From d253eee20195b25e298bf162a6e72f14bf4803e5 Mon Sep 17 00:00:00 2001 From: Oliver Hartkopp Date: Wed, 3 Dec 2008 15:52:35 -0800 Subject: can: Fix CAN_(EFF|RTR)_FLAG handling in can_filter Due to a wrong safety check in af_can.c it was not possible to filter for SFF frames with a specific CAN identifier without getting the same selected CAN identifier from a received EFF frame also. This fix has a minimum (but user visible) impact on the CAN filter API and therefore the CAN version is set to a new date. Indeed the 'old' API is still working as-is. But when now setting CAN_(EFF|RTR)_FLAG in can_filter.can_mask you might get less traffic than before - but still the stuff that you expected to get for your defined filter ... Thanks to Kurt Van Dijck for pointing at this issue and for the review. Signed-off-by: Oliver Hartkopp Acked-by: Kurt Van Dijck Signed-off-by: David S. Miller --- net/can/af_can.c | 63 ++++++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 48 insertions(+), 15 deletions(-) (limited to 'net/can/af_can.c') diff --git a/net/can/af_can.c b/net/can/af_can.c index 7d4d2b3c137e..d8173e50cb87 100644 --- a/net/can/af_can.c +++ b/net/can/af_can.c @@ -319,23 +319,52 @@ static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev) return n ? d : NULL; } +/** + * find_rcv_list - determine optimal filterlist inside device filter struct + * @can_id: pointer to CAN identifier of a given can_filter + * @mask: pointer to CAN mask of a given can_filter + * @d: pointer to the device filter struct + * + * Description: + * Returns the optimal filterlist to reduce the filter handling in the + * receive path. This function is called by service functions that need + * to register or unregister a can_filter in the filter lists. + * + * A filter matches in general, when + * + * & mask == can_id & mask + * + * so every bit set in the mask (even CAN_EFF_FLAG, CAN_RTR_FLAG) describe + * relevant bits for the filter. + * + * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can + * filter for error frames (CAN_ERR_FLAG bit set in mask). For error frames + * there is a special filterlist and a special rx path filter handling. + * + * Return: + * Pointer to optimal filterlist for the given can_id/mask pair. + * Constistency checked mask. + * Reduced can_id to have a preprocessed filter compare value. + */ static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask, struct dev_rcv_lists *d) { canid_t inv = *can_id & CAN_INV_FILTER; /* save flag before masking */ - /* filter error frames */ + /* filter for error frames in extra filterlist */ if (*mask & CAN_ERR_FLAG) { - /* clear CAN_ERR_FLAG in list entry */ + /* clear CAN_ERR_FLAG in filter entry */ *mask &= CAN_ERR_MASK; return &d->rx[RX_ERR]; } - /* ensure valid values in can_mask */ - if (*mask & CAN_EFF_FLAG) - *mask &= (CAN_EFF_MASK | CAN_EFF_FLAG | CAN_RTR_FLAG); - else - *mask &= (CAN_SFF_MASK | CAN_RTR_FLAG); + /* with cleared CAN_ERR_FLAG we have a simple mask/value filterpair */ + +#define CAN_EFF_RTR_FLAGS (CAN_EFF_FLAG | CAN_RTR_FLAG) + + /* ensure valid values in can_mask for 'SFF only' frame filtering */ + if ((*mask & CAN_EFF_FLAG) && !(*can_id & CAN_EFF_FLAG)) + *mask &= (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS); /* reduce condition testing at receive time */ *can_id &= *mask; @@ -348,15 +377,19 @@ static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask, if (!(*mask)) return &d->rx[RX_ALL]; - /* use extra filterset for the subscription of exactly *ONE* can_id */ - if (*can_id & CAN_EFF_FLAG) { - if (*mask == (CAN_EFF_MASK | CAN_EFF_FLAG)) { - /* RFC: a use-case for hash-tables in the future? */ - return &d->rx[RX_EFF]; + /* extra filterlists for the subscription of a single non-RTR can_id */ + if (((*mask & CAN_EFF_RTR_FLAGS) == CAN_EFF_RTR_FLAGS) + && !(*can_id & CAN_RTR_FLAG)) { + + if (*can_id & CAN_EFF_FLAG) { + if (*mask == (CAN_EFF_MASK | CAN_EFF_RTR_FLAGS)) { + /* RFC: a future use-case for hash-tables? */ + return &d->rx[RX_EFF]; + } + } else { + if (*mask == (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS)) + return &d->rx_sff[*can_id]; } - } else { - if (*mask == CAN_SFF_MASK) - return &d->rx_sff[*can_id]; } /* default: filter via can_id/can_mask */ -- cgit v1.2.3 From f706644d55f90e8306d87060168fef33804d6dd9 Mon Sep 17 00:00:00 2001 From: Oliver Hartkopp Date: Thu, 4 Dec 2008 15:01:08 -0800 Subject: can: omit received RTR frames for single ID filter lists Since commit d253eee20195b25e298bf162a6e72f14bf4803e5 the single CAN identifier filter lists handle only non-RTR CAN frames. So we need to omit the check of these filter lists when receiving RTR CAN frames. Signed-off-by: Oliver Hartkopp Signed-off-by: David S. Miller --- net/can/af_can.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'net/can/af_can.c') diff --git a/net/can/af_can.c b/net/can/af_can.c index d8173e50cb87..3dadb338addd 100644 --- a/net/can/af_can.c +++ b/net/can/af_can.c @@ -622,7 +622,10 @@ static int can_rcv_filter(struct dev_rcv_lists *d, struct sk_buff *skb) } } - /* check CAN_ID specific entries */ + /* check filterlists for single non-RTR can_ids */ + if (can_id & CAN_RTR_FLAG) + return matches; + if (can_id & CAN_EFF_FLAG) { hlist_for_each_entry_rcu(r, n, &d->rx[RX_EFF], list) { if (r->can_id == can_id) { -- cgit v1.2.3