From: Michael Kelley Sent: Wednesday, November 6, 2024 10:36 AM
> From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Sent: Tuesday, November 5, 2024
> 9:45 AM
> >
> > Saurabh Singh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx> writes:
> >
> > > On Mon, Nov 04, 2024 at 05:48:24PM +0100, Vitaly Kuznetsov wrote:
> > >> It was found that unloading 'hid_hyperv' module results in a devres
> > >> complaint:
> > >>
> > >> ...
> > >> hv_vmbus: unregistering driver hid_hyperv
> > >> ------------[ cut here ]------------
> > >> WARNING: CPU: 2 PID: 3983 at drivers/base/devres.c:691
> devres_release_group+0x1f2/0x2c0
> > >> ...
> > >> Call Trace:
> > >> <TASK>
> > >> ? devres_release_group+0x1f2/0x2c0
> > >> ? __warn+0xd1/0x1c0
> > >> ? devres_release_group+0x1f2/0x2c0
> > >> ? report_bug+0x32a/0x3c0
> > >> ? handle_bug+0x53/0xa0
> > >> ? exc_invalid_op+0x18/0x50
> > >> ? asm_exc_invalid_op+0x1a/0x20
> > >> ? devres_release_group+0x1f2/0x2c0
> > >> ? devres_release_group+0x90/0x2c0
> > >> ? rcu_is_watching+0x15/0xb0
> > >> ? __pfx_devres_release_group+0x10/0x10
> > >> hid_device_remove+0xf5/0x220
> > >> device_release_driver_internal+0x371/0x540
> > >> ? klist_put+0xf3/0x170
> > >> bus_remove_device+0x1f1/0x3f0
> > >> device_del+0x33f/0x8c0
> > >> ? __pfx_device_del+0x10/0x10
> > >> ? cleanup_srcu_struct+0x337/0x500
> > >> hid_destroy_device+0xc8/0x130
> > >> mousevsc_remove+0xd2/0x1d0 [hid_hyperv]
> > >> device_release_driver_internal+0x371/0x540
> > >> driver_detach+0xc5/0x180
> > >> bus_remove_driver+0x11e/0x2a0
> > >> ? __mutex_unlock_slowpath+0x160/0x5e0
> > >> vmbus_driver_unregister+0x62/0x2b0 [hv_vmbus]
> > >> ...
> > >>
> > >> And the issue seems to be that the corresponding devres group is not
> > >> allocated. Normally, devres_open_group() is called from
> > >> __hid_device_probe() but Hyper-V HID driver overrides 'hid_dev->driver'
> > >> with 'mousevsc_hid_driver' stub and basically re-implements
> > >> __hid_device_probe() by calling hid_parse() and hid_hw_start() but not
> > >> devres_open_group(). hid_device_probe() does not call __hid_device_probe()
> > >> for it. Later, when the driver is removed, hid_device_remove() calls
> > >> devres_release_group() as it doesn't check whether hdev->driver was
> > >> initially overridden or not.
> > >>
> > >> The issue seems to be related to the commit 62c68e7cee33 ("HID: ensure
> > >> timely release of driver-allocated resources") but the commit itself seems
> > >> to be correct.
> > >>
> > >> Fix the issue by dropping the 'hid_dev->driver' override and the
> > >> now unneeded hid_parse()/hid_hw_start() calls. One notable difference of
> > >> the change is hid_hw_start() is now called with HID_CONNECT_DEFAULT which
> > >> implies HID_CONNECT_HIDRAW. This doesn't seem to cause any immediate issues
> > >> but 'HID_CONNECT_HIDINPUT | HID_CONNECT_HIDDEV' combo was used in the
> > >> driver for a long time and it is unclear whether hidraw was excluded on
> > >> purpose or not.
> > >>
> > >> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> > >
> > > A fixme tag would be helpful.
> >
> > I concluded that it's the unusual 'hid_dev->driver' override in
> > hid-hyperv to blame and not the 62c68e7cee33 ("HID: ensure timely
> > release of driver-allocated resources") but the override was there since
> > the inception of the driver so I'm not sure, mentioning 62c68e7cee33
> > probably makes more sense...
>
> I've finished looking at the linux-next issue in detail, and I agree that
> the hid_dev->driver override is the underlying cause. I was
> commenting out that line Monday night, but had not gotten as far as
> removing the the hid_parse() and hid_hw_start(). Then your patch
> came out, Vitaly, which is great!
>
> >
> > >
> > >> ---
> > >> drivers/hid/hid-hyperv.c | 17 -----------------
> > >> 1 file changed, 17 deletions(-)
> > >>
> > >> diff --git a/drivers/hid/hid-hyperv.c b/drivers/hid/hid-hyperv.c
> > >> index f33485d83d24..1609a56ffa7c 100644
> > >> --- a/drivers/hid/hid-hyperv.c
> > >> +++ b/drivers/hid/hid-hyperv.c
> > >> @@ -431,8 +431,6 @@ static const struct hid_ll_driver mousevsc_ll_driver = {
> > >> .raw_request = mousevsc_hid_raw_request,
> > >> };
> > >>
> > >> -static struct hid_driver mousevsc_hid_driver;
> > >> -
> > >> static int mousevsc_probe(struct hv_device *device,
> > >> const struct hv_vmbus_device_id *dev_id)
> > >> {
> > >> @@ -473,7 +471,6 @@ static int mousevsc_probe(struct hv_device *device,
> > >> }
> > >>
> > >> hid_dev->ll_driver = &mousevsc_ll_driver;
> > >> - hid_dev->driver = &mousevsc_hid_driver;
> > >> hid_dev->bus = BUS_VIRTUAL;
> > >> hid_dev->vendor = input_dev->hid_dev_info.vendor;
> > >> hid_dev->product = input_dev->hid_dev_info.product;
> > >> @@ -488,20 +485,6 @@ static int mousevsc_probe(struct hv_device *device,
> > >> if (ret)
> > >> goto probe_err2;
> > >>
> > >> -
> > >> - ret = hid_parse(hid_dev);
> > >> - if (ret) {
> > >> - hid_err(hid_dev, "parse failed\n");
> > >> - goto probe_err2;
> > >> - }
> > >> -
> > >> - ret = hid_hw_start(hid_dev, HID_CONNECT_HIDINPUT |
> HID_CONNECT_HIDDEV);
>
> As you noted, using HID_CONNECT_DEFAULT in the default probe function
> __hid_device_probe() ends up adding HID_CONNECT_HIDRAW and HID_CONNECT_FF.
