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authorOliver Hartkopp <socketcan@hartkopp.net>2015-04-01 07:50:29 +0200
committerMarc Kleine-Budde <mkl@pengutronix.de>2015-04-01 11:28:22 +0200
commita5581ef4c2eac6449188862e903eb46c7233582a (patch)
treeb334b1858d3bffe49af1fb95650cb5affb7e1510 /Documentation/networking
parent514ac99c64b22d83b52dfee3b8becaa69a92bc4a (diff)
downloadkernel-a5581ef4c2eac6449188862e903eb46c7233582a.tar.gz
can: introduce new raw socket option to join the given 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 socket option joines the given CAN filters in the way that only CAN frames are passed to user space that matched *all* given CAN filters. The semantic for the applied filters is therefore changed to a logical AND. This is useful especially when the filterset is a combination of filters where the CAN_INV_FILTER flag is set in order to notch single CAN IDs or CAN ID ranges from the incoming traffic. 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>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/can.txt20
1 files changed, 18 insertions, 2 deletions
diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt
index 0a2859a8ee7e..5abad1e921ca 100644
--- a/Documentation/networking/can.txt
+++ b/Documentation/networking/can.txt
@@ -22,7 +22,8 @@ This file contains
4.1.3 RAW socket option CAN_RAW_LOOPBACK
4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
4.1.5 RAW socket option CAN_RAW_FD_FRAMES
- 4.1.6 RAW socket returned message flags
+ 4.1.6 RAW socket option CAN_RAW_JOIN_FILTERS
+ 4.1.7 RAW socket returned message flags
4.2 Broadcast Manager protocol sockets (SOCK_DGRAM)
4.2.1 Broadcast Manager operations
4.2.2 Broadcast Manager message flags
@@ -601,7 +602,22 @@ solution for a couple of reasons:
CAN FD frames by checking if the device maximum transfer unit is CANFD_MTU.
The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall.
- 4.1.6 RAW socket returned message flags
+ 4.1.6 RAW socket option CAN_RAW_JOIN_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 (see 4.1.1).
+
+ This socket option joines the given CAN filters in the way that only CAN
+ frames are passed to user space that matched *all* given CAN filters. The
+ semantic for the applied filters is therefore changed to a logical AND.
+
+ This is useful especially when the filterset is a combination of filters
+ where the CAN_INV_FILTER flag is set in order to notch single CAN IDs or
+ CAN ID ranges from the incoming traffic.
+
+ 4.1.7 RAW socket returned message flags
When using recvmsg() call, the msg->msg_flags may contain following flags: