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 08BFACAC59A for ; Fri, 19 Sep 2025 09:00:12 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uzWxs-0002Ab-0h; Fri, 19 Sep 2025 04:59:37 -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 1uzWxo-0002A2-H8 for qemu-devel@nongnu.org; Fri, 19 Sep 2025 04:59:33 -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 1uzWxi-0002Tv-RU for qemu-devel@nongnu.org; Fri, 19 Sep 2025 04:59:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758272364; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UA6ek8bIu26WxrAxZF9ikIffISjMeEJF4J2xEEg7d+w=; b=ejKwkcH0XaarB0yJ51fbGsCI9xaFr6IoxUob9YA9BbaXToZtRnIivaYYGPFT3ug5O9q0N1 rZZyWm42yIbpgz7mVaA7uW/9xUc2EI/L1+0cE0XjnRIgxeWpBifgLz1vboHO7KkWCtfKMO 8qHuuFK5000XMC1GDi7RcQmT/eUpWeY= Received: from mx-prod-mc-08.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-399-8ZTx2me3OBKgQYKsgS5_Pw-1; Fri, 19 Sep 2025 04:59:23 -0400 X-MC-Unique: 8ZTx2me3OBKgQYKsgS5_Pw-1 X-Mimecast-MFC-AGG-ID: 8ZTx2me3OBKgQYKsgS5_Pw_1758272362 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A4AEB18004D4; Fri, 19 Sep 2025 08:59:21 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.33]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 004BC1800452; Fri, 19 Sep 2025 08:59:20 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 3F13121E6A27; Fri, 19 Sep 2025 10:59:18 +0200 (CEST) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Hanna Reitz , Kevin Wolf , =?utf-8?Q?Marc-Andr?= =?utf-8?Q?=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 In-Reply-To: <20250910180357.320297-8-berrange@redhat.com> ("Daniel P. =?utf-8?Q?Berrang=C3=A9=22's?= message of "Wed, 10 Sep 2025 19:03:44 +0100") References: <20250910180357.320297-1-berrange@redhat.com> <20250910180357.320297-8-berrange@redhat.com> Date: Fri, 19 Sep 2025 10:59:18 +0200 Message-ID: <87y0qa4y3d.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 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=-0.005, 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_H4=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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Daniel P. Berrang=C3=A9 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? > Signed-off-by: Daniel P. Berrang=C3=A9 > --- > 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/include/qemu/thread.h b/include/qemu/thread.h > index 27b888ab0a..98cc5c41ac 100644 > --- a/include/qemu/thread.h > +++ b/include/qemu/thread.h > @@ -216,6 +216,7 @@ void qemu_thread_get_self(QemuThread *thread); > bool qemu_thread_is_self(QemuThread *thread); > G_NORETURN void qemu_thread_exit(void *retval); > void qemu_thread_set_name(const char *name); > +const char *qemu_thread_get_name(void); >=20=20 > struct Notifier; > /** > diff --git a/meson.build b/meson.build > index fa6186db33..6aa673f4b2 100644 > --- a/meson.build > +++ b/meson.build > @@ -2920,6 +2920,27 @@ config_host_data.set('CONFIG_PTHREAD_SET_NAME_NP',= cc.links(osdep_prefix + ''' > pthread_set_name_np(thread, "QEMU"); > return 0; > }''', dependencies: threads)) > + > +config_host_data.set('CONFIG_PTHREAD_GETNAME_NP', cc.links(osdep_prefix = + ''' > + #include > + > + int main(void) > + { > + char buf[16]; > + pthread_getname_np(pthread_self(), buf, sizeof(buf)); > + return 0; > + }''', dependencies: threads)) > +config_host_data.set('CONFIG_PTHREAD_GET_NAME_NP', cc.links(osdep_prefix= + ''' > + #include > + #include > + > + int main(void) > + { > + char buf[16]; > + pthread_get_name_np(pthread_self(), buf, sizeof(buf)); > + return 0; > + }''', dependencies: