ioctl(USB_RAW_IOCTL_EP_READ): Cannot send after transport endpoint shutdown when changing altinterface about usb-proxy

[AristoChen]

Hi,

Thanks for reporting the issue!

could you please provide the output of this command lsusb -v -d 045e:02ea?

[RandomOnlineName]

Bus 001 Device 010: ID 045e:02ea Microsoft Corp. Xbox One S Controller
Couldn't open device, some information will be missing
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 255 Vendor Specific Class
bDeviceSubClass 71
bDeviceProtocol 208
bMaxPacketSize0 64
idVendor 0x045e Microsoft Corp.
idProduct 0x02ea Xbox One S Controller
bcdDevice 5.0d
iManufacturer 1 Microsoft
iProduct 2 Controller
iSerial 3 3033363030313331323636383530
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 0x0077
bNumInterfaces 3
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xa0
(Bus Powered)
Remote Wakeup
MaxPower 500mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 2
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 71
bInterfaceProtocol 208
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 4
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 4
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 1
bNumEndpoints 2
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 71
bInterfaceProtocol 208
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 4
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 2
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 71
bInterfaceProtocol 208
iInterface 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 1
bNumEndpoints 2
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 71
bInterfaceProtocol 208
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x03 EP 3 OUT
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x00e4 1x 228 bytes
bInterval 1
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x83 EP 3 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 71
bInterfaceProtocol 208
iInterface 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 1
bNumEndpoints 2
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 71
bInterfaceProtocol 208
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x04 EP 4 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x84 EP 4 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0

[AristoChen]

Hi @RandomOnlineName ,

Thanks for providing the info, could you please also provide the output of uname -a? and what is the OS that you were proxying to? is it Linux or Windows?

And I got a Xbox controller to test today, I do encounter similiar issue, and please try to switch to commit ID 6aecd455b2ef3d6734ab92105ca00c01464d4030 to test again

# in usb-proxy directory
$ git reset --hard 6aecd455b2ef3d6734ab92105ca00c01464d4030
$ make -j$(nproc)

with commit ID 6aecd455b2ef3d6734ab92105ca00c01464d4030, the xbox controller seems to be able to send some data and usb-proxy won't die, but does't look like it's working totally fine, I will spend more time on this issue when I have time, thanks!

[RandomOnlineName]

uname -a outputs "Linux rasberrypi 5.15.89v7lAlex+ #3 SMP Tue Mar 21 18:08:19 GMT 2023 armv7l GNU/Linux"
I reset to top 6aecd45 but the same issue persists
The error above occurs when proxying to a windows laptop but another error happens when using both a linux laptop and a chromebook
"ioctl(USB_RAW_IOCTL_RUN): No such device" just after "Setup USB config successfully"

[xairy]

I think the problem is that the please_stop_eps logic doesn't really work with Raw Gadget. usb_raw_ep_read blocks until it receives some data. We need to kill the thread that calls usb_raw_ep_read when switching altsetting/interface (and also on a USB reset event, although Raw Gadget has no capability of reporting that yet). Otherwise, usb_raw_ep_read will fail with -ESHUTDOWN once usb_raw_ep_disable is called. It's actually surprising that proxy worked for some altsetting/interface-switching devices at all.

[xairy]

It's also possible that we need this Raw Gadget patch xairy/raw-gadget@60042be to avoid disabling the Raw Gadget device if the emulation code accidentally does an endpoint operation on a disabled endpoint.

[AristoChen]

Hi @xairy ,

Thanks for helping out on this issue!

I was awared that the please_stop_eps logic is not fully compatible with Raw Gadget previously, and I remember that there is a To-Do to make Raw Gadget operate in non_blocking mode, and I assume it would be working with the current please_stop_eps logic better.

I didn't try to implement the mechanism to kill the thread that calls usb_raw_ep_read when switching altsetting/interface previously, because IMHO I think it is a workaround and implementing non_blocking mode may be a better solution for this issue. I am 100% willing to try to implement it in Raw Gadget, but unfortunately I am not a kernel expert, so I don't know where and how to start :(

I will try that patch and update the result here when I have time. Thanks again for the help!

[xairy]

I don't think implementing the non-blocking mode will make that much of a difference: we will still need some way to wait for the transfer to complete and will still need a way to interrupt this waiting.

Using a signal to interrupt a blocking syscall is not that unusual of an approach. Technically, we don't even need to kill the thread. We can use any signal and add a no-op handler for it. The important part is that sending a signal will interrupt the usb_raw_ep_read call and make it return to userspace. And then the rest of the please_stop_eps logic should just work.

To make this work, we also need this patch btw xairy/raw-gadget@98f9a64, besides the one I linked above. If all this proves to work, I will send these patches upstream.

[AristoChen]

Hi @xairy , I see, thanks for the explanation!

