[PATCH] can: add a note that RECV_OWN_MSGS frames are subject to filtering

From: Erik Flodin <erik@flodin.me>
To: unlisted-recipients:; (no To-header on input)
Cc: Erik Flodin <erik@flodin.me>,
	Oliver Hartkopp <socketcan@hartkopp.net>,
	Marc Kleine-Budde <mkl@pengutronix.de>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Jonathan Corbet <corbet@lwn.net>,
	linux-can@vger.kernel.org, netdev@vger.kernel.org,
	linux-doc@vger.kernel.org
Subject: [PATCH] can: add a note that RECV_OWN_MSGS frames are subject to filtering
Date: Tue, 20 Apr 2021 21:12:00 +0200	[thread overview]
Message-ID: <20210420191212.42753-1-erik@flodin.me> (raw)

Some parts of the documentation may lead the reader to think that the
socket's own frames are always received when CAN_RAW_RECV_OWN_MSGS is
enabled, but all frames are subject to filtering.

As explained by Marc Kleine-Budde:

On TX complete of a CAN frame it's pushed into the RX path of the
networking stack, along with the information of the originating socket.

Then the CAN frame is delivered into AF_CAN, where it is passed on to
all registered receivers depending on filters. One receiver is the
sending socket in CAN_RAW. Then in CAN_RAW the it is checked if the
sending socket has RECV_OWN_MSGS enabled.

Signed-off-by: Erik Flodin <erik@flodin.me>
---
 Documentation/networking/can.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/networking/can.rst b/Documentation/networking/can.rst
index f8dae662e454..f34cb0e4460e 100644
--- a/Documentation/networking/can.rst
+++ b/Documentation/networking/can.rst
@@ -608,6 +608,8 @@ demand:
     setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS,
                &recv_own_msgs, sizeof(recv_own_msgs));
 
+Note that reception of a socket's own CAN frames are subject to the same
+filtering as other CAN frames (see :ref:`socketcan-rawfilter`).
 
 .. _socketcan-rawfd:
 
-- 
2.31.0

