Re: [PATCH v2] Bluetooth: Fix calling request callback more than once

[Gustavo Padovan <gustavo@padovan.org>]

Hi Johan,

* johan.hedberg@gmail.com <johan.hedberg@gmail.com> [2013-07-27 14:11:14 -0500]:

> From: Johan Hedberg <johan.hedberg@intel.com>
> 
> In certain circumstances, such as an HCI driver using __hci_cmd_sync_ev
> with HCI_EV_CMD_COMPLETE as the expected completion event there is the
> chance that hci_event_packet will call hci_req_cmd_complete twice (once
> for the explicitly looked after event and another time in the actual
> handler of cmd_complete).
> 
> In the case of __hci_cmd_sync_ev this introduces a race where the first
> call wakes up the blocking __hci_cmd_sync_ev and lets it complete.
> However, by the time that a second __hci_cmd_sync_ev call is already in
> progress the second hci_req_cmd_complete call (from the previous
> operation) will wake up the blocking function prematurely and cause it
> to fail, as witnessed by the following log:
> 
> [  639.232195] hci_rx_work: hci0 Event packet
> [  639.232201] hci_req_cmd_complete: opcode 0xfc8e status 0x00
> [  639.232205] hci_sent_cmd_data: hci0 opcode 0xfc8e
> [  639.232210] hci_req_sync_complete: hci0 result 0x00
> [  639.232220] hci_cmd_complete_evt: hci0 opcode 0xfc8e
> [  639.232225] hci_req_cmd_complete: opcode 0xfc8e status 0x00
> [  639.232228] __hci_cmd_sync_ev: hci0 end: err 0
> [  639.232234] __hci_cmd_sync_ev: hci0
> [  639.232238] hci_req_add_ev: hci0 opcode 0xfc8e plen 250
> [  639.232242] hci_prepare_cmd: skb len 253
> [  639.232246] hci_req_run: length 1
> [  639.232250] hci_sent_cmd_data: hci0 opcode 0xfc8e
> [  639.232255] hci_req_sync_complete: hci0 result 0x00
> [  639.232266] hci_cmd_work: hci0 cmd_cnt 1 cmd queued 1
> [  639.232271] __hci_cmd_sync_ev: hci0 end: err 0
> [  639.232276] Bluetooth: hci0 sending Intel patch command (0xfc8e) failed (-61)
> 
> Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
> ---
> v2: Only set complete callback to NULL if it was not already so
> 
>  net/bluetooth/hci_core.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)

Patch has been applied to bluetooth.git. Thanks.

	Gustavo