USB: cdc-acm: fix write and suspend race
authorJohan Hovold <jhovold@gmail.com>
Mon, 26 May 2014 17:23:36 +0000 (19:23 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 27 May 2014 22:04:08 +0000 (15:04 -0700)
commit5a345c20c17d87099224a4be12e69e5bd7023dca
tree8a5c3fd60129a12f9bd33e7f98dd4135e5bbf2c8
parent90419cfcb5d9c889b10dc51363c56a4d394d670e
USB: cdc-acm: fix write and suspend race

Fix race between write() and suspend() which could lead to writes being
dropped (or I/O while suspended) if the device is runtime suspended
while a write request is being processed.

Specifically, suspend() releases the write_lock after determining the
device is idle but before incrementing the susp_count, thus leaving a
window where a concurrent write() can submit an urb.

Fixes: 11ea859d64b6 ("USB: additional power savings for cdc-acm devices
that support remote wakeup")

Cc: <stable@vger.kernel.org> # v2.6.27
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/usb/class/cdc-acm.c