Messages in this thread | | | Subject | Re: [PATCH v5 04/13] s390: vfio-ap: base implementation of VFIO AP device driver | From | Pierre Morel <> | Date | Wed, 13 Jun 2018 14:16:55 +0200 |
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On 13/06/2018 14:12, Cornelia Huck wrote: > On Wed, 13 Jun 2018 14:01:54 +0200 > Pierre Morel <pmorel@linux.ibm.com> wrote: > >> On 13/06/2018 13:14, Cornelia Huck wrote: >>> On Wed, 13 Jun 2018 12:54:40 +0200 >>> Pierre Morel <pmorel@linux.ibm.com> wrote: >>> >>>> On 13/06/2018 09:48, Cornelia Huck wrote: >>>>> On Wed, 13 Jun 2018 09:41:16 +0200 >>>>> Pierre Morel <pmorel@linux.ibm.com> wrote: >>>>> >>>>>> On 07/05/2018 17:11, Tony Krowiak wrote: >>>>>>> Introduces a new AP device driver. This device driver >>>>>>> is built on the VFIO mediated device framework. The framework >>>>>>> provides sysfs interfaces that facilitate passthrough >>>>>>> access by guests to devices installed on the linux host. >>>>>> ...snip... >>>>>> >>>>>>> +static int vfio_ap_matrix_dev_create(void) >>>>>>> +{ >>>>>>> + int ret; >>>>>>> + >>>>>>> + vfio_ap_root_device = root_device_register(VFIO_AP_ROOT_NAME); >>>>>>> + >>>>>>> + if (IS_ERR(vfio_ap_root_device)) { >>>>>>> + ret = PTR_ERR(vfio_ap_root_device); >>>>>>> + goto done; >>>>>>> + } >>>>>>> + >>>>>>> + ap_matrix = kzalloc(sizeof(*ap_matrix), GFP_KERNEL); >>>>>>> + if (!ap_matrix) { >>>>>>> + ret = -ENOMEM; >>>>>>> + goto matrix_alloc_err; >>>>>>> + } >>>>>>> + >>>>>>> + ap_matrix->device.type = &vfio_ap_dev_type; >>>>>>> + dev_set_name(&ap_matrix->device, "%s", VFIO_AP_DEV_NAME); >>>>>>> + ap_matrix->device.parent = vfio_ap_root_device; >>>>>>> + ap_matrix->device.release = vfio_ap_matrix_dev_release; >>>>>>> + ap_matrix->device.driver = &vfio_ap_drv.driver; >>>>>>> + >>>>>>> + ret = device_register(&ap_matrix->device); >>>>>>> + if (ret) >>>>>>> + goto matrix_reg_err; >>>>>>> + >>>>>>> + goto done; >>>>>>> + >>>>>>> +matrix_reg_err: >>>>>>> + put_device(&ap_matrix->device); >>>>>> Did not see this before but here you certainly want to >>>>>> do a kfree and not a put_device. >>>>> No, this must not be a kfree. Once you've tried to register something >>>>> embedding a struct device with the driver core, you need to use >>>>> put_device, as another path may have acquired a reference, even if >>>>> registering ultimately failed. See the comment for device_register(). >>>>> IOW, the code is correct. >>>> learned something again :) , >>>> but still, a kfree is needed for the kzalloc. >>>> Does'nt it? >>> No, the put callback for the embedding structure needs to take care of >>> freeing things. Otherwise it is buggy. >> Seems buggy to me. >> How does the put_device knows if it is embedded and then in what it is >> embedded ? > It does not need to know; the code registering the structure needs to > set up device->release correctly.
yes right, thanks.
> >>> >>>>> >>>>>> >>>>>>> + >>>>>>> +matrix_alloc_err: >>>>>>> + root_device_unregister(vfio_ap_root_device); >>>>>>> + >>>>>>> +done: >>>>>>> + return ret; >>>>>>> +} >>>>>>> + >>>>>>> +static void vfio_ap_matrix_dev_destroy(struct ap_matrix *ap_matrix) >>>>>>> +{ >>>>>>> + device_unregister(&ap_matrix->device); >>>>>>> + root_device_unregister(vfio_ap_root_device); >>>>>> Also here you need a kfree(ap_matrix) too . >>>>> Same here. >>>>> >>
-- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany
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