From patchwork Mon Mar 4 18:17:03 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Emilio Cota X-Patchwork-Id: 10838137 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id ABD6617E9 for ; Mon, 4 Mar 2019 18:20:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7F7742AFFA for ; Mon, 4 Mar 2019 18:20:37 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 284322AFB6; Mon, 4 Mar 2019 18:20:37 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.7 required=2.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 0ECBF2AA9B for ; Mon, 4 Mar 2019 18:20:18 +0000 (UTC) Received: from localhost ([127.0.0.1]:58595 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h0sC7-0001TM-5Q for patchwork-qemu-devel@patchwork.kernel.org; Mon, 04 Mar 2019 13:20:07 -0500 Received: from eggs.gnu.org ([209.51.188.92]:44187) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h0sAN-00088t-2a for qemu-devel@nongnu.org; Mon, 04 Mar 2019 13:18:20 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h0sAL-0000aW-Pc for qemu-devel@nongnu.org; Mon, 04 Mar 2019 13:18:19 -0500 Received: from wout2-smtp.messagingengine.com ([64.147.123.25]:42923) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1h0sAL-0000Yj-88 for qemu-devel@nongnu.org; Mon, 04 Mar 2019 13:18:17 -0500 Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailout.west.internal (Postfix) with ESMTP id F3B3036F9; Mon, 4 Mar 2019 13:18:15 -0500 (EST) Received: from mailfrontend2 ([10.202.2.163]) by compute4.internal (MEProxy); Mon, 04 Mar 2019 13:18:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=braap.org; h= from:to:cc:subject:date:message-id:in-reply-to:references; s= mesmtp; bh=jpSpJgv/NEyq1/csqr0nK/atr0CocP5ov7TLd+G/9Do=; b=w8bvW 5F+GBsp+ltVOdde+o7KFVNeHC55q20ufm/TPhXvyMvpHfYZ8VHK4JdRILEnppEsS WIBjry9LOFwbkQeN1Eu1EPvtEeHwlDt+fQsyl9EhGnPrH4eTA6oDsrWeMAUyzw0b wAJ32qeS49eOK6DSKnFXC+H8X4MDNRZ6mGJ8dI= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:date:from:in-reply-to:message-id :references:subject:to:x-me-proxy:x-me-proxy:x-me-sender :x-me-sender:x-sasl-enc; s=fm2; bh=jpSpJgv/NEyq1/csqr0nK/atr0Coc P5ov7TLd+G/9Do=; b=ZOSCczLz+TKpCGv6VxgbXG/cgwkR/DAM/6qHUnsdlOhNN xckE63G4HAbZmvD1j/Pvn+4MBlUgMN8jixFLyfbR56f0zA64riMG+6uSPnVbEpKL DnSoUFukHDWdRwFXiwdrIUPkb43Atdc9mMGJD7ZG7dkyH5Zv/efXAk/6BBMYloxg yr/DN4cNqpBqzmDjXliKMClrQy5XZfVglZjEm8ltvdO1VUlIvIR4DFYL0Zhk1RqF iAt/J90XLrBwcZXP3lrSkpAk9cZQbswPUrQNcFXQzDwvBeJaZyCg2NVvS5Gk8FnH w6S8pNojYqG0PFv7XXPuNGKBOP0/8kQtR8aNx7klg== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedutddrfedugdduuddtucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvufffkffojghfsedttdertdertddtnecuhfhrohhmpedfgfhmihhlihho ucfirdcuvehothgrfdcuoegtohhtrgessghrrggrphdrohhrgheqnecukfhppeduvdekrd ehledrvddtrddvudeinecurfgrrhgrmhepmhgrihhlfhhrohhmpegtohhtrgessghrrggr phdrohhrghenucevlhhushhtvghrufhiiigvpedt X-ME-Proxy: Received: from localhost (flamenco.cs.columbia.edu [128.59.20.216]) by mail.messagingengine.com (Postfix) with ESMTPA id 1FA9610335; Mon, 4 Mar 2019 13:18:15 -0500 (EST) From: "Emilio G. Cota" To: qemu-devel@nongnu.org Date: Mon, 4 Mar 2019 13:17:03 -0500 Message-Id: <20190304181813.8075-4-cota@braap.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190304181813.8075-1-cota@braap.org> References: <20190304181813.8075-1-cota@braap.org> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 64.147.123.25 Subject: [Qemu-devel] [PATCH v7 03/73] cpu: introduce cpu_mutex_lock/unlock X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?utf-8?q?Alex_Benn=C3=A9e?= , Richard Henderson Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP The few direct users of &cpu->lock will be converted soon. The per-thread bitmap introduced here might seem unnecessary, since a bool could just do. However, once we complete the conversion to per-vCPU locks, we will need to cover the use case where all vCPUs are locked by the same thread, which explains why the bitmap is introduced here. Reviewed-by: Richard Henderson Signed-off-by: Emilio G. Cota --- include/qom/cpu.h | 33 +++++++++++++++++++++++++++++++ cpus.c | 48 +++++++++++++++++++++++++++++++++++++++++++-- stubs/cpu-lock.c | 28 ++++++++++++++++++++++++++ stubs/Makefile.objs | 1 + 4 files changed, 108 insertions(+), 2 deletions(-) create mode 100644 stubs/cpu-lock.c diff --git a/include/qom/cpu.h b/include/qom/cpu.h index 721a324199..44b42d86dd 100644 --- a/include/qom/cpu.h +++ b/include/qom/cpu.h @@ -467,6 +467,39 @@ extern CPUTailQ cpus; extern __thread CPUState *current_cpu; +/** + * cpu_mutex_lock - lock a CPU's mutex + * @cpu: the CPU whose mutex is to be locked + * + * To avoid deadlock, a CPU's mutex must be acquired after the BQL. + */ +#define cpu_mutex_lock(cpu) \ + cpu_mutex_lock_impl(cpu, __FILE__, __LINE__) +void cpu_mutex_lock_impl(CPUState *cpu, const char *file, int line); + +/** + * cpu_mutex_unlock - unlock a CPU's mutex + * @cpu: the CPU whose mutex is to be unlocked + */ +#define cpu_mutex_unlock(cpu) \ + cpu_mutex_unlock_impl(cpu, __FILE__, __LINE__) +void cpu_mutex_unlock_impl(CPUState *cpu, const char *file, int line); + +/** + * cpu_mutex_locked - check whether a CPU's mutex is locked + * @cpu: the CPU of interest + * + * Returns true if the calling thread is currently holding the CPU's mutex. + */ +bool cpu_mutex_locked(const CPUState *cpu); + +/** + * no_cpu_mutex_locked - check whether any CPU mutex is held + * + * Returns true if the calling thread is not holding any CPU mutex. + */ +bool no_cpu_mutex_locked(void); + static inline void cpu_tb_jmp_cache_clear(CPUState *cpu) { unsigned int i; diff --git a/cpus.c b/cpus.c index acd453a3ae..e4b54706ce 100644 --- a/cpus.c +++ b/cpus.c @@ -83,6 +83,47 @@ static unsigned int throttle_percentage; #define CPU_THROTTLE_PCT_MAX 99 #define CPU_THROTTLE_TIMESLICE_NS 10000000 +/* XXX: is this really the max number of CPUs? */ +#define CPU_LOCK_BITMAP_SIZE 2048 + +/* + * Note: we index the bitmap with cpu->cpu_index + 1 so that the logic + * also works during early CPU initialization, when cpu->cpu_index is set to + * UNASSIGNED_CPU_INDEX == -1. + */ +static __thread DECLARE_BITMAP(cpu_lock_bitmap, CPU_LOCK_BITMAP_SIZE); + +bool no_cpu_mutex_locked(void) +{ + return bitmap_empty(cpu_lock_bitmap, CPU_LOCK_BITMAP_SIZE); +} + +void cpu_mutex_lock_impl(CPUState *cpu, const char *file, int line) +{ +/* coverity gets confused by the indirect function call */ +#ifdef __COVERITY__ + qemu_mutex_lock_impl(&cpu->lock, file, line); +#else + QemuMutexLockFunc f = atomic_read(&qemu_mutex_lock_func); + + g_assert(!cpu_mutex_locked(cpu)); + set_bit(cpu->cpu_index + 1, cpu_lock_bitmap); + f(&cpu->lock, file, line); +#endif +} + +void cpu_mutex_unlock_impl(CPUState *cpu, const char *file, int line) +{ + g_assert(cpu_mutex_locked(cpu)); + qemu_mutex_unlock_impl(&cpu->lock, file, line); + clear_bit(cpu->cpu_index + 1, cpu_lock_bitmap); +} + +bool cpu_mutex_locked(const CPUState *cpu) +{ + return test_bit(cpu->cpu_index + 1, cpu_lock_bitmap); +} + bool cpu_is_stopped(CPUState *cpu) { return cpu->stopped || !runstate_is_running(); @@ -92,9 +133,9 @@ static inline bool cpu_work_list_empty(CPUState *cpu) { bool ret; - qemu_mutex_lock(&cpu->lock); + cpu_mutex_lock(cpu); ret = QSIMPLEQ_EMPTY(&cpu->work_list); - qemu_mutex_unlock(&cpu->lock); + cpu_mutex_unlock(cpu); return ret; } @@ -1856,6 +1897,9 @@ void qemu_mutex_lock_iothread_impl(const char *file, int line) { QemuMutexLockFunc bql_lock = atomic_read(&qemu_bql_mutex_lock_func); + /* enforce locking order */ + g_assert(no_cpu_mutex_locked()); + g_assert(!qemu_mutex_iothread_locked()); bql_lock(&qemu_global_mutex, file, line); iothread_locked = true; diff --git a/stubs/cpu-lock.c b/stubs/cpu-lock.c new file mode 100644 index 0000000000..3f07d3a28b --- /dev/null +++ b/stubs/cpu-lock.c @@ -0,0 +1,28 @@ +#include "qemu/osdep.h" +#include "qom/cpu.h" + +void cpu_mutex_lock_impl(CPUState *cpu, const char *file, int line) +{ +/* coverity gets confused by the indirect function call */ +#ifdef __COVERITY__ + qemu_mutex_lock_impl(&cpu->lock, file, line); +#else + QemuMutexLockFunc f = atomic_read(&qemu_mutex_lock_func); + f(&cpu->lock, file, line); +#endif +} + +void cpu_mutex_unlock_impl(CPUState *cpu, const char *file, int line) +{ + qemu_mutex_unlock_impl(&cpu->lock, file, line); +} + +bool cpu_mutex_locked(const CPUState *cpu) +{ + return true; +} + +bool no_cpu_mutex_locked(void) +{ + return true; +} diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs index 269dfa5832..2e47e5edf4 100644 --- a/stubs/Makefile.objs +++ b/stubs/Makefile.objs @@ -4,6 +4,7 @@ stub-obj-y += blockdev-close-all-bdrv-states.o stub-obj-y += clock-warp.o stub-obj-y += cpu-get-clock.o stub-obj-y += cpu-get-icount.o +stub-obj-y += cpu-lock.o stub-obj-y += dump.o stub-obj-y += error-printf.o stub-obj-y += fdset.o