[PATCH v4 1/7] can: netlink: allow user to turn off unsupported features

From: Vincent Mailhol
Date: Sat Aug 14 2021 - 05:19:38 EST


The sanity checks on the control modes will reject any request related
to an unsupported features, even turning it off.

Example on an interface which does not support CAN-FD:

$ ip link set can0 type can bitrate 500000 fd off
RTNETLINK answers: Operation not supported

This patch lets such command go through (but requests to turn on an
unsupported feature are, of course, still denied).

Signed-off-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
---
drivers/net/can/dev/netlink.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index 147c23d7dab7..80425636049d 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -116,7 +116,7 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
maskedflags = cm->flags & cm->mask;

/* check whether provided bits are allowed to be passed */
- if (cm->mask & ~(priv->ctrlmode_supported | ctrlstatic))
+ if (maskedflags & ~(priv->ctrlmode_supported | ctrlstatic))
return -EOPNOTSUPP;

/* do not check for static fd-non-iso if 'fd' is disabled */
--
2.31.1