Hi @RandomOnlineName , I might need your help, I think my Xbox controller behaves differently by comparing your log and my log, I never received the USB control request to change interface/altsetting, so please apply the patches mentioned above for Raw Gadget and apply the following for usb-proxy

diff --git a/proxy.cpp b/proxy.cpp
index e3dbd57..e139e3a 100644
--- a/proxy.cpp
+++ b/proxy.cpp
@@ -291,8 +291,15 @@ void terminate_eps(int fd, int config, int interface, int altsetting) {
        for (int i = 0; i < alt->interface.bNumEndpoints; i++) {
                struct raw_gadget_endpoint *ep = &alt->endpoints[i];
 
-               if (ep->thread_read && pthread_join(ep->thread_read, NULL)) {
-                       fprintf(stderr, "Error join thread_read\n");
+               if (ep->thread_read) {
+                       if (ep->thread_info.dir == "out") {
+                               pthread_kill(ep->thread_read, SIGINT);
+                               printf("Sent SIGINT to thread_read for EP%02x\n",
+                                               ep->thread_info.endpoint.bEndpointAddress);
+                       }
+                       if (pthread_join(ep->thread_read, NULL)) {
+                               fprintf(stderr, "Error join thread_read\n");
+                       }
                }
                if (ep->thread_write && pthread_join(ep->thread_write, NULL)) {
                        fprintf(stderr, "Error join thread_write\n");

I don't have a proper USB device to test this logic, hopefully it works, feel free to let me know if it doesn't, thanks

[RandomOnlineName]

I will test this when I get back to my computer. Thank you for the help.

[RandomOnlineName]

It causes an "ioctl(USB_RAW_IOCTL_READ): Interrupted system call" error with the same log otherwise

[xairy]

@RandomOnlineName I think you need to add a no-op handler for SIGINT.

[xairy]

I tested out the approach I suggested: xairy/raw-gadget@0732f53, it works. I used it for handling the reset event, but it should work the same for switching altsetting/interface.

[xairy]

A cleaner solution via pthread_cancel: xairy/raw-gadget@f380fc5.

On a side note, I found this article very useful to learn about pthread cancellation.

[xairy]

Looked through usb-proxy code: #9 (comment) + pthread_cancel instead of pthread_kill should work, but there's a caveat: if the endpoint thread gets cancelled with data_mutex locked, this will result in a dead lock. Also if it gets cancelled while data is allocated, there will be a memory leak.

However, what I just realized is that we don't need to interrupt the ioctl via a signal. We can just disable the endpoint (before attempting to join the thread) and the blocking ioctl should exit with -ESHUTDOWN (or with -EBUSY if the endpoint is disabled before the ioctl is called).

@RandomOnlineName, could you check if this patch works for you (with Raw Gadget patches from its dev branch)?

Actually, scratch that: usb_ep_disable will fail due to waiting for urb completion.

[xairy]

Looks like interrupting blocked threads will not fix proxying the device. Something else is wrong: I don't think the host is supposed to send those USB_REQ_SET_INTERFACE requests at all. They make no sense: each interface already has the altsetting 0 set. xairy@b21a3a1 surfaces the issue.

[xairy]

Added support for reset handling: https://github.com/xairy/usb-proxy/tree/reset. Together with ignoring meaningless SET_INTERFACE requests, I can proxy an Xbox controller (connected to Windows; Linux works as is).

Requires Raw Gadget patches from dev branch. I've sent them upstream, but it's going to take some time before they are merged. I'll hold off sending a PR before the patches are at least in one of the USB trees.

[RandomOnlineName]

I have tried https://github.com/xairy/usb-proxy/tree/reset and https://github.com/xairy/raw-gadget/tree/dev but get

event: disconnect
usb_raw_ep_read(): Cannot send after transport endpoint shutdown
usb_raw_ep_write(): Cannot send after transport endpoint shutdown

Could there be something different about our devices like kernel version or something else?

[xairy]

Ah, I think this is that bug in dwc2 that it reports a disconnect instead of a reset.

Please try this patch:

diff --git a/proxy.cpp b/proxy.cpp
index 28d288e..ec09b82 100644
--- a/proxy.cpp
+++ b/proxy.cpp
@@ -354,7 +354,7 @@ void ep0_loop(int fd) {
                        return;
                }
 
-               if (event.inner.type == USB_RAW_EVENT_RESET) {
+               if (event.inner.type == USB_RAW_EVENT_RESET || event.inner.type == USB_RAW_EVENT_DISCONNECT) {
                        printf("Resetting device\n");
                        // Normally, we would need to stop endpoint threads first and only then
                        // reset the device. However, libusb does not allow interrupting queued

If it still fails, please upload the full log somewhere and share.

[xairy]

Checked with my R Pi 4, we also need something like this:

diff --git a/proxy.cpp b/proxy.cpp
index 2ae255a..6474545 100644
--- a/proxy.cpp
+++ b/proxy.cpp
@@ -129,7 +129,7 @@ void *ep_loop_write(void *arg) {
 
                if (ep.bEndpointAddress & USB_DIR_IN) {
                        int rv = usb_raw_ep_write(fd, (struct usb_raw_ep_io *)&io);
-                       if (rv < 0 && please_stop_eps) {
+                       if (rv < 0) {
                                printf("EP%x(%s_%s): thread interrupted\n", ep.bEndpointAddress,
                                        transfer_type.c_str(), dir.c_str());
                                break;
@@ -218,7 +218,7 @@ void *ep_loop_read(void *arg) {
                        io.inner.length = sizeof(io.data);
 
                        int rv = usb_raw_ep_read(fd, (struct usb_raw_ep_io *)&io);
-                       if (rv < 0 && please_stop_eps) {
+                       if (rv < 0) {
                                printf("EP%x(%s_%s): thread interrupted\n", ep.bEndpointAddress,
                                        transfer_type.c_str(), dir.c_str());
                                break;

And then it works.

I'll think about how to implement this more cleanly.

[xairy]

Raw Gadget patches are now in usb-next, so I includes the changes into the master branch of Raw Gadget.

Waiting for #10 to be reviewed, and then will send another PR with reset handling that fixes this issue (https://github.com/xairy/usb-proxy/commits/reset).