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authorLinus Torvalds <torvalds@linux-foundation.org>2014-06-13 01:27:40 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-13 01:27:40 +0400
commitf9da455b93f6ba076935b4ef4589f61e529ae046 (patch)
tree3c4e69ce1ba1d6bf65915b97a76ca2172105b278 /Documentation/networking/can.txt
parent0e04c641b199435f3779454055f6a7de258ecdfc (diff)
parente5eca6d41f53db48edd8cf88a3f59d2c30227f8e (diff)
downloadlinux-f9da455b93f6ba076935b4ef4589f61e529ae046.tar.xz
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
Pull networking updates from David Miller: 1) Seccomp BPF filters can now be JIT'd, from Alexei Starovoitov. 2) Multiqueue support in xen-netback and xen-netfront, from Andrew J Benniston. 3) Allow tweaking of aggregation settings in cdc_ncm driver, from Bjørn Mork. 4) BPF now has a "random" opcode, from Chema Gonzalez. 5) Add more BPF documentation and improve test framework, from Daniel Borkmann. 6) Support TCP fastopen over ipv6, from Daniel Lee. 7) Add software TSO helper functions and use them to support software TSO in mvneta and mv643xx_eth drivers. From Ezequiel Garcia. 8) Support software TSO in fec driver too, from Nimrod Andy. 9) Add Broadcom SYSTEMPORT driver, from Florian Fainelli. 10) Handle broadcasts more gracefully over macvlan when there are large numbers of interfaces configured, from Herbert Xu. 11) Allow more control over fwmark used for non-socket based responses, from Lorenzo Colitti. 12) Do TCP congestion window limiting based upon measurements, from Neal Cardwell. 13) Support busy polling in SCTP, from Neal Horman. 14) Allow RSS key to be configured via ethtool, from Venkata Duvvuru. 15) Bridge promisc mode handling improvements from Vlad Yasevich. 16) Don't use inetpeer entries to implement ID generation any more, it performs poorly, from Eric Dumazet. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1522 commits) rtnetlink: fix userspace API breakage for iproute2 < v3.9.0 tcp: fixing TLP's FIN recovery net: fec: Add software TSO support net: fec: Add Scatter/gather support net: fec: Increase buffer descriptor entry number net: fec: Factorize feature setting net: fec: Enable IP header hardware checksum net: fec: Factorize the .xmit transmit function bridge: fix compile error when compiling without IPv6 support bridge: fix smatch warning / potential null pointer dereference via-rhine: fix full-duplex with autoneg disable bnx2x: Enlarge the dorq threshold for VFs bnx2x: Check for UNDI in uncommon branch bnx2x: Fix 1G-baseT link bnx2x: Fix link for KR with swapped polarity lane sctp: Fix sk_ack_backlog wrap-around problem net/core: Add VF link state control policy net/fsl: xgmac_mdio is dependent on OF_MDIO net/fsl: Make xgmac_mdio read error message useful net_sched: drr: warn when qdisc is not work conserving ...
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diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt
index 4f7ae5261364..2236d6dcb7da 100644
--- a/Documentation/networking/can.txt
+++ b/Documentation/networking/can.txt
@@ -469,6 +469,41 @@ solution for a couple of reasons:
having this 'send only' use-case we may remove the receive list in the
Kernel to save a little (really a very little!) CPU usage.
+ 4.1.1.1 CAN filter usage optimisation
+
+ The CAN filters are processed in per-device filter lists at CAN frame
+ reception time. To reduce the number of checks that need to be performed
+ while walking through the filter lists the CAN core provides an optimized
+ filter handling when the filter subscription focusses on a single CAN ID.
+
+ For the possible 2048 SFF CAN identifiers the identifier is used as an index
+ to access the corresponding subscription list without any further checks.
+ For the 2^29 possible EFF CAN identifiers a 10 bit XOR folding is used as
+ hash function to retrieve the EFF table index.
+
+ To benefit from the optimized filters for single CAN identifiers the
+ CAN_SFF_MASK or CAN_EFF_MASK have to be set into can_filter.mask together
+ with set CAN_EFF_FLAG and CAN_RTR_FLAG bits. A set CAN_EFF_FLAG bit in the
+ can_filter.mask makes clear that it matters whether a SFF or EFF CAN ID is
+ subscribed. E.g. in the example from above
+
+ rfilter[0].can_id = 0x123;
+ rfilter[0].can_mask = CAN_SFF_MASK;
+
+ both SFF frames with CAN ID 0x123 and EFF frames with 0xXXXXX123 can pass.
+
+ To filter for only 0x123 (SFF) and 0x12345678 (EFF) CAN identifiers the
+ filter has to be defined in this way to benefit from the optimized filters:
+
+ struct can_filter rfilter[2];
+
+ rfilter[0].can_id = 0x123;
+ rfilter[0].can_mask = (CAN_EFF_FLAG | CAN_RTR_FLAG | CAN_SFF_MASK);
+ rfilter[1].can_id = 0x12345678 | CAN_EFF_FLAG;
+ rfilter[1].can_mask = (CAN_EFF_FLAG | CAN_RTR_FLAG | CAN_EFF_MASK);
+
+ setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, &rfilter, sizeof(rfilter));
+
4.1.2 RAW socket option CAN_RAW_ERR_FILTER
As described in chapter 3.4 the CAN interface driver can generate so