Re: [PATCH 1/2] Bluetooth: Fix early return from l2cap_chan_del

[Mat Martineau <mathewm@codeaurora.org>]

Hi Marcel -

On Thu, 17 May 2012, Marcel Holtmann wrote:

> Hi Mat,
>
>> This fixes a regression from commit
>> 2ead70b8390d199ca04cd35311b51f5f3676079e that is present in all
>> kernels starting at v3.0.
>>
>> When L2CAP information was moved to struct l2cap_chan, a check was
>> added to l2cap_chan_del to avoid certain cleanup operations when ERTM
>> or streaming mode had not yet been initialized.  The logic in the
>> check did not take in to account that chan->conf_state is set to 0 in
>> l2cap_chan_ready, so l2cap_chan_del failed to cancel timers and leaked
>> memory any time the ERTM queues or lists were not empty.
>>
>> This change makes sure that l2cap_chan_del only returns early if
>> ERTM initialization was not performed.
>>
>> Signed-off-by: Mat Martineau <mathewm@codeaurora.org>
>> ---
>>  include/net/bluetooth/l2cap.h |    1 +
>>  net/bluetooth/l2cap_core.c    |    4 ++--
>>  2 files changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
>> index 1c7d1cd..452fcc4 100644
>> --- a/include/net/bluetooth/l2cap.h
>> +++ b/include/net/bluetooth/l2cap.h
>> @@ -597,6 +597,7 @@ enum {
>>  	CONF_EWS_RECV,
>>  	CONF_LOC_CONF_PEND,
>>  	CONF_REM_CONF_PEND,
>> +	CONF_NOT_COMPLETE,
>>  };
>>
>>  #define L2CAP_CONF_MAX_CONF_REQ 2
>> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
>> index 24f144b..36edd42 100644
>> --- a/net/bluetooth/l2cap_core.c
>> +++ b/net/bluetooth/l2cap_core.c
>> @@ -391,6 +391,7 @@ struct l2cap_chan *l2cap_chan_create(void)
>>  	chan->state = BT_OPEN;
>>
>>  	atomic_set(&chan->refcnt, 1);
>> +	set_bit(CONF_NOT_COMPLETE, &chan->conf_state);
>>
>>  	BT_DBG("chan %p", chan);
>>
>> @@ -509,8 +510,7 @@ static void l2cap_chan_del(struct l2cap_chan *chan, int err)
>>
>>  	release_sock(sk);
>>
>> -	if (!(test_bit(CONF_OUTPUT_DONE, &chan->conf_state) &&
>> -			test_bit(CONF_INPUT_DONE, &chan->conf_state)))
>> +	if (test_bit(CONF_NOT_COMPLETE, &chan->conf_state))
>>  		return;
>
> explain to me how this works? We never clear that bit.

Line 926 in l2cap_chan_ready (called after configuration is done) is 
existing code that I didn't change:

         chan->conf_state = 0;

So all bits are cleared at once, including CONF_NOT_COMPLETE.

--
Mat Martineau
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum