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 C94EECAC592 for ; Fri, 19 Sep 2025 09:06:14 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uzX3m-0004Lq-Vz; Fri, 19 Sep 2025 05:05:43 -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 1uzX3k-0004L0-9F for qemu-devel@nongnu.org; Fri, 19 Sep 2025 05:05:40 -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 1uzX3g-0004pJ-2x for qemu-devel@nongnu.org; Fri, 19 Sep 2025 05:05:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758272733; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=e0aD/pmWLEBTl3pMUlG/zKIA3vK/Pf/zu5AnBDTgwtg=; b=bKS604XNM1G4qV5DWjlsa7Bo5jyxIzOCDFbbnRnVRgTy0GbvJLwbF1KAOnqqW2upBjfBV9 RrC6BRrjRa/UwnxGpYMbSs7GFacaZNlfqgK+BqUMQyJtZl4JoeB3gSmtVoUePjBigkbdVG rHhexVFSZjEVJm4nn/8GYsb66gadXpQ= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-520-wHih6RjaNwSOZqk-V34fKw-1; Fri, 19 Sep 2025 05:05:32 -0400 X-MC-Unique: wHih6RjaNwSOZqk-V34fKw-1 X-Mimecast-MFC-AGG-ID: wHih6RjaNwSOZqk-V34fKw_1758272730 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 677CA195608E; Fri, 19 Sep 2025 09:05:30 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.187]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 407C718004A3; Fri, 19 Sep 2025 09:05:25 +0000 (UTC) Date: Fri, 19 Sep 2025 10:05:21 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Hanna Reitz , Kevin Wolf , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Christian Schoenebeck , Richard Henderson , Manos Pitsidianakis , Stefan Weil , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Gerd Hoffmann , Paolo Bonzini , "Dr. David Alan Gilbert" Subject: Re: [PATCH v3 07/20] util: add API to fetch the current thread name Message-ID: References: <20250910180357.320297-1-berrange@redhat.com> <20250910180357.320297-8-berrange@redhat.com> <87y0qa4y3d.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87y0qa4y3d.fsf@pond.sub.org> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 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=-0.005, 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_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=unavailable 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 Fri, Sep 19, 2025 at 10:59:18AM +0200, Markus Armbruster wrote: > Daniel P. Berrangé writes: > > > This will be used to include the thread name in error reports > > in a later patch. It returns a const string stored in a thread > > local to avoid memory allocation when it is called repeatedly > > in a single thread. This makes the assumption that the thread > > name is set at the very start of the thread, which is the case > > when using qemu_thread_create. > > What happens when the assumption is violated? You will get an operating system default thread name, which on Linux will default to the unqualified binary name based on argv[0] > > > Signed-off-by: Daniel P. Berrangé > > --- > > include/qemu/thread.h | 1 + > > meson.build | 21 +++++++++++++++++ > > util/qemu-thread-posix.c | 28 ++++++++++++++++++++++- > > util/qemu-thread-win32.c | 49 ++++++++++++++++++++++++++++++++++++---- > > 4 files changed, 94 insertions(+), 5 deletions(-) > > diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c > > index 275445ed94..fbb94ca97b 100644 > > --- a/util/qemu-thread-posix.c > > +++ b/util/qemu-thread-posix.c > > @@ -18,7 +18,7 @@ > > #include "qemu/tsan.h" > > #include "qemu/bitmap.h" > > > > -#ifdef CONFIG_PTHREAD_SET_NAME_NP > > +#if defined(CONFIG_PTHREAD_SET_NAME_NP) || defined(CONFIG_PTHREAD_GET_NAME_NP) > > #include > > #endif > > > > @@ -532,3 +532,29 @@ void *qemu_thread_join(QemuThread *thread) > > } > > return ret; > > } > > + > > +#ifndef PTHREAD_MAX_NAMELEN_NP > > +#define PTHREAD_MAX_NAMELEN_NP 16 > > Feels a bit tight. 32? On Linux this constant is not defined, but the manpage says The thread name is a meaningful C language string, whose length is restricted to 16 characters, including the terminating null byte ('\0') so I defined the constant to match the non-Linux constant name, but with the Linux documented max length. > > > +#endif > > + > > +static __thread char namebuf[PTHREAD_MAX_NAMELEN_NP]; > > + > > +const char *qemu_thread_get_name(void) > > +{ > > + int rv; > > + if (namebuf[0] != '\0') { > > + return namebuf; > > + } > > + > > +# if defined(CONFIG_PTHREAD_GETNAME_NP) > > + rv = pthread_getname_np(pthread_self(), namebuf, sizeof(namebuf)); > > +# elif defined(CONFIG_PTHREAD_GET_NAME_NP) > > + rv = pthread_get_name_np(pthread_self(), namebuf, sizeof(namebuf)); > > +# else > > + rv = -1; > > +# endif > > + if (rv != 0) { > > + strlcpy(namebuf, "unnamed", G_N_ELEMENTS(namebuf)); > > + } > > + return namebuf; > > +} 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 :|