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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) 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 Received-SPF: pass client-ip=216.205.24.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/07 00:54:30 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.742, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: kwolf@redhat.com, Maxim Levitsky , Stefan Hajnoczi , qemu-block@nongnu.org, mreitz@redhat.com 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 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); 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; + + 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; + break; + } + + /* + * If we don't find exact match (channel/bus/lun), + * we will return the first device which matches channel/bus + */ + + if (!retval) { + retval = 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 = 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 = 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 = scsi_device_find(bus, channel, target, lun); + SCSIDevice *d; + + RCU_READ_LOCK_GUARD(); + d = do_scsi_device_find(bus, channel, target, lun, true); if (d && d->lun == lun) { if (p_dev) { *p_dev = d; @@ -1570,35 +1622,6 @@ 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_GUARD(); - 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) { - 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; - } - } - } - - 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,