From patchwork Wed Dec 11 13:52:51 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tom Tromey X-Patchwork-Id: 36710 Received: (qmail 100012 invoked by alias); 11 Dec 2019 13:52:55 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 100002 invoked by uid 89); 11 Dec 2019 13:52:55 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-22.2 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, RCVD_IN_DNSWL_NONE, SPF_PASS autolearn=ham version=3.3.1 spammy= X-HELO: rock.gnat.com Received: from rock.gnat.com (HELO rock.gnat.com) (205.232.38.15) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 11 Dec 2019 13:52:53 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by filtered-rock.gnat.com (Postfix) with ESMTP id F21B9116132; Wed, 11 Dec 2019 08:52:51 -0500 (EST) Received: from rock.gnat.com ([127.0.0.1]) by localhost (rock.gnat.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id KQCB4uxcnjRz; Wed, 11 Dec 2019 08:52:51 -0500 (EST) Received: from murgatroyd (75-166-123-50.hlrn.qwest.net [75.166.123.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by rock.gnat.com (Postfix) with ESMTPSA id 953D711611C; Wed, 11 Dec 2019 08:52:51 -0500 (EST) From: Tom Tromey To: Simon Marchi Cc: Tom Tromey , gdb-patches@sourceware.org Subject: Re: [PATCH] Fix build on macOS References: <20191210214717.25680-1-tromey@adacore.com> <0aa60cb1-2138-6568-f99a-a9f54fa39f45@simark.ca> Date: Wed, 11 Dec 2019 06:52:51 -0700 In-Reply-To: <0aa60cb1-2138-6568-f99a-a9f54fa39f45@simark.ca> (Simon Marchi's message of "Tue, 10 Dec 2019 20:37:15 -0500") Message-ID: <87sglrdl58.fsf@tromey.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 >>>>> "Simon" == Simon Marchi writes: Simon> I think a version without templates would make it a bit simpler to understand: Yeah, duh. I wonder why I thought that was needed. Fixing this taught me that the macOS man page for pthread_setname_np is incorrect, in that it says the function returns void, whereas declares it returning int. Here's v2. Tom commit 3e82417785ea486a2b683e7d7a0cbda88bca1e9a Author: Tom Tromey Date: Tue Dec 10 14:16:19 2019 -0700 Fix build on macOS PR build/25268 points out that the build fails on macOS, because on macOS the "pthread_setname_np" function takes a single argument. This patch fixes the problem, by introducing a new adapter function that handles both styles of pthread_setname_np. This change also meant moving the pthread_setname_np call to the thread function, because macOS only permits setting the name of the current thread. This means that there can be a brief window when gdb will see the wrong name; but I think this is a minor concern. Tested by rebuilding on x86-64 Fedora 30, and on macOS High Sierra. On Linux I also debugged gdb to ensure that the thread names are still set correctly. gdb/ChangeLog 2019-12-10 Tom Tromey PR build/25268: * gdbsupport/thread-pool.c (set_thread_name): New function. (thread_pool::set_thread_count): Don't call pthread_setname_np. (thread_pool::thread_function): Call set_thread_name. Change-Id: Id7bf28d99ca27a893a9fc87ebb90b15a9c2a9cb4 diff --git a/gdb/ChangeLog b/gdb/ChangeLog index c4e8109b7c5..223a973ccd1 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,10 @@ +2019-12-10 Tom Tromey + + PR build/25268: + * gdbsupport/thread-pool.c (set_thread_name): New function. + (thread_pool::set_thread_count): Don't call pthread_setname_np. + (thread_pool::thread_function): Call set_thread_name. + 2019-12-10 Christian Biesinger * gdbsupport/safe-strerror.c: Supress the unused function warning diff --git a/gdb/gdbsupport/thread-pool.c b/gdb/gdbsupport/thread-pool.c index d19ae02e3ef..7c63fc6aa02 100644 --- a/gdb/gdbsupport/thread-pool.c +++ b/gdb/gdbsupport/thread-pool.c @@ -25,6 +25,7 @@ #include "gdbsupport/alt-stack.h" #include "gdbsupport/block-signals.h" #include +#include "diagnostics.h" /* On the off chance that we have the pthread library on a Windows host, but std::thread is not using it, avoid calling @@ -36,8 +37,31 @@ #endif #ifdef USE_PTHREAD_SETNAME_NP + #include -#endif + +DIAGNOSTIC_PUSH +DIAGNOSTIC_IGNORE_UNUSED_FUNCTION + +/* Handle platform discrepancies in pthread_setname_np: macOS uses a + single-argument form, while Linux uses a two-argument form. This + wrapper template handles the difference. */ + +static void +set_thread_name (int (*set_name) (pthread_t, const char *), const char *name) +{ + set_name (pthread_self (), name); +} + +static void +set_thread_name (void (*set_name) (const char *), const char *name) +{ + set_name (name); +} + +DIAGNOSTIC_POP + +#endif /* USE_PTHREAD_SETNAME_NP */ namespace gdb { @@ -75,9 +99,6 @@ thread_pool::set_thread_count (size_t num_threads) for (size_t i = m_thread_count; i < num_threads; ++i) { std::thread thread (&thread_pool::thread_function, this); -#ifdef USE_PTHREAD_SETNAME_NP - pthread_setname_np (thread.native_handle (), "gdb worker"); -#endif thread.detach (); } } @@ -115,6 +136,12 @@ thread_pool::post_task (std::function func) void thread_pool::thread_function () { +#ifdef USE_PTHREAD_SETNAME_NP + /* This must be done here, because on macOS one can only set the + name of the current thread. */ + set_thread_name (pthread_setname_np, "gdb worker"); +#endif + /* Ensure that SIGSEGV is delivered to an alternate signal stack. */ gdb::alternate_signal_stack signal_stack;