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1c111b6c38
Current abort operation has race.
xhci_handle_command_timeout()
xhci_abort_cmd_ring()
xhci_write_64(CMD_RING_ABORT)
xhci_handshake(5s)
do {
check CMD_RING_RUNNING
udelay(1)
...
COMP_CMD_ABORT event
COMP_CMD_STOP event
xhci_handle_stopped_cmd_ring()
restart cmd_ring
CMD_RING_RUNNING become 1 again
} while ()
return -ETIMEDOUT
xhci_write_64(CMD_RING_ABORT)
/* can abort random command */
To do abort operation correctly, we have to wait both of COMP_CMD_STOP
event and negation of CMD_RING_RUNNING.
But like above, while timeout handler is waiting negation of
CMD_RING_RUNNING, event handler can restart cmd_ring. So timeout
handler never be notice negation of CMD_RING_RUNNING, and retry of
CMD_RING_ABORT can abort random command (BTW, I guess retry of
CMD_RING_ABORT was workaround of this race).
To fix this race, this moves xhci_handle_stopped_cmd_ring() to
xhci_abort_cmd_ring(). And timeout handler waits COMP_CMD_STOP event.
At this point, timeout handler is owner of cmd_ring, and safely
restart cmd_ring by using xhci_handle_stopped_cmd_ring().
[FWIW, as bonus, this way would be easily extend to add CMD_RING_PAUSE
operation]
[locks edited as patch is rebased on other locking fixes -Mathias]
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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| c67x00 | ||
| chipidea | ||
| class | ||
| common | ||
| core | ||
| dwc2 | ||
| dwc3 | ||
| early | ||
| gadget | ||
| host | ||
| image | ||
| isp1760 | ||
| misc | ||
| mon | ||
| mtu3 | ||
| 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.