Message-ID: <BYAPR21MB1688F058773F0D0746E1E3FED7FA9@BYAPR21MB1688.namprd21.prod.outlook.com>
Date:   Thu, 5 Jan 2023 03:27:07 +0000
From:   "Michael Kelley (LINUX)" <mikelley@...rosoft.com>
To:     Dawei Li <set_pte_at@...look.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "wei.liu@...nel.org" <wei.liu@...nel.org>,
        Dexuan Cui <decui@...rosoft.com>
CC:     "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2] hyperv: Make remove callback of hyperv driver void
 returned

From: Dawei Li <set_pte_at@...look.com> Sent: Sunday, January 1, 2023 9:04 PM
> 

Historically, patches for the VMBus drivers in the drivers/hv directory
have a subject prefix of "Drivers: hv:", not "hyperv".  These changes touch
VMBus drivers that are scattered in other source tree directories as well,
but let's still use the "Drivers: hv:" prefix as the best historical precedent.

> Since commit fc7a6209d571 ("bus: Make remove callback return void") forces
> bus_type::remove be void-returned, it doesn't make much sense for any bus
> based driver implementing remove callbalk to return non-void to its caller.
> 
> This change is for hyperv bus based drivers.

VMBus is the name of the bus, so let's reference that instead of just
Hyper-V.  Note the spelling and capitalization of "Hyper-V" and "VMBus".
We're trying to be more consistent going forward. :-)  And following
documented guidance to avoid language like "this patch" or "this
change" in a commit message, I'd suggest this wording:

As such, change the remove function for Hyper-V VMBus based drivers to
return void.

> 
> Signed-off-by: Dawei Li <set_pte_at@...look.com>
> ---
> v1 -> v2
> - Fixed null dereference issue and deprecated comments, based on comments
>   by Liu Wei.
> - Fixed building issue.
> - Rebased on latest hyperv-next.
> 
> v1
> - https://lore.kernel.org/all/TYCP286MB232373567792ED1AC5E0849FCA189@TYCP286MB2323.JPNP286.PROD.OUTLOOK.COM/
> ---
>  drivers/gpu/drm/hyperv/hyperv_drm_drv.c | 4 +---
>  drivers/hid/hid-hyperv.c                | 4 +---
>  drivers/hv/hv_balloon.c                 | 5 +----
>  drivers/hv/hv_util.c                    | 4 +---
>  drivers/input/serio/hyperv-keyboard.c   | 4 +---
>  drivers/net/hyperv/netvsc_drv.c         | 5 ++---
>  drivers/pci/controller/pci-hyperv.c     | 8 ++------
>  drivers/scsi/storvsc_drv.c              | 4 +---
>  drivers/uio/uio_hv_generic.c            | 5 ++---
>  drivers/video/fbdev/hyperv_fb.c         | 5 +----
>  include/linux/hyperv.h                  | 2 +-
>  net/vmw_vsock/hyperv_transport.c        | 4 +---
>  12 files changed, 15 insertions(+), 39 deletions(-)
> 
> diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> index ca127ff797f7..d117fff26d99 100644
> --- a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> +++ b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> @@ -165,7 +165,7 @@ static int hyperv_vmbus_probe(struct hv_device *hdev,
>  	return ret;
>  }
> 
> -static int hyperv_vmbus_remove(struct hv_device *hdev)
> +static void hyperv_vmbus_remove(struct hv_device *hdev)
>  {
>  	struct drm_device *dev = hv_get_drvdata(hdev);
>  	struct hyperv_drm_device *hv = to_hv(dev);
> @@ -176,8 +176,6 @@ static int hyperv_vmbus_remove(struct hv_device *hdev)
>  	hv_set_drvdata(hdev, NULL);
> 
>  	vmbus_free_mmio(hv->mem->start, hv->fb_size);
> -
> -	return 0;
>  }
> 
>  static int hyperv_vmbus_suspend(struct hv_device *hdev)
> diff --git a/drivers/hid/hid-hyperv.c b/drivers/hid/hid-hyperv.c
> index ab57b49a44ed..ef16c2a54362 100644
> --- a/drivers/hid/hid-hyperv.c
> +++ b/drivers/hid/hid-hyperv.c
> @@ -535,7 +535,7 @@ static int mousevsc_probe(struct hv_device *device,
>  }
> 
> 
> -static int mousevsc_remove(struct hv_device *dev)
> +static void mousevsc_remove(struct hv_device *dev)
>  {
>  	struct mousevsc_dev *input_dev = hv_get_drvdata(dev);
> 
> @@ -544,8 +544,6 @@ static int mousevsc_remove(struct hv_device *dev)
>  	hid_hw_stop(input_dev->hid_device);
>  	hid_destroy_device(input_dev->hid_device);
>  	mousevsc_free_device(input_dev);
> -
> -	return 0;
>  }
> 
>  static int mousevsc_suspend(struct hv_device *dev)
> diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
> index cbe43e2567a7..3eece5e5b0a1 100644
> --- a/drivers/hv/hv_balloon.c
> +++ b/drivers/hv/hv_balloon.c
> @@ -2042,7 +2042,7 @@ static int balloon_probe(struct hv_device *dev,
>  	return ret;
>  }
> 
> -static int balloon_remove(struct hv_device *dev)
> +static void balloon_remove(struct hv_device *dev)
>  {
>  	struct hv_dynmem_device *dm = hv_get_drvdata(dev);
>  	struct hv_hotadd_state *has, *tmp;
> @@ -2083,8 +2083,6 @@ static int balloon_remove(struct hv_device *dev)
>  		kfree(has);
>  	}
>  	spin_unlock_irqrestore(&dm_device.ha_lock, flags);
> -
> -	return 0;
>  }
> 
>  static int balloon_suspend(struct hv_device *hv_dev)
> @@ -2164,7 +2162,6 @@ static  struct hv_driver balloon_drv = {
> 
>  static int __init init_balloon_drv(void)
>  {
> -

