USB: cdc-acm: fix broken runtime suspend

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commit 140cb81ac8 upstream.

The current ACM runtime-suspend implementation is broken in several
ways:

Firstly, it buffers only the first write request being made while
suspended -- any further writes are silently dropped.

Secondly, writes being dropped also leak write urbs, which are never
reclaimed (until the device is unbound).

Thirdly, even the single buffered write is not cleared at shutdown
(which may happen before the device is resumed), something which can
lead to another urb leak as well as a PM usage-counter leak.

Fix this by implementing a delayed-write queue using urb anchors and
making sure to discard the queue properly at shutdown.

Fixes: 11ea859d64 ("USB: additional power savings for cdc-acm devices
that support remote wakeup")

Reported-by: Xiao Jin <jin.xiao@intel.com>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Johan Hovold 2014-05-26 19:23:38 +02:00 • committed by Greg Kroah-Hartman

parent e2b5e89b63

commit e2e261103f

2 changed files with 23 additions and 11 deletions

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32

drivers/usb/class/cdc-acm.c

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2

drivers/usb/class/cdc-acm.h

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