netdev - Bisect'ed BUG in VLAN promisc mode (6c78dcbd47)

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Date:	Fri, 26 Sep 2008 16:00:36 +0200
From:	Jesper Dangaard Brouer <jdb@...x.dk>
To:	Patrick McHardy <kaber@...sh.net>
Cc:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Bisect'ed BUG in VLAN promisc mode (6c78dcbd47)

Hi Patrick,

Bisected me down to one of you changes
 commit 6c78dcbd47a68a
 [VLAN]: Fix promiscous/allmulti synchronization races

Description:
------------
 All other VLAN interfaces stop working, if a vlan is taken down
 (ifconfig eth1.1025 down) _while_ there is a tcpdump running on that
 interface.

 The problem is a result of promisc mode being removed on the
 real-device (eth1), when the vlan interface is taken down.  This
 should not happen as other vlan devices exists that still need
 promisc mode on the real-device (eth1).

Setup:
------
  eth1      - the real-device
  eth1.1013 - VLAN device
  eth1.1025 - VLAN device

 Both VLAN devices has assigned ether address 00:11:22:33:44:55 (which
 is different from the real-device).

Reproduce / test:
-----------------
Lookfor "promiscuous mode" changes in kern.log
# tail -n 40 -f /var/log/kern.log | grep "promiscuous mode"

Start a tcpdump on VLAN device
# tcpdump -ni eth1.1025

# LOG:
#   kernel: device eth1.1025 entered promiscuous mode

Take VLAN device down
# ifconfig eth1.1025 down

Tcpdump dies, the problem is that promisc mode is removed from both
the real-device and the VLAN device.  That should NOT happen, as there
are other VLAN devices up (eth1.1013).

# LOG:
#   kernel: device eth1.1025 left promiscuous mode
#   kernel: device eth1 left promiscuous mode

Bisect log: Attached

Commit 6c78dcbd47: Attached


See you in Paris!
-- 
Med venlig hilsen / Best regards
  Jesper Brouer
  ComX Networks A/S
  Linux Network developer
  Cand. Scient Datalog / MSc.
  Author of http://adsl-optimizer.dk
  LinkedIn: http://www.linkedin.com/in/brouer

View attachment "bisect03-found-bug.log" of type "text/x-log" (1706 bytes)

View attachment "bisect03-found-bug.patch" of type "text/x-patch" (4902 bytes)