Return-Path: From: Peter Hurley To: Marcel Holtmann Cc: Gustavo Padovan , Johan Hedberg , Gianluca Anzolin , Alexander Holler , Andrey Vihrov , Sander Eikelenboom , linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Hurley Subject: [PATCH 23/24] Bluetooth: Refactor write_room() calculation Date: Sun, 9 Feb 2014 20:59:23 -0500 Message-Id: <1391997564-1805-24-git-send-email-peter@hurleysoftware.com> In-Reply-To: <1391997564-1805-1-git-send-email-peter@hurleysoftware.com> References: <1391997564-1805-1-git-send-email-peter@hurleysoftware.com> List-ID: Compute the amount of space available for a single write() within rfcomm_room(); clamp to 0 for negative values. Note this patch does not change the result of the computation. Report the amount of room returned in the debug printk. Signed-off-by: Peter Hurley --- net/bluetooth/rfcomm/tty.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-) diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c index af775f3..3f44195 100644 --- a/net/bluetooth/rfcomm/tty.c +++ b/net/bluetooth/rfcomm/tty.c @@ -348,11 +348,18 @@ static int rfcomm_dev_add(struct rfcomm_dev_req *req, struct rfcomm_dlc *dlc) } /* ---- Send buffer ---- */ -static inline unsigned int rfcomm_room(struct rfcomm_dlc *dlc) +static inline unsigned int rfcomm_room(struct rfcomm_dev *dev) { - /* We can't let it be zero, because we don't get a callback - when tx_credits becomes nonzero, hence we'd never wake up */ - return dlc->mtu * (dlc->tx_credits?:1); + 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); + + return max(0, limit - atomic_read(&dev->wmem_alloc)); } static void rfcomm_wfree(struct sk_buff *skb) @@ -809,16 +816,12 @@ static int rfcomm_tty_write(struct tty_struct *tty, const unsigned char *buf, in static int rfcomm_tty_write_room(struct tty_struct *tty) { struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data; - int room; + int room = 0; - BT_DBG("tty %p", tty); - - if (!dev || !dev->dlc) - return 0; + if (dev && dev->dlc) + room = rfcomm_room(dev); - room = rfcomm_room(dev->dlc) - atomic_read(&dev->wmem_alloc); - if (room < 0) - room = 0; + BT_DBG("tty %p room %d", tty, room); return room; } -- 1.8.1.2