On Fri, 2022-12-02 at 05:28 +0000, Tian, Kevin wrote: > > From: Alex Williamson <alex.williamson@xxxxxxxxxx> > > Sent: Friday, December 2, 2022 5:10 AM > > > > > Otherwise what this patch does looks better IMHO: > > > > > > ret = device_register(&dev); > > > if (ret) { > > > put_device(&dev); > > > goto err1; > > > } > > > > > > ... > > > > > > return 0; > > > > > > err2: > > > device_unregister(&dev); > > > err1: > > > earlier_unwind(); > > > > > > > This is essentially what was originally proposed. It could also be > > called a "mixed model", implementing part of the unwind in the > > error > > branch before jumping to the common unwind. As demonstrated below, > > every current vfio driver calling device_register() follows a > > similar > > goto unwind stack as found in the sample drivers, which makes it > > trivially easy to split the device_unregister() call and add a goto > > target in between. > > OK. Actually looking into other users of device_register() I can > see both schemes are used, so... > > > > > Either way, they're equivalent and I'll take whichever version > > addresses all the vfio related use cases and gets acks from their > > maintainers. Thanks, > > ... agree either way is fine. Since your version fixes all vfio > cases, > feel free to include: > > Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx> > > > > > Alex > > > > diff --git a/drivers/s390/cio/vfio_ccw_drv.c > > b/drivers/s390/cio/vfio_ccw_drv.c > > index c2a65808605a..54aba7cceb33 100644 > > --- a/drivers/s390/cio/vfio_ccw_drv.c > > +++ b/drivers/s390/cio/vfio_ccw_drv.c > > @@ -199,8 +199,9 @@ static int vfio_ccw_sch_probe(struct subchannel > > *sch) > > return 0; > > > > out_unreg: > > - device_unregister(&parent->dev); > > + device_del(&parent->dev); > > out_free: > > + put_device(&parent->dev); > > dev_set_drvdata(&sch->dev, NULL); > > return ret; > > } Ugh, sorry. I had this partially right at one point but missed this scenario when fixing the parts I had wrong. This is fine by me, thanks for the fixup: Reviewed-by: Eric Farman <farman@xxxxxxxxxxxxx> > > diff --git a/drivers/s390/crypto/vfio_ap_drv.c > > b/drivers/s390/crypto/vfio_ap_drv.c > > index f43cfeabd2cc..997b524bdd2b 100644 > > --- a/drivers/s390/crypto/vfio_ap_drv.c > > +++ b/drivers/s390/crypto/vfio_ap_drv.c > > @@ -122,7 +122,7 @@ static int vfio_ap_matrix_dev_create(void) > > return 0; > > > > matrix_drv_err: > > - device_unregister(&matrix_dev->device); > > + device_del(&matrix_dev->device); > > matrix_reg_err: > > put_device(&matrix_dev->device); > > matrix_alloc_err: > > diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio- > > mdev/mbochs.c > > index 8b5a3a778a25..e54eb752e1ba 100644 > > --- a/samples/vfio-mdev/mbochs.c > > +++ b/samples/vfio-mdev/mbochs.c > > @@ -1430,7 +1430,7 @@ static int __init mbochs_dev_init(void) > > > > ret = device_register(&mbochs_dev); > > if (ret) > > - goto err_class; > > + goto err_put; > > > > ret = mdev_register_parent(&mbochs_parent, &mbochs_dev, > > &mbochs_driver, > > mbochs_mdev_types, > > @@ -1441,8 +1441,9 @@ static int __init mbochs_dev_init(void) > > return 0; > > > > err_device: > > - device_unregister(&mbochs_dev); > > -err_class: > > + device_del(&mbochs_dev); > > +err_put: > > + put_device(&mbochs_dev); > > class_destroy(mbochs_class); > > err_driver: > > mdev_unregister_driver(&mbochs_driver); > > diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c > > index 721fb06c6413..e8400fdab71d 100644 > > --- a/samples/vfio-mdev/mdpy.c > > +++ b/samples/vfio-mdev/mdpy.c > > @@ -717,7 +717,7 @@ static int __init mdpy_dev_init(void) > > > > ret = device_register(&mdpy_dev); > > if (ret) > > - goto err_class; > > + goto err_put; > > > > ret = mdev_register_parent(&mdpy_parent, &mdpy_dev, > > &mdpy_driver, > > mdpy_mdev_types, > > @@ -728,8 +728,9 @@ static int __init mdpy_dev_init(void) > > return 0; > > > > err_device: > > - device_unregister(&mdpy_dev); > > -err_class: > > + device_del(&mdpy_dev); > > +err_put: > > + put_device(&mdpy_dev); > > class_destroy(mdpy_class); > > err_driver: > > mdev_unregister_driver(&mdpy_driver); > > diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c > > index 3c2a421b9b69..e887de672c52 100644 > > --- a/samples/vfio-mdev/mtty.c > > +++ b/samples/vfio-mdev/mtty.c > > @@ -1330,7 +1330,7 @@ static int __init mtty_dev_init(void) > > > > ret = device_register(&mtty_dev.dev); > > if (ret) > > - goto err_class; > > + goto err_put; > > > > ret = mdev_register_parent(&mtty_dev.parent, &mtty_dev.dev, > > &mtty_driver, mtty_mdev_types, > > @@ -1340,8 +1340,9 @@ static int __init mtty_dev_init(void) > > return 0; > > > > err_device: > > - device_unregister(&mtty_dev.dev); > > -err_class: > > + device_del(&mtty_dev.dev); > > +err_put: > > + put_device(&mtty_dev.dev); > > class_destroy(mtty_dev.vd_class); > > err_driver: > > mdev_unregister_driver(&mtty_driver); >