Re:[PATCH] vdpa: regist vhost-vdpa dev class

Hi Stefano,

Thanks for your quick reply and review, :)

On Thu, Dec 23, 2021 at 03:31:45PM +0800, Yi Wang wrote:

quoted

From: Zhang Min <redacted>

Some applications like kata-containers need to acquire MAJOR/MINOR/DEVNAME
for devInfo [1], so regist vhost-vdpa dev class to expose uevent.

1. https://github.com/kata-containers/kata-containers/blob/main/src/runtime/virtcontainers/device/config/config.go

Signed-off-by: Zhang Min <redacted>
Signed-off-by: Yi Wang <redacted>
---
drivers/vhost/vdpa.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index fb41db3da611..90fbad93e7a2 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c

..

quoted

+    vhost_vdpa_class = class_create(THIS_MODULE, "vhost-vdpa");
+    if (IS_ERR(vhost_vdpa_class)) {
+        r = PTR_ERR(vhost_vdpa_class);
+        pr_warn("vhost vdpa class create error %d,  maybe mod reinserted\n", r);

                                                           ^
double space.

I'm not a native speaker, but I would rephrase the second part to "maybe 
the module is already loaded"

quoted

+        vhost_vdpa_class = NULL;
+        return r;
+    }
+
    r = alloc_chrdev_region(&vhost_vdpa_major, 0, VHOST_VDPA_DEV_MAX,
                "vhost-vdpa");
    if (r)

@@ -1111,6 +1121,7 @@ static int __init vhost_vdpa_init(void)

err_vdpa_register_driver:
    unregister_chrdev_region(vhost_vdpa_major, VHOST_VDPA_DEV_MAX);
err_alloc_chrdev:
+    class_destroy(vhost_vdpa_class);

Should we set `vhost_vdpa_class` to NULL here?

If yes, maybe better to add a new label, and a goto in the 
`class_create` error handling.

Yes, reset to NULL is unnecessary, and pr_warn will not be reached when module
is already loaded, so it's no need too.
There will be a v2 patch which simply return PTR_ERR(vhost_vdpa_class);
Other suggestions are also accepted. 

quoted

    return r;
}