ab219221a5
The dummy-hcd driver calls the gadget driver's disconnect callback under the wrong conditions. It should invoke the callback when Vbus power is turned off, but instead it does so when the D+ pullup is turned off. This can cause a deadlock in the composite core when a gadget driver is unregistered: [ 88.361471] ============================================ [ 88.362014] WARNING: possible recursive locking detected [ 88.362580] 4.14.0-rc2+ #9 Not tainted [ 88.363010] -------------------------------------------- [ 88.363561] v4l_id/526 is trying to acquire lock: [ 88.364062] (&(&cdev->lock)->rlock){....}, at: [<ffffffffa0547e03>] composite_disconnect+0x43/0x100 [libcomposite] [ 88.365051] [ 88.365051] but task is already holding lock: [ 88.365826] (&(&cdev->lock)->rlock){....}, at: [<ffffffffa0547b09>] usb_function_deactivate+0x29/0x80 [libcomposite] [ 88.366858] [ 88.366858] other info that might help us debug this: [ 88.368301] Possible unsafe locking scenario: [ 88.368301] [ 88.369304] CPU0 [ 88.369701] ---- [ 88.370101] lock(&(&cdev->lock)->rlock); [ 88.370623] lock(&(&cdev->lock)->rlock); [ 88.371145] [ 88.371145] *** DEADLOCK *** [ 88.371145] [ 88.372211] May be due to missing lock nesting notation [ 88.372211] [ 88.373191] 2 locks held by v4l_id/526: [ 88.373715] #0: (&(&cdev->lock)->rlock){....}, at: [<ffffffffa0547b09>] usb_function_deactivate+0x29/0x80 [libcomposite] [ 88.374814] #1: (&(&dum_hcd->dum->lock)->rlock){....}, at: [<ffffffffa05bd48d>] dummy_pullup+0x7d/0xf0 [dummy_hcd] [ 88.376289] [ 88.376289] stack backtrace: [ 88.377726] CPU: 0 PID: 526 Comm: v4l_id Not tainted 4.14.0-rc2+ #9 [ 88.378557] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 88.379504] Call Trace: [ 88.380019] dump_stack+0x86/0xc7 [ 88.380605] __lock_acquire+0x841/0x1120 [ 88.381252] lock_acquire+0xd5/0x1c0 [ 88.381865] ? composite_disconnect+0x43/0x100 [libcomposite] [ 88.382668] _raw_spin_lock_irqsave+0x40/0x54 [ 88.383357] ? composite_disconnect+0x43/0x100 [libcomposite] [ 88.384290] composite_disconnect+0x43/0x100 [libcomposite] [ 88.385490] set_link_state+0x2d4/0x3c0 [dummy_hcd] [ 88.386436] dummy_pullup+0xa7/0xf0 [dummy_hcd] [ 88.387195] usb_gadget_disconnect+0xd8/0x160 [udc_core] [ 88.387990] usb_gadget_deactivate+0xd3/0x160 [udc_core] [ 88.388793] usb_function_deactivate+0x64/0x80 [libcomposite] [ 88.389628] uvc_function_disconnect+0x1e/0x40 [usb_f_uvc] This patch changes the code to test the port-power status bit rather than the port-connect status bit when deciding whether to isue the callback. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Reported-by: David Tulloh <david@tulloh.id.au> CC: <stable@vger.kernel.org> Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com> |
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|---|---|---|
| .. | ||
| atm | ||
| c67x00 | ||
| chipidea | ||
| class | ||
| common | ||
| core | ||
| dwc2 | ||
| dwc3 | ||
| early | ||
| gadget | ||
| host | ||
| image | ||
| isp1760 | ||
| misc | ||
| mon | ||
| mtu3 | ||
| musb | ||
| phy | ||
| renesas_usbhs | ||
| serial | ||
| storage | ||
| typec | ||
| usbip | ||
| wusbcore | ||
| Kconfig | ||
| Makefile | ||
| README | ||
| usb-skeleton.c | ||
README
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.