[PATCH bpf-next v5 05/17] HID: core: store the unique system identifier in hid_device

Benjamin Tissoires
2022-05-18T21:00:22Z

This unique identifier is currently used only for ensuring uniqueness in
sysfs. However, this could be handful for userspace to refer to a specific
hid_device by this id.

2 use cases are in my mind: LEDs (and their naming convention), and
HID-BPF.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

---

new in v5
---
drivers/hid/hid-core.c | 4 +++-
include/linux/hid.h | 2 ++
2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index db925794fbe6..e78f35cfd2d1 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2735,10 +2735,12 @@ int hid_add_device(struct hid_device *hdev)
hid_warn(hdev, "bad device descriptor (%d)\n", ret);
}

+ hdev->id = atomic_inc_return(&id);
+
/* XXX hack, any other cleaner solution after the driver core
* is converted to allow more than 20 bytes as the device name? */
dev_set_name(&hdev->dev, "%04X:%04X:%04X.%04X", hdev->bus,
- hdev->vendor, hdev->product, atomic_inc_return(&id));
+ hdev->vendor, hdev->product, hdev->id);

hid_debug_register(hdev, dev_name(&hdev->dev));
ret = device_add(&hdev->dev);
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 4363a63b9775..a43dd17bc78f 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -658,6 +658,8 @@ struct hid_device { /* device report descriptor */
struct list_head debug_list;
spinlock_t debug_list_lock;
wait_queue_head_t debug_wait;
+
+ unsigned int id; /* system unique id */
};

#define to_hid_device(pdev) \
--
2.36.1