Re: [PATCH] Revert "can: dev: __can_get_echo_skb(): print error message, if trying to echo non existing skb"

From: Marc Kleine-Budde
Date: Fri Jan 04 2019 - 10:23:36 EST

On 12/19/18 7:39 PM, Manfred Schlaegl wrote:
> This reverts commit 7da11ba5c5066dadc2e96835a6233d56d7b7764a.
> After introduction of this change we encountered following new error
> message on various i.MX plattforms (flexcan)
> flexcan 53fc8000.can can0: __can_get_echo_skb: BUG! Trying to echo non
> existing skb: can_priv::echo_skb[0]

Doh! I should have tested more extensive. Sorry.

> The introduction of the message was a mistake because
> priv->echo_skb[idx] = NULL is a perfectly valid in following case:
> If CAN_RAW_LOOPBACK is disabled (setsockopt) in applications, the
> pkt_type of the tx skb's given to can_put_echo_skb is set to
> PACKET_LOOPBACK. In this case can_put_echo_skb will not set
> priv->echo_skb[idx]. It is therefore kept NULL.
> (As additional argument for revert: The order of check and usage of idx
> was changed. idx is used to access an array element before checking it's
> boundaries)
> Signed-off-by: Manfred Schlaegl <manfred.schlaegl@xxxxxxxxxxxxx>

Applied to linux-can.


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