Received: by 2002:a25:683:0:0:0:0:0 with SMTP id 125csp3999778ybg; Sun, 7 Jun 2020 18:02:03 -0700 (PDT) X-Google-Smtp-Source: ABdhPJz3CDYDj8wb2AUaAaANpt6fqIuQ4AAwTw2iTuk90IO8JqdVhINYOOEewhKLd2aKZQ6XYMwX X-Received: by 2002:aa7:cd41:: with SMTP id v1mr19711069edw.378.1591578122873; Sun, 07 Jun 2020 18:02:02 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1591578122; cv=none; d=google.com; s=arc-20160816; b=y3MPpaEtwdS0BUg7nBheB1e4fLuZiHCaUANpUGQDKkqFodHAjAHLbQxc7Su56KLLor +6dk9GdyxKmF3KFT9MIUiQVniWiqyqCATVAadNQsWx6XDnEnBu22vmOWJ98TOR8QBStw jA+xrJ85TrhjpBhCGeHfAJq7+lAGhwDgLy2clxTIrZmNGpmxllWhcFD7jjV+ZtKSCNPn ToAZKjQvNcT8x+m6yS7rOXnRjnNItWRtnntsHVzBQqxe93+x4UcYTIbGywQ/uJE1D0p0 zWkTqgLyiX+0M/ejXNgedRa4pyPwPzcpr81+mAUI+pUlt9HYQ1epC8XHeuJ6kAncnycF Pc5A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from; bh=kgpopomRXbaH3IstI33258Eh1S+ATvSha0IdxIUvTcM=; b=r931I3Ls/iQtjlCwaoLAPzWGgC7RC0NBvSIkos/uJzYzpviEGDm7P0sWeV00mCXdb3 bEfBiemGTgLyWs0Tw/dns97VgmqYNQ9AbrFSZsbCIoegcrMmEZl4UCE4bjg2kpJEJLGa nJ2eUjmPuyqo+2DWSZrFK5e3ShVyCEaHrf+bg+sS/rD6ZeN/ljOAomsZ+TV0RI0Qt2PC 48Nz8nDqEXkAPInyDJ6k0/YQXPwmiX8e43hwI7psqOk2QDSXCqyDI2L8lLcYmtMUlujN 1ApC+9qe6XHOW+iCjrBXamc04KlMNsQzLWNbnNPzcdGAKZ2CjlEuRMIHtFanmI6wfpcY FMSA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id e2si7625847edy.212.2020.06.07.18.01.40; Sun, 07 Jun 2020 18:02:02 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729084AbgFHA7G (ORCPT + 99 others); Sun, 7 Jun 2020 20:59:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58488 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729055AbgFHA7A (ORCPT ); Sun, 7 Jun 2020 20:59:00 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 07CC4C08C5C3; Sun, 7 Jun 2020 17:59:00 -0700 (PDT) Received: from [5.158.153.53] (helo=debian-buster-darwi.lab.linutronix.de.) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.80) (envelope-from ) id 1ji67q-00010f-1y; Mon, 08 Jun 2020 02:58:54 +0200 From: "Ahmed S. Darwish" To: Peter Zijlstra , Ingo Molnar , Will Deacon Cc: Thomas Gleixner , "Paul E. McKenney" , "Sebastian A. Siewior" , Steven Rostedt , LKML , "Ahmed S. Darwish" , Paolo Bonzini , kvm@vger.kernel.org Subject: [PATCH v2 17/18] kvm/eventfd: Use sequence counter with associated spinlock Date: Mon, 8 Jun 2020 02:57:28 +0200 Message-Id: <20200608005729.1874024-18-a.darwish@linutronix.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200608005729.1874024-1-a.darwish@linutronix.de> References: <20200519214547.352050-1-a.darwish@linutronix.de> <20200608005729.1874024-1-a.darwish@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A sequence counter write side critical section must be protected by some form of locking to serialize writers. A plain seqcount_t does not contain the information of which lock must be held when entering a write side critical section. Use the new seqcount_spinlock_t data type, which allows to associate a spinlock with the sequence counter. This enables lockdep to verify that the spinlock used for writer serialization is held when the write side critical section is entered. If lockdep is disabled this lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish --- include/linux/kvm_irqfd.h | 2 +- virt/kvm/eventfd.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/kvm_irqfd.h b/include/linux/kvm_irqfd.h index dc1da020305b..dac047abdba7 100644 --- a/include/linux/kvm_irqfd.h +++ b/include/linux/kvm_irqfd.h @@ -42,7 +42,7 @@ struct kvm_kernel_irqfd { wait_queue_entry_t wait; /* Update side is protected by irqfds.lock */ struct kvm_kernel_irq_routing_entry irq_entry; - seqcount_t irq_entry_sc; + seqcount_spinlock_t irq_entry_sc; /* Used for level IRQ fast-path */ int gsi; struct work_struct inject; diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index 67b6fc153e9c..8694a2920ea9 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -303,7 +303,7 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args) INIT_LIST_HEAD(&irqfd->list); INIT_WORK(&irqfd->inject, irqfd_inject); INIT_WORK(&irqfd->shutdown, irqfd_shutdown); - seqcount_init(&irqfd->irq_entry_sc); + seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock); f = fdget(args->fd); if (!f.file) { -- 2.20.1