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can: fix multiple delivery of a single CAN frame for overlapping CAN filters 

The CAN_RAW socket can set multiple CAN identifier specific filters that lead
to multiple filters in the af_can.c filter processing. These filters are
indenpendent from each other which leads to logical OR'ed filters when applied.

This patch makes sure that every CAN frame which is filtered for a specific
socket is only delivered once to the user space. This is independent from the
number of matching CAN filters of this socket.

As the raw_rcv() function is executed from NET_RX softirq the introduced
variables are implemented as per-CPU variables to avoid extensive locking at
CAN frame reception time.

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Oliver Hartkopp 2015-04-01 07:50:28 +02:00 committed by Marc Kleine-Budde
parent a0bc163a7c
commit 514ac99c64
1 changed files with 21 additions and 0 deletions
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21
net/can/raw.c
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@ -74,6 +74,11 @@ MODULE_ALIAS("can-proto-1");
* storing the single filter in dfilter, to avoid using dynamic memory.
*/
struct uniqframe {
ktime_t tstamp;
const struct sk_buff *skb;
};
struct raw_sock {
struct sock sk;
int bound;
@ -86,6 +91,7 @@ struct raw_sock {
struct can_filter dfilter; /* default/single filter */
struct can_filter *filter; /* pointer to filter(s) */
can_err_mask_t err_mask;
struct uniqframe __percpu *uniq;
};
/*
@ -123,6 +129,15 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
if (!ro->fd_frames && oskb->len != CAN_MTU)
return;
/* eliminate multiple filter matches for the same skb */
if (this_cpu_ptr(ro->uniq)->skb == oskb &&
ktime_equal(this_cpu_ptr(ro->uniq)->tstamp, oskb->tstamp)) {
return;
} else {
this_cpu_ptr(ro->uniq)->skb = oskb;
this_cpu_ptr(ro->uniq)->tstamp = oskb->tstamp;
}
/* clone the given skb to be able to enqueue it into the rcv queue */
skb = skb_clone(oskb, GFP_ATOMIC);
if (!skb)
@ -297,6 +312,11 @@ static int raw_init(struct sock *sk)
ro->recv_own_msgs = 0;
ro->fd_frames = 0;
/* alloc_percpu provides zero'ed memory */
ro->uniq = alloc_percpu(struct uniqframe);
if (unlikely(!ro->uniq))
return -ENOMEM;
/* set notifier */
ro->notifier.notifier_call = raw_notifier;
@ -339,6 +359,7 @@ static int raw_release(struct socket *sock)
ro->ifindex = 0;
ro->bound = 0;
ro->count = 0;
free_percpu(ro->uniq);
sock_orphan(sk);
sock->sk = NULL;