Re: [PATCH] usbip: tools: Add usbip host driver availability check
From: Shuah Khan
Date: Mon Mar 23 2026 - 15:48:01 EST
On 3/11/26 20:17, Zongmin Zhou wrote:
On 2026/3/11 06:28, Shuah Khan wrote:
On 3/3/26 01:17, Zongmin Zhou wrote:Actually, refresh_exported_devices() does not return an error
From: Zongmin Zhou <zhouzongmin@xxxxxxxxxx>
Currently, usbip_generic_driver_open() doesn't verify that the required
kernel module (usbip-host or usbip-vudc) is actually loaded.
The function returns success even when no driver is present,
leading to usbipd daemon run success without driver loaded.
Doesn't usbip_generic_driver_open() try to refresh exported
device list and fail? It returns error if it can't find fetch
them.
usbipd starts and the when usbip_host is loaded it works correctly.
Doesn't it?
when the driver is not loaded,it consistently returns 0.
It only results in hdriver->ndevs being set to 0 if no exportable usbip devices are found.
Consequently, if the driver is missing, usbipd will start successfully in silence,
but subsequent usbip attach operations will fail.
The lack of explicit error messages makes it difficult for users to troubleshoot the root cause.
By adding a check to verify if the driver is loaded during the usbip daemon startup,
we can prevent these silent exceptions and ensure users are alerted to
the missing kernel module before they attempt to use the service.
The reason I added the bus_type and drv_name fields is to
So add a check function to ensure usbip host driver has been loaded.
Signed-off-by: Zongmin Zhou <zhouzongmin@xxxxxxxxxx>
---
tools/usb/usbip/libsrc/usbip_device_driver.c | 2 ++
tools/usb/usbip/libsrc/usbip_host_common.c | 31 ++++++++++++++++++++
tools/usb/usbip/libsrc/usbip_host_common.h | 2 ++
tools/usb/usbip/libsrc/usbip_host_driver.c | 2 ++
4 files changed, 37 insertions(+)
diff --git a/tools/usb/usbip/libsrc/usbip_device_driver.c b/tools/usb/usbip/libsrc/usbip_device_driver.c
index 927a151fa9aa..6da000fab26d 100644
--- a/tools/usb/usbip/libsrc/usbip_device_driver.c
+++ b/tools/usb/usbip/libsrc/usbip_device_driver.c
@@ -147,6 +147,8 @@ static int usbip_device_driver_open(struct usbip_host_driver *hdriver)
struct usbip_host_driver device_driver = {
.edev_list = LIST_HEAD_INIT(device_driver.edev_list),
.udev_subsystem = "udc",
+ .bus_type = "platform",
Why are we adding this here - user-space shouldn't need to
know what kind of driver this is?
construct the specific sysfs paths required for the availability check.
Although usbip-host and usbip-vudc share the same usbip_generic_driver_open() interface ,
they operate on different bus types and have different driver names.
These fields allow the generic open function to dynamically verify
the correct driver path in sysfs based on the specific driver type being initialized.
If you prefer not to expose these in the this structure,
I'm happy to adjust further based on your suggestions.
Have you tried a simple system() e.g below:
if (system("/usr/bin/lsmod | grep usbip")) instead of adding
all of this code?
Take a look at other examples of driver checks in cpupower
check_msr_driver() for example.
thanks,
-- Shuah