Re: [PATCH] net: dsa: tag_ocelot_8021q: fix broken reception

[Robert Hodaszi <robert.hodaszi@digi.com>]

2024. 12. 11. 15:37 keltezéssel, Vladimir Oltean írta:
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> On Wed, Dec 11, 2024 at 01:46:56PM +0100, Robert Hodaszi wrote:
>> Commit dcfe7673787b4bfea2c213df443d312aa754757b ("net: dsa: tag_sja1105:
>> absorb logic for not overwriting precise info into dsa_8021q_rcv()")
>> added support to let the DSA switch driver set source_port and
>> switch_id. tag_8021q's logic overrides the previously set source_port
>> and switch_id only if they are marked as "invalid" (-1). sja1105 and
>> vsc73xx drivers are doing that properly, but ocelot_8021q driver doesn't
>> initialize those variables. That causes dsa_8021q_rcv() doesn't set
>> them, and they remain unassigned.
>>
>> Initialize them as invalid to so dsa_8021q_rcv() can return with the
>> proper values.
>>
>> Signed-off-by: Robert Hodaszi <robert.hodaszi@digi.com>
>> Cc: stable@vger.kernel.org
>> ---
> Thank you for the patch, and sorry for the breakage. I suggest the
> following alternative commit message:
>
>   The blamed commit changed the dsa_8021q_rcv() calling convention to
>   accept pre-populated source_port and switch_id arguments. If those are
>   not available, as in the case of tag_ocelot_8021q, the arguments must
>   be preinitialized with -1.
>
>   Due to the bug of passing uninitialized arguments, dsa_8021q_rcv()
>   does not detect that it needs to populate the source_port and
>   switch_id, and this makes dsa_conduit_find_user() fail, and leads to
>   packet loss on reception.
>
>   Fixes: dcfe7673787b ("net: dsa: tag_sja1105: absorb logic for not overwriting precise info into dsa_8021q_rcv()")
>   Signed-off-by: Robert Hodaszi <robert.hodaszi@digi.com>
>   Cc: stable@vger.kernel.org

Yes, that commit message makes much more sense than mine. Unfortunately, I already sent out the new patch. I rewrite it, and send out a v2 then.

Robert