From patchwork Sun Sep 13 16:02:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxim Levitsky X-Patchwork-Id: 305550 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53B1CC43461 for ; Sun, 13 Sep 2020 16:06:07 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id D2038221EB for ; Sun, 13 Sep 2020 16:06:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="PY2t4gQe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D2038221EB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:48342 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kHUVr-0007PN-Tm for qemu-devel@archiver.kernel.org; Sun, 13 Sep 2020 12:05:59 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54330) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kHUTc-0002zg-Ay for qemu-devel@nongnu.org; Sun, 13 Sep 2020 12:03:40 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:52389 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kHUTa-0001QL-4l for qemu-devel@nongnu.org; Sun, 13 Sep 2020 12:03:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600013017; 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=eooT6LB7ovzjpzN2hgMIQmZV2bZrfVq6sunOr1zhhOM=; b=PY2t4gQe8DtDY2gEl744gZKALdgrPNazXY0CPBnrjUG+Wje6h3/OgodJLjyb10ctTzZgFv WKYLLGxSiZtwGB068fNQrHigqYJam+aS66jj47EpW6kpsyt/GJWHcx2J0N00czQIsozuV7 /Na6vuNegdFBsodejF4cVzHSOaLsZlA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-516-tBkGD3mOPuelxnq7RQI50A-1; Sun, 13 Sep 2020 12:03:33 -0400 X-MC-Unique: tBkGD3mOPuelxnq7RQI50A-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EB458107AD64; Sun, 13 Sep 2020 16:03:32 +0000 (UTC) Received: from localhost.localdomain (unknown [10.35.206.72]) by smtp.corp.redhat.com (Postfix) with ESMTP id B7FC619C4F; Sun, 13 Sep 2020 16:03:27 +0000 (UTC) From: Maxim Levitsky To: qemu-devel@nongnu.org Subject: [PATCH v5 6/9] scsi/scsi-bus: scsi_device_find: don't return unrealized devices Date: Sun, 13 Sep 2020 19:02:56 +0300 Message-Id: <20200913160259.32145-7-mlevitsk@redhat.com> In-Reply-To: <20200913160259.32145-1-mlevitsk@redhat.com> References: <20200913160259.32145-1-mlevitsk@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mlevitsk@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=205.139.110.120; envelope-from=mlevitsk@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/13 07:31:48 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -37 X-Spam_score: -3.8 X-Spam_bar: --- X-Spam_report: (-3.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.695, 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_H2=-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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= , Eduardo Habkost , "Michael S. Tsirkin" , Maxim Levitsky , Stefan Hajnoczi , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" The device core first places a device on the bus and then realizes it. Make scsi_device_find avoid returing such devices to avoid races in drivers that use an iothread (currently virtio-scsi) Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1812399 Suggested-by: Paolo Bonzini Signed-off-by: Maxim Levitsky Reviewed-by: Stefan Hajnoczi --- hw/scsi/scsi-bus.c | 89 ++++++++++++++++++++++++++++------------------ 1 file changed, 54 insertions(+), 35 deletions(-) diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c index 92d412b65c..1fbb3ee584 100644 --- a/hw/scsi/scsi-bus.c +++ b/hw/scsi/scsi-bus.c @@ -51,6 +51,57 @@ static const TypeInfo scsi_bus_info = { }; static int next_scsi_bus; +static SCSIDevice *do_scsi_device_find(SCSIBus *bus, + int channel, int id, int lun, + bool include_unrealized) +{ + BusChild *kid; + SCSIDevice *retval = NULL; + + rcu_read_lock(); + + QTAILQ_FOREACH_RCU(kid, &bus->qbus.children, sibling) { + DeviceState *qdev = kid->child; + SCSIDevice *dev = SCSI_DEVICE(qdev); + + if (dev->channel == channel && dev->id == id) { + if (dev->lun == lun) { + retval = dev; + goto out; + } + + /* + * If we don't find exact match (channel/bus/lun), + * we will return the first device which matches channel/bus + */ + + if (!retval) { + retval = dev; + } + } + } +out: + /* + * This function might run on the IO thread and we might race against + * main thread hot-plugging the device. + * We assume that as soon as .realized is set to true we can let + * the user access the device. + */ + + if (retval && !include_unrealized && + !atomic_load_acquire(&retval->qdev.realized)) { + retval = NULL; + } + + rcu_read_unlock(); + return retval; +} + +SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int id, int lun) +{ + return do_scsi_device_find(bus, channel, id, lun, false); +} + static void scsi_device_realize(SCSIDevice *s, Error **errp) { SCSIDeviceClass *sc = SCSI_DEVICE_GET_CLASS(s); @@ -186,7 +237,7 @@ static void scsi_qdev_realize(DeviceState *qdev, Error **errp) dev->lun = 0; } do { - d = scsi_device_find(bus, dev->channel, ++id, dev->lun); + d = do_scsi_device_find(bus, dev->channel, ++id, dev->lun, true); } while (d && d->lun == dev->lun && id < bus->info->max_target); if (d && d->lun == dev->lun) { error_setg(errp, "no free target"); @@ -196,7 +247,7 @@ static void scsi_qdev_realize(DeviceState *qdev, Error **errp) } else if (dev->lun == -1) { int lun = -1; do { - d = scsi_device_find(bus, dev->channel, dev->id, ++lun); + d = do_scsi_device_find(bus, dev->channel, dev->id, ++lun, true); } while (d && d->lun == lun && lun < bus->info->max_lun); if (d && d->lun == lun) { error_setg(errp, "no free lun"); @@ -204,7 +255,7 @@ static void scsi_qdev_realize(DeviceState *qdev, Error **errp) } dev->lun = lun; } else { - d = scsi_device_find(bus, dev->channel, dev->id, dev->lun); + d = do_scsi_device_find(bus, dev->channel, dev->id, dev->lun, true); assert(d); if (d->lun == dev->lun && dev != d) { error_setg(errp, "lun already used by '%s'", d->qdev.id); @@ -1573,38 +1624,6 @@ static char *scsibus_get_fw_dev_path(DeviceState *dev) qdev_fw_name(dev), d->id, d->lun); } -SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int id, int lun) -{ - BusChild *kid; - SCSIDevice *target_dev = NULL; - - rcu_read_lock(); - - QTAILQ_FOREACH_RCU(kid, &bus->qbus.children, sibling) { - DeviceState *qdev = kid->child; - SCSIDevice *dev = SCSI_DEVICE(qdev); - - if (dev->channel == channel && dev->id == id) { - if (dev->lun == lun) { - rcu_read_unlock(); - return dev; - } - - /* - * If we don't find exact match (channel/bus/lun), - * we will return the first device which matches channel/bus - */ - - if (!target_dev) { - target_dev = dev; - } - } - } - - rcu_read_unlock(); - return target_dev; -} - /* SCSI request list. For simplicity, pv points to the whole device */ static int put_scsi_requests(QEMUFile *f, void *pv, size_t size,