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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1A078C77B73 for ; Mon, 8 May 2023 08:33:34 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pvwIb-0007mQ-5k; Mon, 08 May 2023 04:32:49 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pvwIY-0007lz-G3 for qemu-devel@nongnu.org; Mon, 08 May 2023 04:32:47 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pvwIW-0003Cm-OE for qemu-devel@nongnu.org; Mon, 08 May 2023 04:32:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1683534763; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type; bh=K+3wURYqvKcZpahXwjGg1s/RZJQScidrAbaZoomwtts=; b=HrIcHefxWI53xEQhG2bvyXuiNttz1/+rqhBtEf2kmzlBvUy2ELuentX1XCySOsf24RKHzu hLHAOTeBx7SHzoP+Dy0rtQlep+1kPK8SaM9NAICd3WA5Q4KtYJarhV0tbVxJTF3FtVw2Z5 3fXNXBDg3/QSXh34oXL10fDIJ/YbZrU= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-1-K_0S4deyOnm7xeuXtXr0RQ-1; Mon, 08 May 2023 04:32:41 -0400 X-MC-Unique: K_0S4deyOnm7xeuXtXr0RQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8A77A85A5A3 for ; Mon, 8 May 2023 08:32:41 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.121]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 67DCE40C6F42 for ; Mon, 8 May 2023 08:32:41 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 32A4C21E6924; Mon, 8 May 2023 10:32:40 +0200 (CEST) From: Markus Armbruster To: Paolo Bonzini Cc: qemu-devel@nongnu.org Subject: How can I find problematic uses of error_report() with vrc? Date: Mon, 08 May 2023 10:32:40 +0200 Message-ID: <87v8h3mdef.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Calling error_report() from within a function using Error to return error information is almost always wrong. Example: QMP command qmp_migrate() calls rdma_start_outgoing_migration() calls qemu_rdma_source_init() calls qemu_rdma_reg_control() The first four have an Error **errp parameter, and use it to return error information. Good. The last one does not. Instead, qemu_rdma_reg_control() calls error_report() on failure: error_report("qemu_rdma_reg_control failed"); return -1; Its caller qemu_rdma_source_init() detects the failure and sets an error: ret = qemu_rdma_reg_control(rdma, idx); if (ret) { error_setg(temp, "RDMA ERROR: rdma migration: error registering %d control!", idx); goto err_rdma_source_init; } Because of this, QMP command migrate spams stderr on this particular failure. Inappropriate. Easy enough to fix, but I'm after the error pattern, not a single instance that happened to catch my eye. Problem: find call chains from functions using Error to error_report(). Two sub-problems: 1. Find functions using Error Doesn't have to be perfect. I have a simple Coccinelle script (appended) that spits out some 4400 functions. I run it like $ spatch --sp-file find-error-fns.cocci --macro-file scripts/cocci-macro-file.h `git-grep -Fl 'Error **' \*.[ch]` 2. Find call chains from these functions to error_report() I'm hoping vrc can do that for me. How? Here's my find-error-fns.cocci: @r@ identifier fn, errp; position p; @@ fn@p(..., Error **errp, ...) { ... } @script:python@ fn << r.fn; p << r.p; @@ print(f'{p[0].file}:{p[0].line}:{p[0].column}:{fn}')