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 4B9E9CA0ED1 for ; Mon, 18 Aug 2025 16:52:53 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uo363-0001DQ-7C; Mon, 18 Aug 2025 12:52:35 -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 1uo361-0001DE-Ou for qemu-devel@nongnu.org; Mon, 18 Aug 2025 12:52:33 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uo35z-0005Tj-Ku for qemu-devel@nongnu.org; Mon, 18 Aug 2025 12:52:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1755535949; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ReTSi3vkAF7X4w7IO4ddKUE8lc98iPPT+4VLTwNOuro=; b=MFkxTZYnX2VZQAd8/1s73zCZV8TUGCfi7vm5oW1T/Ex0Vf2wqktkwslj7cluXu2AKf3E5V NNqrhKXv5+z5w/2A8o6PHhJFFSX4lTOKKA0bmi3KlGW9c7itDbMbFLg2Sq5yeqxTklrDpg TWTS7QqTSM4tN3qtxusPLTooBAjfaT0= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-408-xERee3kANci_Q2JLV6KXfw-1; Mon, 18 Aug 2025 12:52:28 -0400 X-MC-Unique: xERee3kANci_Q2JLV6KXfw-1 X-Mimecast-MFC-AGG-ID: xERee3kANci_Q2JLV6KXfw_1755535946 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 998DC1800292; Mon, 18 Aug 2025 16:52:26 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.90]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 330D919560B0; Mon, 18 Aug 2025 16:52:22 +0000 (UTC) Date: Mon, 18 Aug 2025 17:52:19 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Alex =?utf-8?Q?Benn=C3=A9e?= , Manos Pitsidianakis , qemu-devel@nongnu.org, Paolo Bonzini , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Markus Armbruster , Gustavo Romero , Pierrick Bouvier Subject: Re: [PATCH RFC] util/error.c: Print backtrace on error Message-ID: References: <20250805-backtrace-v1-1-d189d09b1e92@linaro.org> <87h5ykzout.fsf@draig.linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@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, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Aug 06, 2025 at 12:34:23PM +0100, Daniel P. Berrangé wrote: > On Wed, Aug 06, 2025 at 12:11:38PM +0100, Alex Bennée wrote: > > Daniel P. Berrangé writes: > > > > > On Tue, Aug 05, 2025 at 07:57:38PM +0300, Manos Pitsidianakis wrote: > > >> On Tue, Aug 5, 2025 at 7:49 PM Daniel P. Berrangé wrote: > > >> > > > >> > > > >> > Was there a specific place where you found things hard to debug > > >> > from the error message alone ? I'm sure we have plenty of examples > > >> > of errors that can be improved, but wondering if there are some > > >> > general patterns we're doing badly that would be a good win > > >> > to improve ? > > >> > > >> Some months ago I was debugging a MemoryRegion use-after-free and used > > >> this code to figure out that the free was called from RCU context > > >> instead of the main thread. > > > > > > We give useful names to many (but not neccessarily all) threads that we > > > spawn. Perhaps we should call pthread_getname_np() to fetch the current > > > thread name, and used that as a prefix on the error message we print > > > out, as a bit of extra context ? > > > > Do we always have sensible names for threads or only if we enable the > > option? > > I was surprised to discover we don't name threads by default, only if we > add '-name debug-threads=yes'. I'm struggling to understand why we would > ever want thread naming disabled, if an OS supports it ? > > I'm inclined to deprecate 'debug-threads' and always set the names when > available. FYI, I'm working on a small series that will enable thread names and IDs to be printed by default with errors, and should post it sometime this week. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|