On 08/27/2013 12:28 PM, Gianluca Anzolin wrote:
When the dlc is closed, rfcomm_dev_state_change() tries to release the
port in the case it cannot get a reference to the tty. However this is
racy and not even needed.
Infact as Peter Hurley points out:
1. Only consider dlcs that are 'stolen' from a connected socket, ie.
reused. Allocated dlcs cannot have been closed prior to port
activate and so for these dlcs a tty reference will always be avail
in rfcomm_dev_state_change() -- except for the conditions covered by
#2b below.
2. If a tty was at some point previously created for this rfcomm, then
either
(a) the tty reference is still avail, so rfcomm_dev_state_change()
will perform a hangup. So nothing to do, or,
(b) the tty reference is no longer avail, and the tty_port will be
destroyed by the last tty_port_put() in rfcomm_tty_cleanup.
Again, no action required.
3. Prior to obtaining the dlc lock in rfcomm_dev_add(),
rfcomm_dev_state_change() will not 'see' a rfcomm_dev so nothing to
do here.
4. After releasing the dlc lock in rfcomm_dev_add(),
rfcomm_dev_state_change() will 'see' an incomplete rfcomm_dev if a
tty reference could not be obtained. Again, the best thing to do here
is nothing. Any future attempted open() will block on
rfcomm_dev_carrier_raised(). The unconnected device will exist until
released by ioctl(RFCOMMRELEASEDEV).
The patch removes the aforementioned code and uses the
tty_port_tty_hangup() helper to hangup the tty.
Sorry for the delay in reviewing.
Reviewed-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
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