Re: [PATCH v5 5/7] can: netlink: add interface for CAN-FD Transmitter Delay Compensation (TDC)

On 18.08.2021 17:37:17, Vincent MAILHOL wrote:

quoted

It's not a race. Consider this command:

| ip up tdc-mode manual tdco 111 tdcv 33  # 111 is out of range, 33 is valid

tdcv is checked first and valid, then it's assigned to the priv->tdc.
tdco is checked second and invalid, then can_tdc_changelink() returns -EINVAL.

tdc ends up being half set :(

So the setting of tdc is inconsistent and when you do a "ip down" "ip
up" then it results in a tdco=0 tdcv=33 mode=manual.

My bad. Now I understand the issue.
I was confused because tdco=111 is in the valid range of my driver...

:D

I will squash your patch.

Actually, I think that there is one more thing which needs to be
fixed: If can_tdc_changelink() fails (e.g. value out of range),
the CAN_CTRLMODE_TDC_AUTO or CAN_CTRLMODE_TDC_MANUAL would still
be set, meaning that can_tdc_is_enabled() would return true. So I
will add a "fail" branch to clear the flags.

Ok.

regard,
Marc

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