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Wed, 07 Oct 2020 07:57:26 -0400 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-359-YYq1JicLNfi2__YEsmSQZQ-1; Wed, 07 Oct 2020 07:57:19 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6ED9D10BBEC2; Wed, 7 Oct 2020 11:57:18 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id DED4960BEC; Wed, 7 Oct 2020 11:57:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602071841; 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=dOm/tm/s7vlLGUaUhM3KYMR3GBBc1c4+MT8F0OlIOdc=; b=J2V2l6mdYrOzFJe3kcyzMVAQt2G7KoJJ9xF3QnpGm+K+/7WnxDsmLpMLmzkc+UWkCD/Fre 4CBT3pubWz4gAgmywsCk4XnLUnQODq/jKzvKwQDwsIdAqwJGZRr2kDq+tKSWYnUFqzOpGw IONTnuVrcTYdvt2QbheQO3vFUkqR3CA= X-MC-Unique: YYq1JicLNfi2__YEsmSQZQ-1 From: Paolo Bonzini To: qemu-devel@nongnu.org Subject: [PATCH v8 14/17] scsi/scsi-bus: scsi_device_find: don't return unrealized devices Date: Wed, 7 Oct 2020 07:56:57 -0400 Message-Id: <20201007115700.707938-15-pbonzini@redhat.com> In-Reply-To: <20201007115700.707938-1-pbonzini@redhat.com> References: <20201007115700.707938-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com 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; 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charset="utf-8" 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=3D1812399 Suggested-by: Paolo Bonzini Signed-off-by: Maxim Levitsky Reviewed-by: Stefan Hajnoczi Message-Id: <20200913160259.32145-7-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini Message-Id: <20201006123904.610658-11-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini --- hw/scsi/scsi-bus.c | 83 +++++++++++++++++++++++++++++----------------- 1 file changed, 53 insertions(+), 30 deletions(-) diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c index 4ab9811cd8..7599113efe 100644 --- a/hw/scsi/scsi-bus.c +++ b/hw/scsi/scsi-bus.c @@ -24,6 +24,55 @@ static void scsi_target_free_buf(SCSIRequest *req); =20 static int next_scsi_bus; =20 +static SCSIDevice *do_scsi_device_find(SCSIBus *bus, + int channel, int id, int lun, + bool include_unrealized) +{ + BusChild *kid; + SCSIDevice *retval =3D NULL; + + QTAILQ_FOREACH_RCU(kid, &bus->qbus.children, sibling) { + DeviceState *qdev =3D kid->child; + SCSIDevice *dev =3D SCSI_DEVICE(qdev); + + if (dev->channel =3D=3D channel && dev->id =3D=3D id) { + if (dev->lun =3D=3D lun) { + retval =3D dev; + break; + } + + /* + * If we don't find exact match (channel/bus/lun), + * we will return the first device which matches channel/bus + */ + + if (!retval) { + retval =3D dev; + } + } + } + + /* + * 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 && + !qatomic_load_acquire(&retval->qdev.realized)) { + retval =3D NULL; + } + + return retval; +} + +SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int id, int lun) +{ + RCU_READ_LOCK_GUARD(); + return do_scsi_device_find(bus, channel, id, lun, false); +} + static void scsi_device_realize(SCSIDevice *s, Error **errp) { SCSIDeviceClass *sc =3D SCSI_DEVICE_GET_CLASS(s); @@ -137,7 +186,10 @@ static bool scsi_bus_is_address_free(SCSIBus *bus, int channel, int target, int lun, SCSIDevice **p_dev) { - SCSIDevice *d =3D scsi_device_find(bus, channel, target, lun); + SCSIDevice *d; + + RCU_READ_LOCK_GUARD(); + d =3D do_scsi_device_find(bus, channel, target, lun, true); if (d && d->lun =3D=3D lun) { if (p_dev) { *p_dev =3D d; @@ -1570,35 +1622,6 @@ static char *scsibus_get_fw_dev_path(DeviceState *de= v) qdev_fw_name(dev), d->id, d->lun); } =20 -SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int id, int lun) -{ - BusChild *kid; - SCSIDevice *target_dev =3D NULL; - - RCU_READ_LOCK_GUARD(); - QTAILQ_FOREACH_RCU(kid, &bus->qbus.children, sibling) { - DeviceState *qdev =3D kid->child; - SCSIDevice *dev =3D SCSI_DEVICE(qdev); - - if (dev->channel =3D=3D channel && dev->id =3D=3D id) { - if (dev->lun =3D=3D lun) { - 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 =3D dev; - } - } - } - - return target_dev; -} - /* SCSI request list. For simplicity, pv points to the whole device */ =20 static int put_scsi_requests(QEMUFile *f, void *pv, size_t size, --=20 2.26.2