From nobody Sun Feb 8 17:48:04 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1638269564037927.9957846487307; Tue, 30 Nov 2021 02:52:44 -0800 (PST) Received: from localhost ([::1]:57400 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ms0kc-0006Ir-Vx for importer@patchew.org; Tue, 30 Nov 2021 05:52:43 -0500 Received: from eggs.gnu.org ([209.51.188.92]:43640) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ms0aQ-000610-MU for qemu-devel@nongnu.org; Tue, 30 Nov 2021 05:42:10 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:36301) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ms0aO-00013p-3K for qemu-devel@nongnu.org; Tue, 30 Nov 2021 05:42:10 -0500 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-343-wjfPuAIbOdS7oPvOWtH9Nw-1; Tue, 30 Nov 2021 05:42:02 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5490F86A063; Tue, 30 Nov 2021 10:42:01 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.39.193.9]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4DCF910114AE; Tue, 30 Nov 2021 10:41:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1638268927; 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=e29Gggx2QJ++Sey6LRiwKPCe4BhS91CgAJ0+aKHqpRE=; b=fEdPYT7pqoH6TbPO4CU3yHHxgn7g0sIx9LQP8SjTaDyNEhcQ8HkszqpgXYmrzfOiZDqr3W RlJZxKy7lHzAkDyScxBcg4mpX6k0MRwtom2UG0hpjmOpmEIOwU6YT56wzPkeR5moHp+Cgc bb0VVaarO3Oo/zbct6MX2YCzpLXVI0k= X-MC-Unique: wjfPuAIbOdS7oPvOWtH9Nw-1 From: David Hildenbrand To: qemu-devel@nongnu.org Subject: [PATCH v1 6/8] util/oslib-posix: Support concurrent os_mem_prealloc() invocation Date: Tue, 30 Nov 2021 11:41:34 +0100 Message-Id: <20211130104136.40927-7-david@redhat.com> In-Reply-To: <20211130104136.40927-1-david@redhat.com> References: <20211130104136.40927-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.716, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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: , Cc: Pankaj Gupta , Gavin Shan , =?UTF-8?q?Daniel=20P=20=2E=20Berrang=C3=A9?= , Eduardo Habkost , "Michael S. Tsirkin" , =?UTF-8?q?Michal=20Pr=C3=ADvozn=C3=ADk?= , David Hildenbrand , "Dr . David Alan Gilbert" , Pankaj Gupta , Sebastien Boeuf , Igor Mammedov , Paolo Bonzini , Hui Zhu Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1638269565928100001 Add a mutex to protect the SIGBUS case, as we cannot mess concurrently with the sigbus handler and we have to manage the global variable sigbus_memset_context. The MADV_POPULATE_WRITE path can run concurrently. Note that page_mutex and page_cond are shared between concurrent invocations, which shouldn't be a problem. This is a preparation for future virtio-mem prealloc code, which will call os_mem_prealloc() asynchronously from an iothread when handling guest requests. Reviewed-by: Pankaj Gupta Reviewed-by: Daniel P. Berrang=C3=A9 Signed-off-by: David Hildenbrand --- util/oslib-posix.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/util/oslib-posix.c b/util/oslib-posix.c index efa4f96d56..9829149e4b 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -95,6 +95,7 @@ typedef struct MemsetThread MemsetThread; =20 /* used by sigbus_handler() */ static MemsetContext *sigbus_memset_context; +static QemuMutex sigbus_mutex; =20 static QemuMutex page_mutex; static QemuCond page_cond; @@ -625,6 +626,7 @@ static bool madv_populate_write_possible(char *area, si= ze_t pagesize) void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus, Error **errp) { + static gsize initialized; int ret; struct sigaction act, oldact; size_t hpagesize =3D qemu_fd_getpagesize(fd); @@ -638,6 +640,12 @@ void os_mem_prealloc(int fd, char *area, size_t memory= , int smp_cpus, use_madv_populate_write =3D madv_populate_write_possible(area, hpagesi= ze); =20 if (!use_madv_populate_write) { + if (g_once_init_enter(&initialized)) { + qemu_mutex_init(&sigbus_mutex); + g_once_init_leave(&initialized, 1); + } + + qemu_mutex_lock(&sigbus_mutex); memset(&act, 0, sizeof(act)); act.sa_handler =3D &sigbus_handler; act.sa_flags =3D 0; @@ -665,6 +673,7 @@ void os_mem_prealloc(int fd, char *area, size_t memory,= int smp_cpus, perror("os_mem_prealloc: failed to reinstall signal handler"); exit(1); } + qemu_mutex_unlock(&sigbus_mutex); } } =20 --=20 2.31.1