can bcm: fix tx_setup off-by-one errors

[ Upstream commit aabdcb0b553b9c9547b1a506b34d55a764745870 ]

This patch fixes two off-by-one errors that canceled each other out.
Checking for the same condition two times in bcm_tx_timeout_tsklet() reduced
the count of frames to be sent by one. This did not show up the first time
tx_setup is invoked as an additional frame is sent due to TX_ANNONCE.
Invoking a second tx_setup on the same item led to a reduced (by 1) number of
sent frames.

Reported-by: Andre Naujoks <nautsch@gmail.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/can/bcm.c b/net/can/bcm.c
index 184a6572b67e6be824ba1ef30b122d065269a262..8838b86f2f27d1a5cda52c28f9dc3dd2188a1dda 100644 (file)
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -364,9 +364,6 @@ static void bcm_tx_timeout_tsklet(unsigned long data)
 
                        bcm_send_to_user(op, &msg_head, NULL, 0);
                }
-       }
-
-       if (op->kt_ival1.tv64 && (op->count > 0)) {
 
                /* send (next) frame */
                bcm_can_tx(op);
@@ -969,8 +966,9 @@ static int bcm_tx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
                /* spec: send can_frame when starting timer */
                op->flags |= TX_ANNOUNCE;
 
-               if (op->kt_ival1.tv64 && (op->count > 0)) {
-                       /* op->count-- is done in bcm_tx_timeout_handler */
+               /* only start timer when having more frames than sent below */
+               if (op->kt_ival1.tv64 && (op->count > 1)) {
+                       /* op->count-- is done in bcm_tx_timeout_tsklet */
                        hrtimer_start(&op->timer, op->kt_ival1,
                                      HRTIMER_MODE_REL);
                } else
@@ -978,8 +976,11 @@ static int bcm_tx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
                                      HRTIMER_MODE_REL);
        }
 
-       if (op->flags & TX_ANNOUNCE)
+       if (op->flags & TX_ANNOUNCE) {
                bcm_can_tx(op);
+               if (op->kt_ival1.tv64 && (op->count > 0))
+                       op->count--;
+       }
 
        return msg_head->nframes * CFSIZ + MHSIZ;
 }