[Bug 649099] [NEW] network freezes when creating tap devices and adding them to a bridge in parallel

[salva]

Public bug reported:

Sometimes when creating several new tap devices and adding them to a
bridge interface in parallel the network freezes for some seconds.

The attached C program can be used to replicate the problem.

In a host with a bridge interface configured as its main network
interface, compile the program and then run it from the shell as root as
follows:

  # while ping -c 1 10.1.0.1; do ./a.out 20 bridge0; done

substituting bridge0 by the name of bridge interface and the IP 10.1.0.1
by the IP of some machine reachable though the bridge (for instance the
default router).

Also keep pinging the bridge interface from another machine so that the
problem becomes easily noticeable.

Eventually, the traffic through the bridge interface will stop for some
seconds (~8s).

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: linux-image-2.6.32-24-generic 2.6.32-24.42
Regression: No
Reproducible: Yes
ProcVersionSignature: Ubuntu 2.6.32-24.42-generic 2.6.32.15+drm33.5
Uname: Linux 2.6.32-24-generic x86_64
AlsaDevices: Error: command ['ls', '-l', '/dev/snd/'] failed with exit code 2: ls: cannot access /dev/snd/: No such file or directory
AplayDevices: Error: [Errno 2] No such file or directory
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory
Date: Mon Sep 27 18:42:03 2010
Lsusb:
 Bus 002 Device 003: ID 0424:2514 Standard Microsystems Corp. 
 Bus 002 Device 002: ID 8087:0020  
 Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 001 Device 002: ID 8087:0020  
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Dell Inc. PowerEdge R210
PciMultimedia:
 
ProcCmdLine: BOOT_IMAGE=/vmlinuz-2.6.32-24-generic root=/dev/mapper/qvd--test2-root ro quiet
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: linux
dmi.bios.date: 05/24/2010
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.3.4
dmi.board.name: 0M877N
dmi.board.vendor: Dell Inc.
dmi.board.version: A02
dmi.chassis.type: 23
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr1.3.4:bd05/24/2010:svnDellInc.:pnPowerEdgeR210:pvr:rvnDellInc.:rn0M877N:rvrA02:cvnDellInc.:ct23:cvr:
dmi.product.name: PowerEdge R210
dmi.sys.vendor: Dell Inc.

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug lucid needs-upstream-testing networking

-- 
network freezes when creating tap devices and adding them to a bridge in parallel
https://bugs.launchpad.net/bugs/649099
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