Nit:  This is a gratuitous whitespace change.  By itself it doesn't
warrant re-spinning the patch, but if you respin to update the
Subject and commit message, it would be good to remove
this as well.

>  	return vmbus_driver_register(&balloon_drv);
>  }
> 
> diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
> index 835e6039c186..24995ac41c86 100644
> --- a/drivers/hv/hv_util.c
> +++ b/drivers/hv/hv_util.c
> @@ -602,7 +602,7 @@ static int util_probe(struct hv_device *dev,
>  	return ret;
>  }
> 
> -static int util_remove(struct hv_device *dev)
> +static void util_remove(struct hv_device *dev)
>  {
>  	struct hv_util_service *srv = hv_get_drvdata(dev);
> 
> @@ -610,8 +610,6 @@ static int util_remove(struct hv_device *dev)
>  		srv->util_deinit();
>  	vmbus_close(dev->channel);
>  	kfree(srv->recv_buffer);
> -
> -	return 0;
>  }
> 
>  /*
> diff --git a/drivers/input/serio/hyperv-keyboard.c b/drivers/input/serio/hyperv-
> keyboard.c
> index d62aefb2e245..31def6ce5157 100644
> --- a/drivers/input/serio/hyperv-keyboard.c
> +++ b/drivers/input/serio/hyperv-keyboard.c
> @@ -369,7 +369,7 @@ static int hv_kbd_probe(struct hv_device *hv_dev,
>  	return error;
>  }
> 
> -static int hv_kbd_remove(struct hv_device *hv_dev)
> +static void hv_kbd_remove(struct hv_device *hv_dev)
>  {
>  	struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
> 
> @@ -378,8 +378,6 @@ static int hv_kbd_remove(struct hv_device *hv_dev)
>  	kfree(kbd_dev);
> 
>  	hv_set_drvdata(hv_dev, NULL);
> -
> -	return 0;
>  }
> 
>  static int hv_kbd_suspend(struct hv_device *hv_dev)
> diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
> index 89eb4f179a3c..025f805e1ed9 100644
> --- a/drivers/net/hyperv/netvsc_drv.c
> +++ b/drivers/net/hyperv/netvsc_drv.c
> @@ -2594,7 +2594,7 @@ static int netvsc_probe(struct hv_device *dev,
>  	return ret;
>  }
> 
> -static int netvsc_remove(struct hv_device *dev)
> +static void netvsc_remove(struct hv_device *dev)
>  {
>  	struct net_device_context *ndev_ctx;
>  	struct net_device *vf_netdev, *net;
> @@ -2603,7 +2603,7 @@ static int netvsc_remove(struct hv_device *dev)
>  	net = hv_get_drvdata(dev);
>  	if (net == NULL) {
>  		dev_err(&dev->device, "No net device to remove\n");
> -		return 0;
> +		return;
>  	}
> 
>  	ndev_ctx = netdev_priv(net);
> @@ -2637,7 +2637,6 @@ static int netvsc_remove(struct hv_device *dev)
> 
>  	free_percpu(ndev_ctx->vf_stats);
>  	free_netdev(net);
> -	return 0;
>  }
> 
>  static int netvsc_suspend(struct hv_device *dev)
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index 583d3aad6908..e46d9a14053f 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -3813,13 +3813,10 @@ static int hv_pci_bus_exit(struct hv_device *hdev, bool
> keep_devs)
>  /**
>   * hv_pci_remove() - Remove routine for this VMBus channel
>   * @hdev:	VMBus's tracking struct for this root PCI bus
> - *
> - * Return: 0 on success, -errno on failure
>   */
> -static int hv_pci_remove(struct hv_device *hdev)
> +static void hv_pci_remove(struct hv_device *hdev)
>  {
>  	struct hv_pcibus_device *hbus;
> -	int ret;
> 
>  	hbus = hv_get_drvdata(hdev);
>  	if (hbus->state == hv_pcibus_installed) {
> @@ -3842,7 +3839,7 @@ static int hv_pci_remove(struct hv_device *hdev)
>  		pci_unlock_rescan_remove();
>  	}
> 
> -	ret = hv_pci_bus_exit(hdev, false);
> +	hv_pci_bus_exit(hdev, false);
> 
>  	vmbus_close(hdev->channel);
> 