threads)) > + > config_host_data.set('CONFIG_PTHREAD_CONDATTR_SETCLOCK', cc.links(osdep_= prefix + ''' > #include >=20=20 > 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" >=20=20 > -#ifdef CONFIG_PTHREAD_SET_NAME_NP > +#if defined(CONFIG_PTHREAD_SET_NAME_NP) || defined(CONFIG_PTHREAD_GET_NA= ME_NP) > #include > #endif >=20=20 > @@ -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? > +#endif > + > +static __thread char namebuf[PTHREAD_MAX_NAMELEN_NP]; > + > +const char *qemu_thread_get_name(void) > +{ > + int rv; > + if (namebuf[0] !=3D '\0') { > + return namebuf; > + } > + > +# if defined(CONFIG_PTHREAD_GETNAME_NP) > + rv =3D pthread_getname_np(pthread_self(), namebuf, sizeof(namebuf)); > +# elif defined(CONFIG_PTHREAD_GET_NAME_NP) > + rv =3D pthread_get_name_np(pthread_self(), namebuf, sizeof(namebuf)); > +# else > + rv =3D -1; > +# endif > + if (rv !=3D 0) { > + strlcpy(namebuf, "unnamed", G_N_ELEMENTS(namebuf)); > + } > + return namebuf; > +} > diff --git a/util/qemu-thread-win32.c b/util/qemu-thread-win32.c > index 7a734a7a09..e3789c20d1 100644 > --- a/util/qemu-thread-win32.c > +++ b/util/qemu-thread-win32.c > @@ -19,7 +19,10 @@ >=20=20 > typedef HRESULT (WINAPI *pSetThreadDescription) (HANDLE hThread, > PCWSTR lpThreadDescript= ion); > +typedef HRESULT (WINAPI *pGetThreadDescription) (HANDLE hThread, > + PWSTR *lpThreadDescript= ion); > static pSetThreadDescription SetThreadDescriptionFunc; > +static pGetThreadDescription GetThreadDescriptionFunc; > static HMODULE kernel32_module; >=20=20 > static void __attribute__((__constructor__(QEMU_CONSTRUCTOR_EARLY))) > @@ -28,7 +31,7 @@ qemu_thread_init(void) > qemu_thread_set_name("main"); > } >=20=20 > -static bool load_set_thread_description(void) > +static bool load_thread_description(void) > { > static gsize _init_once =3D 0; >=20=20 > @@ -38,14 +41,17 @@ static bool load_set_thread_description(void) > SetThreadDescriptionFunc =3D > (pSetThreadDescription)GetProcAddress(kernel32_module, > "SetThreadDescript= ion"); > - if (!SetThreadDescriptionFunc) { > + GetThreadDescriptionFunc =3D > + (pGetThreadDescription)GetProcAddress(kernel32_module, > + "GetThreadDescript= ion"); > + if (!SetThreadDescriptionFunc || !GetThreadDescriptionFunc) { > FreeLibrary(kernel32_module); > } > } > g_once_init_leave(&_init_once, 1); > } >=20=20 > - return !!SetThreadDescriptionFunc; > + return !!(SetThreadDescriptionFunc && GetThreadDescriptionFunc); > } >=20=20 > static void error_exit(int err, const char *msg) > @@ -326,7 +332,7 @@ void qemu_thread_set_name(const char *name) > { > g_autofree wchar_t *namew =3D NULL; >=20=20 > - if (!load_set_thread_description()) { > + if (!load_thread_description()) { > return; > } >=20=20 > @@ -412,3 +418,38 @@ bool qemu_thread_is_self(QemuThread *thread) > { > return GetCurrentThreadId() =3D=3D thread->tid; > } > + > +static __thread char namebuf[64]; > + > +const char *qemu_thread_get_name(void) > +{ > + HRESULT hr; > + wchar_t *namew =3D NULL; > + g_autofree char *name =3D NULL; > + > + if (namebuf[0] !=3D '\0') { > + return namebuf; > + } > + > + if (!load_thread_description()) { > + goto error; > + } > + > + hr =3D GetThreadDescriptionFunc(GetCurrentThread(), &namew); > + if (!SUCCEEDED(hr)) { > + goto error; > + } > + > + name =3D g_utf16_to_utf8(namew, -1, NULL, NULL, NULL); > + LocalFree(namew); > + if (!name) { > + goto error; > + } > + > + g_strlcpy(namebuf, name, G_N_ELEMENTS(namebuf)); > + return namebuf; > + > + error: > + strlcpy(namebuf, "unnamed", G_N_ELEMENTS(namebuf)); > + return namebuf; > +}