Re: status in PACKET_RX_RING is actually a bit mask

[Carsten Andrich <carsten.andrich-hs6bpBdVsEZfm0AUMx9V0g@public.gmane.org>]

I'd ack the patch, too.
However if we start clarifying the bitmask situation, we should do it
properly. packet.7 mentions TP_STATUS_xyz several times and never
actually differentiates between setting bits and setting the whole
tp_status variable. Actually both occurs inside the kernel:
http://lingrok.org/xref/linux-net-next/net/packet/af_packet.c#798
http://lingrok.org/xref/linux-net-next/net/packet/af_packet.c#2300

I could prepare another patch for review, that clarifies the tp_status
usage for all references to TP_STATUS_xyz values.
Unless Stefan would like to do this himself, since it's actually his
"discovery" ;)

Cheers,
Carsten

Daniel Borkmann schrieb:
> On 04/24/2014 10:04 AM, Michael Kerrisk (man-pages) wrote:
>>> Now to your question. It can easily be seen from the if_packet.h header
>>> file http://lingrok.org/xref/linux-net-next/include/uapi/linux/if_packet.h#93
>>> that TP_STATUS_* are individual bits that are set in tp_status field.
>>
>> So, I take it that that's an Ack-for the patch by Stefan?
> 
> Feel free to add my Ack. One nit below:
> 
> diff --git a/man7/packet.7 b/man7/packet.7
> index 1d3f222..6bac465 100644
> --- a/man7/packet.7
> +++ b/man7/packet.7
> @@ -353,9 +353,9 @@ The packet socket owns all slots with status
>  .BR TP_STATUS_KERNEL .
>  After filling a slot, it changes the status of the slot to transfer
>  ownership to the application.
> -During normal operation, the new status is
> -.BR TP_STATUS_USER ,
> -to signal that a correctly received packet has been stored.
> +During normal operation, the new status has the
> +.BR TP_STATUS_USER
> +bit set to signal that a correctly received packet has been stored.
> 
> ^--- I would drop the 'correctly' here as it rather raises questions
>      what 'incorrectly' would mean in this context.
> 
>  When the application has finished processing a packet, it transfers
>  ownership of the slot back to the socket by setting the status to
> 
> 
>>
>> Cheers,
>>
>> Michael
>>

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