> @@ -3855,7 +3852,6 @@ static int hv_pci_remove(struct hv_device *hdev)
>  	hv_put_dom_num(hbus->bridge->domain_nr);
> 
>  	kfree(hbus);
> -	return ret;
>  }
> 
>  static int hv_pci_suspend(struct hv_device *hdev)
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> index 3c5b7e4227b2..02f9d1a6f4ac 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -2092,7 +2092,7 @@ static int storvsc_change_queue_depth(struct scsi_device *sdev, int queue_depth)
>  	return scsi_change_queue_depth(sdev, queue_depth);
>  }
> 
> -static int storvsc_remove(struct hv_device *dev)
> +static void storvsc_remove(struct hv_device *dev)
>  {
>  	struct storvsc_device *stor_device = hv_get_drvdata(dev);
>  	struct Scsi_Host *host = stor_device->host;
> @@ -2108,8 +2108,6 @@ static int storvsc_remove(struct hv_device *dev)
>  	scsi_remove_host(host);
>  	storvsc_dev_remove(dev);
>  	scsi_host_put(host);
> -
> -	return 0;
>  }
> 
>  static int storvsc_suspend(struct hv_device *hv_dev)
> diff --git a/drivers/uio/uio_hv_generic.c b/drivers/uio/uio_hv_generic.c
> index c08a6cfd119f..20d9762331bd 100644
> --- a/drivers/uio/uio_hv_generic.c
> +++ b/drivers/uio/uio_hv_generic.c
> @@ -355,20 +355,19 @@ hv_uio_probe(struct hv_device *dev,
>  	return ret;
>  }
> 
> -static int
> +static void
>  hv_uio_remove(struct hv_device *dev)
>  {
>  	struct hv_uio_private_data *pdata = hv_get_drvdata(dev);
> 
>  	if (!pdata)
> -		return 0;
> +		return;
> 
>  	sysfs_remove_bin_file(&dev->channel->kobj, &ring_buffer_bin_attr);
>  	uio_unregister_device(&pdata->info);
>  	hv_uio_cleanup(dev, pdata);
> 
>  	vmbus_free_ring(dev->channel);
> -	return 0;
>  }
> 
>  static struct hv_driver hv_uio_drv = {
> diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
> index 3ce746a46179..cfa6a7c1eeb3 100644
> --- a/drivers/video/fbdev/hyperv_fb.c
> +++ b/drivers/video/fbdev/hyperv_fb.c
> @@ -1240,8 +1240,7 @@ static int hvfb_probe(struct hv_device *hdev,
>  	return ret;
>  }
> 
> -
> -static int hvfb_remove(struct hv_device *hdev)
> +static void hvfb_remove(struct hv_device *hdev)
>  {
>  	struct fb_info *info = hv_get_drvdata(hdev);
>  	struct hvfb_par *par = info->par;
> @@ -1262,8 +1261,6 @@ static int hvfb_remove(struct hv_device *hdev)
> 
>  	hvfb_putmem(hdev, info);
>  	framebuffer_release(info);
> -
> -	return 0;
>  }
> 
>  static int hvfb_suspend(struct hv_device *hdev)
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index 85f7c5a63aa6..cd5cb9f6fae0 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -1273,7 +1273,7 @@ struct hv_driver {
>  	} dynids;
> 
>  	int (*probe)(struct hv_device *, const struct hv_vmbus_device_id *);
> -	int (*remove)(struct hv_device *);
> +	void (*remove)(struct hv_device *dev);
>  	void (*shutdown)(struct hv_device *);
> 
>  	int (*suspend)(struct hv_device *);
> diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
> index 59c3e2697069..7cb1a9d2cdb4 100644
> --- a/net/vmw_vsock/hyperv_transport.c
> +++ b/net/vmw_vsock/hyperv_transport.c
> @@ -879,13 +879,11 @@ static int hvs_probe(struct hv_device *hdev,
>  	return 0;
>  }
> 
> -static int hvs_remove(struct hv_device *hdev)
> +static void hvs_remove(struct hv_device *hdev)
>  {
>  	struct vmbus_channel *chan = hdev->channel;
> 
>  	vmbus_close(chan);
> -
> -	return 0;
>  }
> 
>  /* hv_sock connections can not persist across hibernation, and all the hv_sock
> --
> 2.25.1

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