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The hub sends hot-plug events to the host trough it's interrupt URB. The driver takes care of completing the URB and re-submitting it. Completion errors are handled in the hub_event() work, yet submission errors are ignored, rendering the device unresponsive. All further events are lost. It is fairly hard to find this issue in the wild, since you have to time the USB hot-plug event with the URB submission failure. For instance it could be the system running out of memory or some malfunction in the USB controller driver. Nevertheless, it's pretty reasonable to think it'll happen sometime. One can trigger this issue using eBPF's function override feature (see BCC's inject.py script). This patch adds a retry routine to the event of a submission error. The HUB driver will try to re-submit the URB once every second until it's successful or the HUB is disconnected. As some USB subsystems already take care of this issue, the implementation was inspired from usbhid/hid_core.c's. Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> Reviewed-by: Oliver Neukum <oneukum@suse.com> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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atm | ||
c67x00 | ||
chipidea | ||
class | ||
common | ||
core | ||
dwc2 | ||
dwc3 | ||
early | ||
gadget | ||
host | ||
image | ||
isp1760 | ||
misc | ||
mon | ||
mtu3 | ||
musb | ||
phy | ||
renesas_usbhs | ||
roles | ||
serial | ||
storage | ||
typec | ||
usbip | ||
wusbcore | ||
Kconfig | ||
Makefile | ||
README | ||
usb-skeleton.c |
To understand all the Linux-USB framework, you'll use these resources: * This source code. This is necessarily an evolving work, and includes kerneldoc that should help you get a current overview. ("make pdfdocs", and then look at "usb.pdf" for host side and "gadget.pdf" for peripheral side.) Also, Documentation/usb has more information. * The USB 2.0 specification (from www.usb.org), with supplements such as those for USB OTG and the various device classes. The USB specification has a good overview chapter, and USB peripherals conform to the widely known "Chapter 9". * Chip specifications for USB controllers. Examples include host controllers (on PCs, servers, and more); peripheral controllers (in devices with Linux firmware, like printers or cell phones); and hard-wired peripherals like Ethernet adapters. * Specifications for other protocols implemented by USB peripheral functions. Some are vendor-specific; others are vendor-neutral but just standardized outside of the www.usb.org team. Here is a list of what each subdirectory here is, and what is contained in them. core/ - This is for the core USB host code, including the usbfs files and the hub class driver ("hub_wq"). host/ - This is for USB host controller drivers. This includes UHCI, OHCI, EHCI, and others that might be used with more specialized "embedded" systems. gadget/ - This is for USB peripheral controller drivers and the various gadget drivers which talk to them. Individual USB driver directories. A new driver should be added to the first subdirectory in the list below that it fits into. image/ - This is for still image drivers, like scanners or digital cameras. ../input/ - This is for any driver that uses the input subsystem, like keyboard, mice, touchscreens, tablets, etc. ../media/ - This is for multimedia drivers, like video cameras, radios, and any other drivers that talk to the v4l subsystem. ../net/ - This is for network drivers. serial/ - This is for USB to serial drivers. storage/ - This is for USB mass-storage drivers. class/ - This is for all USB device drivers that do not fit into any of the above categories, and work for a range of USB Class specified devices. misc/ - This is for all USB device drivers that do not fit into any of the above categories.