diff options
| author | Peter Hurley <peter@hurleysoftware.com> | 2014-02-09 20:59:24 -0500 |
|---|---|---|
| committer | Marcel Holtmann <marcel@holtmann.org> | 2014-02-14 13:39:32 -0800 |
| commit | 8981be9b2fe5553af35a43865d9ab4271c3aa2e2 (patch) | |
| tree | 717062972b1186decc17184b29b9e7ecce80cde3 /net/bluetooth/rfcomm | |
| parent | b16b4351313fb89ccb4c227d432d16aa32ffec72 (diff) | |
Bluetooth: Fix write_room() calculation
The skb truesize of a 12-byte payload with a 10-byte head/tail
reserve is 768 bytes. Consequently, even with 40 tx_credits, at
most 6 packets could be queued at any one time:
40 tx_credits * 127-byte mtu < 768-byte truesize * 7
This error could also cause the tx queue to apparently stall if
credit flow control is disabled (where tx_credits is fixed at 5),
or if the receiver only granted a limited number of tx credits
(eg., less than 7).
Instead, track the outstanding number of queued packets not yet sent
in wmem_alloc and allow for a maximum of 40 queued packets. Report
the space avail for a single write() as the mtu * number of packets
left before reaching the maximum.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Tested-By: Alexander Holler <holler@ahsoftware.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Diffstat (limited to 'net/bluetooth/rfcomm')
| -rw-r--r-- | net/bluetooth/rfcomm/tty.c | 14 |
1 files changed, 5 insertions, 9 deletions
diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c index 3f44195c04ad..403ec09f480a 100644 --- a/net/bluetooth/rfcomm/tty.c +++ b/net/bluetooth/rfcomm/tty.c @@ -352,20 +352,16 @@ static inline unsigned int rfcomm_room(struct rfcomm_dev *dev) { struct rfcomm_dlc *dlc = dev->dlc; - /* The limit is bogus; the number of packets which can - * currently be sent by the krfcommd thread has no relevance - * to the number of packets which can be queued on the dlc's - * tx queue. - */ - int limit = dlc->mtu * (dlc->tx_credits?:1); + /* Limit the outstanding number of packets not yet sent to 40 */ + int pending = 40 - atomic_read(&dev->wmem_alloc); - return max(0, limit - atomic_read(&dev->wmem_alloc)); + return max(0, pending) * dlc->mtu; } static void rfcomm_wfree(struct sk_buff *skb) { struct rfcomm_dev *dev = (void *) skb->sk; - atomic_sub(skb->truesize, &dev->wmem_alloc); + atomic_dec(&dev->wmem_alloc); if (test_bit(RFCOMM_TTY_ATTACHED, &dev->flags)) tty_port_tty_wakeup(&dev->port); tty_port_put(&dev->port); @@ -374,7 +370,7 @@ static void rfcomm_wfree(struct sk_buff *skb) static void rfcomm_set_owner_w(struct sk_buff *skb, struct rfcomm_dev *dev) { tty_port_get(&dev->port); - atomic_add(skb->truesize, &dev->wmem_alloc); + atomic_inc(&dev->wmem_alloc); skb->sk = (void *) dev; skb->destructor = rfcomm_wfree; } |