for qemu-devel@nongnu.org; Thu, 04 Apr 2019 19:15:57 -0400 Received: from mga07.intel.com ([134.134.136.100]:60682) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hCBaO-0007cR-30 for qemu-devel@nongnu.org; Thu, 04 Apr 2019 19:15:56 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 04 Apr 2019 16:15:48 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,309,1549958400"; d="scan'208";a="161533022" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by fmsmga001.fm.intel.com with ESMTP; 04 Apr 2019 16:15:47 -0700 Date: Fri, 5 Apr 2019 07:15:26 +0800 From: Wei Yang To: Markus Armbruster Message-ID: <20190404231526.GA17148@richard> References: <20190311060823.18360-1-richardw.yang@linux.intel.com> <20190402132650.23095-2-armbru@redhat.com> <20190403223255.GB18809@richard> <875zrt69iy.fsf@dusky.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline In-Reply-To: <875zrt69iy.fsf@dusky.pond.sub.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 134.134.136.100 Subject: Re: [Qemu-devel] [PATCH 4/4] vl: Simplify machine_parse() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Wei Yang Cc: pbonzini@redhat.com, Wei Yang , ehabkost@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Message-ID: <20190404231526.k28iSUB_vW1qls0gTrcOQQXj71WCJRX2_zzkmRoImTY@z> On Thu, Apr 04, 2019 at 06:05:25PM +0200, Markus Armbruster wrote: >Wei Yang writes: > >> On Tue, Apr 02, 2019 at 03:26:50PM +0200, Markus Armbruster wrote: >>>Exploit that argument @name is nerver null. Check is_help_option() >>>first, because that's what we do elsewhere. >>> >>>Signed-off-by: Markus Armbruster >>>--- >>> vl.c | 24 +++++++++++------------- >>> 1 file changed, 11 insertions(+), 13 deletions(-) >>> >>>diff --git a/vl.c b/vl.c >>>index 6a31e5bfac..da1af3e10d 100644 >>>--- a/vl.c >>>+++ b/vl.c >>>@@ -2573,19 +2573,10 @@ static gint machine_class_cmp(gconstpointer a, gconstpointer b) >>> >>> static MachineClass *machine_parse(const char *name, GSList *machines) >>> { >>>- MachineClass *mc = NULL; >>>+ MachineClass *mc; >>> GSList *el; >>> >>>- if (name) { >>>- mc = find_machine(name, machines); >>>- } >>>- if (mc) { >>>- return mc; >>>- } >>>- if (name && !is_help_option(name)) { >>>- error_report("unsupported machine type"); >>>- error_printf("Use -machine help to list supported machines\n"); >>>- } else { >>>+ if (is_help_option(name)) { >>> printf("Supported machines are:\n"); >>> machines = g_slist_sort(machines, machine_class_cmp); >>> for (el = machines; el; el = el->next) { >>>@@ -2597,9 +2588,16 @@ static MachineClass *machine_parse(const char *name, GSList *machines) >>> mc->is_default ? " (default)" : "", >>> mc->deprecation_reason ? " (deprecated)" : ""); >>> } >>>+ exit(0); >>> } >>>- >>>- exit(!name || !is_help_option(name)); >>>+ >>>+ mc = find_machine(name, machines); >>>+ if (!mc) { >>>+ error_report("unsupported machine type"); >>>+ error_printf("Use -machine help to list supported machines\n"); >>>+ exit(1); >>>+ } >>>+ return mc; >> >> This change looks changed the original behavior. >> >> In original logic, if mc is not NULL, there is no message printed. While now >> it rely on is_help_option(). And no it exit when !is_help_option(), while >> before this change it exit when is_help_option(). >> >> I don't understand the reason behind this. My suggestion is you may split this >> patch into two: >> >> 1. remove check on name >> 2. refine the logic with explanations. > >Cases: > >(1) User asks for help, i.e. is_help_option(name) > >(1a) and no machine named @name exists, i.e. > is_help_option(name) && !find_machine(name, machines) > >(1b) and a machine named @name exists > is_help_option(name) && find_machine(name, machines) > >(2) User asks for a machine that doesn't exist, i.e. > !is_help_option(name) && !find_machine(name, machines) > >(3) User asks for a machine that exists, i.e. > !is_help_option(name) && find_machine(name, machines) > >Since no machines are called "help" or "?", case (1b) is not actually >possible. > >Old code: > > static MachineClass *machine_parse(const char *name, GSList *machines) > { > MachineClass *mc = NULL; > GSList *el; > > if (name) { > mc = find_machine(name, machines); > } > if (mc) { > return mc; > } > if (name && !is_help_option(name)) { > error_report("unsupported machine type"); > error_printf("Use -machine help to list supported machines\n"); > } else { > printf("Supported machines are:\n"); > machines = g_slist_sort(machines, machine_class_cmp); > for (el = machines; el; el = el->next) { > MachineClass *mc = el->data; > if (mc->alias) { > printf("%-20s %s (alias of %s)\n", mc->alias, mc->desc, mc->name); > } > printf("%-20s %s%s%s\n", mc->name, mc->desc, > mc->is_default ? " (default)" : "", > mc->deprecation_reason ? " (deprecated)" : ""); > } > } > > exit(!name || !is_help_option(name)); > } > >Case (1a): print help, exit(0) > >Case (1b): return find_machine() > >Case (2): report error, exit(1) > >Case (3): return find_machine() > >New code: > > static MachineClass *machine_parse(const char *name, GSList *machines) > { > MachineClass *mc; > GSList *el; > > if (is_help_option(name)) { > printf("Supported machines are:\n"); > machines = g_slist_sort(machines, machine_class_cmp); > for (el = machines; el; el = el->next) { > MachineClass *mc = el->data; > if (mc->alias) { > printf("%-20s %s (alias of %s)\n", mc->alias, mc->desc, mc->name); > } > printf("%-20s %s%s%s\n", mc->name, mc->desc, > mc->is_default ? " (default)" : "", > mc->deprecation_reason ? " (deprecated)" : ""); > } > exit(0); > } > > mc = find_machine(name, machines); > if (!mc) { > error_report("unsupported machine type"); > error_printf("Use -machine help to list supported machines\n"); > exit(1); > } > return mc; > } > >Case (1a): print help, exit(0) > >Case (1b): print help, exit(0) > >Case (2): report error, exit(1) > >Case (3): return find_machine() > >The patch changes "impossible" case (1b). That's intentional (but my >commit message could explain it better). This looks better. Would you mind refine it so that I could send all these patches in v2. Or you prefer send it out by our self? -- Wei Yang Help you, Help me