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| author | Ray Chi <raychi@google.com> | 2022-11-07 15:27:54 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-11-08 16:50:21 +0100 |
| commit | 430d57f53eb1cdbf9ba9bbd397317912b3cd2de5 (patch) | |
| tree | d099fea6ebe65a15b293b203ee8461c4ab6bbeec /Documentation/ABI/testing/sysfs-bus-usb | |
| parent | 04914233561377fc0369b984c9d19ec1b6ce2845 (diff) | |
| download | lwn-430d57f53eb1cdbf9ba9bbd397317912b3cd2de5.tar.gz lwn-430d57f53eb1cdbf9ba9bbd397317912b3cd2de5.zip | |
usb: core: stop USB enumeration if too many retries
When a broken USB accessory connects to a USB host, usbcore might
keep doing enumeration retries. If the host has a watchdog mechanism,
the kernel panic will happen on the host.
This patch provides an attribute early_stop to limit the numbers of retries
for each port of a hub. If a port was marked with early_stop attribute,
unsuccessful connection attempts will fail quickly. In addition, if an
early_stop port has failed to initialize, it will ignore all future
connection events until early_stop attribute is clear.
Signed-off-by: Ray Chi <raychi@google.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20221107072754.3336357-1-raychi@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/ABI/testing/sysfs-bus-usb')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-usb | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb index 568103d3376e..545c2dd97ed0 100644 --- a/Documentation/ABI/testing/sysfs-bus-usb +++ b/Documentation/ABI/testing/sysfs-bus-usb @@ -264,6 +264,17 @@ Description: attached to the port will not be detected, initialized, or enumerated. +What: /sys/bus/usb/devices/.../<hub_interface>/port<X>/early_stop +Date: Sep 2022 +Contact: Ray Chi <raychi@google.com> +Description: + Some USB hosts have some watchdog mechanisms so that the device + may enter ramdump if it takes a long time during port initialization. + This attribute allows each port just has two attempts so that the + port initialization will be failed quickly. In addition, if a port + which is marked with early_stop has failed to initialize, it will ignore + all future connections until this attribute is clear. + What: /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout Date: May 2013 Contact: Mathias Nyman <mathias.nyman@linux.intel.com> |