> The latter is benign as it only affects devices that support force-feedback. As best I
> can tell, HID_CNNECT_HIDRAW causes /dev/hidraw0 to appear, which provides a raw
> interface to the mouse device. See https://docs.kernel.org/hid/hidraw.html. It doesn't
> seem like making this interface visible hurts anything, but I'm not 100% sure.
>
> The alternative is to keep the "struct hid_driver mousevsc_hid_driver;" line
> and to populate it with a name, id_table, and an HID probe function specific
> to the Hyper-V mouse. Then instead of the incorrect assignment to
> hid_dev->driver, add a
>
> module_hid_driver(mousevsc_hid_driver);
>
> statement, which registers the driver. The new HID probe function does
> the hid_parse() and hid_hw_start() which have been removed from
> mousevsc_probe() as your patch does. With this arrangement, the
> hid_hw_start() can be done with the desired HID_CONNECT_*
> options so that /dev/hidraw0 won't appear. It's only a few lines
> of code.
>
> I can try to code up this approach if it is preferred. But I'm likely tied
> up with some personal things for the next few days, so might not get
> to it for a little while. Feel free to try it yourself if you want.
Here's what I had in mind. It appears to work and preserves the
custom aspects of the current code in mousevsc_probe(). Turns
out I can't use module_hid_driver() because it conflicts with the
existing module_init() and module_exit() use, so I've directly
coded hid_register/unregister_driver().
diff --git a/drivers/hid/hid-hyperv.c b/drivers/hid/hid-hyperv.c
index f33485d83d24..98a7fa09c4ee 100644
--- a/drivers/hid/hid-hyperv.c
+++ b/drivers/hid/hid-hyperv.c
@@ -422,6 +422,25 @@ static int mousevsc_hid_raw_request(struct hid_device *hid,
return 0;
}
+static int mousevsc_hid_probe(struct hid_device *hid_dev, const struct hid_device_id *id)
+{
+ int ret;
+
+ ret = hid_parse(hid_dev);
+ if (ret) {
+ hid_err(hid_dev, "parse failed\n");
+ return ret;
+ }
+
+ ret = hid_hw_start(hid_dev, HID_CONNECT_HIDINPUT | HID_CONNECT_HIDDEV);
+ if (ret) {
+ hid_err(hid_dev, "hw start failed\n");
+ return ret;
+ }
+
+ return 0;
+}
+
static const struct hid_ll_driver mousevsc_ll_driver = {
.parse = mousevsc_hid_parse,
.open = mousevsc_hid_open,
@@ -431,7 +450,16 @@ static const struct hid_ll_driver mousevsc_ll_driver = {
.raw_request = mousevsc_hid_raw_request,
};
-static struct hid_driver mousevsc_hid_driver;
+static const struct hid_device_id mousevsc_devices[] = {
+ { HID_DEVICE(BUS_VIRTUAL, HID_GROUP_ANY, 0x045E, 0x0621) },
+ { }
+};
+
+static struct hid_driver mousevsc_hid_driver = {
+ .name = "hid-hyperv",
+ .id_table = mousevsc_devices,
+ .probe = mousevsc_hid_probe,
+};
static int mousevsc_probe(struct hv_device *device,
const struct hv_vmbus_device_id *dev_id)
@@ -473,7 +501,6 @@ static int mousevsc_probe(struct hv_device *device,
}
hid_dev->ll_driver = &mousevsc_ll_driver;
- hid_dev->driver = &mousevsc_hid_driver;
hid_dev->bus = BUS_VIRTUAL;
hid_dev->vendor = input_dev->hid_dev_info.vendor;
hid_dev->product = input_dev->hid_dev_info.product;
@@ -488,20 +515,6 @@ static int mousevsc_probe(struct hv_device *device,
if (ret)
goto probe_err2;
-
- ret = hid_parse(hid_dev);
- if (ret) {
- hid_err(hid_dev, "parse failed\n");
- goto probe_err2;
- }
-
- ret = hid_hw_start(hid_dev, HID_CONNECT_HIDINPUT | HID_CONNECT_HIDDEV);
-
- if (ret) {
- hid_err(hid_dev, "hw start failed\n");
- goto probe_err2;
- }
-
device_init_wakeup(&device->device, true);
input_dev->connected = true;
@@ -579,11 +592,21 @@ static struct hv_driver mousevsc_drv = {
static int __init mousevsc_init(void)
{
- return vmbus_driver_register(&mousevsc_drv);
+ int ret;
+
+ ret = vmbus_driver_register(&mousevsc_drv);
+ if (ret)
+ return ret;
+
+ ret = hid_register_driver(&mousevsc_hid_driver);
+ if (ret)
+ vmbus_driver_unregister(&mousevsc_drv);
+ return ret;
}
static void __exit mousevsc_exit(void)
{
+ hid_unregister_driver(&mousevsc_hid_driver);
vmbus_driver_unregister(&mousevsc_drv);
}
Michael
