linux-kernel - [PATCH 23/24] Bluetooth: Refactor write

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1391997564-1805-24-git-send-email-peter@hurleysoftware.com>
Date:	Sun,  9 Feb 2014 20:59:23 -0500
From:	Peter Hurley <peter@...leysoftware.com>
To:	Marcel Holtmann <marcel@...tmann.org>
Cc:	Gustavo Padovan <gustavo@...ovan.org>,
	Johan Hedberg <johan.hedberg@...il.com>,
	Gianluca Anzolin <gianluca@...tospazio.it>,
	Alexander Holler <holler@...oftware.de>,
	Andrey Vihrov <andrey.vihrov@...il.com>,
	Sander Eikelenboom <linux@...elenboom.it>,
	linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org,
	Peter Hurley <peter@...leysoftware.com>
Subject: [PATCH 23/24] Bluetooth: Refactor write_room() calculation

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 <peter@...leysoftware.com>
---
 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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/