netdev - can multi app capture on same NIC?(use packet

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Message-ID: <4A6A2125329CFD4D8CC40C9E8ABCAB9F24985FE8F8@MILEXCH2.ds.jdsu.net>
Date:	Tue, 22 Jun 2010 02:40:13 -0700
From:	Jon Zhou <Jon.Zhou@...u.com>
To:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: can multi app capture on same NIC?(use packet_mmap)

Hi there

I'd like to know multi-app can work with packet_mmap (or traditional AF_PACKET system call)?
i.e.
app1 & app2 capture on the same NIC

will both of them receive the same packet? 

Or this situation will happen?

1.app1 start to receive a packet#1
2.app1 complete receiving, then set the packet_status->TP_STATUS_KERNEL
3.how about app2 at this time? Will it see packet_status=KERNEL, then packet#1 got lost?

I tried to find the relevant code in af_packet.c, seems it doesn't guarantee multi-app capture on same NIC?
Can someone help to point it out?

Thanks
jon 

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