3557f08577
[ Upstream commit 381419fa720060ba48b7bbc483be787d5b1dca6f ] The SCSI core does not like to have devices or hosts unregistered while error recovery is in progress. Trying to do so can lead to self-deadlock: Part of the removal code tries to obtain a lock already held by the error handler. This can cause problems for the usb-storage and uas drivers, because their error handler routines perform a USB reset, and if the reset fails then the USB core automatically goes on to unbind all drivers from the device's interfaces -- all while still in the context of the SCSI error handler. As it turns out, practically all the scenarios leading to a USB reset failure end up causing a device disconnect (the main error pathway in usb_reset_and_verify_device(), at the end of the routine, calls hub_port_logical_disconnect() before returning). As a result, the hub_wq thread will soon become aware of the problem and will unbind all the device's drivers in its own context, not in the error-handler's context. This means that usb_reset_device() does not need to call usb_unbind_and_rebind_marked_interfaces() in cases where usb_reset_and_verify_device() has returned an error, because hub_wq will take care of everything anyway. This particular problem was observed in somewhat artificial circumstances, by using usbfs to tell a hub to power-down a port connected to a USB-3 mass storage device using the UAS protocol. With the port turned off, the currently executing command timed out and the error handler started running. The USB reset naturally failed, because the hub port was off, and the error handler deadlocked as described above. Not carrying out the call to usb_unbind_and_rebind_marked_interfaces() fixes this issue. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Reported-by: Kento Kobayashi <Kento.A.Kobayashi@sony.com> Tested-by: Kento Kobayashi <Kento.A.Kobayashi@sony.com> CC: Bart Van Assche <bvanassche@acm.org> CC: Martin K. Petersen <martin.petersen@oracle.com> CC: Jacky Cao <Jacky.Cao@sony.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> |
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| atm | ||
| c67x00 | ||
| chipidea | ||
| class | ||
| common | ||
| core | ||
| dwc2 | ||
| dwc3 | ||
| early | ||
| gadget | ||
| host | ||
| image | ||
| isp1760 | ||
| misc | ||
| mon | ||
| musb | ||
| phy | ||
| renesas_usbhs | ||
| serial | ||
| storage | ||
| 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.