vnet: ethernet-input incorrectly sets l3_hdr_offset in some cases

The issue surfaced when developing the tap GSO code, with
an iteration where output path is reliant on
vnet_buffer (b0)->l3_hdr_offset being set correctly in
the input path, during performance testing.

Adding a workaround in the TX path shows that
the issue surfaces only for relatively few packets
during the test (about 100 out of 600000).

Analysis shows the issue arises if the ethernet-input
is handling two untagged packets with different sw_if_index
values - then the accelerated path punts to slow path,
before the setting of the l2.l2_len values is done,
thus resulting in them being 0, and l3_hdr_offset being
the same as l2_hdr_offset, wreaking havoc on TX path.

The solution is to move the l2_hdr_offset calculation
into a place where it is done for all the packets,
and move the l3_hdr_offset calculation into
the determine_next_node() function - as that function is
also the one setting the special-case l2.l2_len value for
tagged packets and moving the current_data for the L2 case.

Change-Id: If728c7715e011930c1887691188c98055bddde67
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>
1 file changed
tree: aa04e55b8f97ebe342ef838fc3143025be76c350
  1. build/
  2. build-data/
  3. build-root/
  4. docs/
  5. doxygen/
  6. extras/
  7. gmod/
  8. src/
  9. test/
  10. .clang-format
  11. .gitignore
  12. .gitreview
  13. INFO.yaml
  14. LICENSE
  15. MAINTAINERS
  16. Makefile
  17. README.md
  18. RELEASE.md
README.md

Vector Packet Processing

Introduction

The VPP platform is an extensible framework that provides out-of-the-box production quality switch/router functionality. It is the open source version of Cisco's Vector Packet Processing (VPP) technology: a high performance, packet-processing stack that can run on commodity CPUs.

The benefits of this implementation of VPP are its high performance, proven technology, its modularity and flexibility, and rich feature set.

For more information on VPP and its features please visit the FD.io website and What is VPP? pages.

Changes

Details of the changes leading up to this version of VPP can be found under @ref release_notes.

Directory layout

Directory nameDescription
build-dataBuild metadata
build-rootBuild output directory
doxygenDocumentation generator configuration
dpdkDPDK patches and build infrastructure
@ref extras/libmemifClient library for memif
@ref src/examplesVPP example code
@ref src/pluginsVPP bundled plugins directory
@ref src/svmShared virtual memory allocation library
src/testsStandalone tests (not part of test harness)
src/vatVPP API test program
@ref src/vlibVPP application library
@ref src/vlibapiVPP API library
@ref src/vlibmemoryVPP Memory management
@ref src/vnetVPP networking
@ref src/vppVPP application
@ref src/vpp-apiVPP application API bindings
@ref src/vppinfraVPP core library
@ref src/vpp/apiNot-yet-relocated API bindings
testUnit tests and Python test harness

Getting started

In general anyone interested in building, developing or running VPP should consult the VPP wiki for more complete documentation.

In particular, readers are recommended to take a look at [Pulling, Building, Running, Hacking, Pushing](https://wiki.fd.io/view/VPP/Pulling,_Building,_Run ning,_Hacking_and_Pushing_VPP_Code) which provides extensive step-by-step coverage of the topic.

For the impatient, some salient information is distilled below.

Quick-start: On an existing Linux host

To install system dependencies, build VPP and then install it, simply run the build script. This should be performed a non-privileged user with sudo access from the project base directory:

./extras/vagrant/build.sh

If you want a more fine-grained approach because you intend to do some development work, the Makefile in the root directory of the source tree provides several convenience shortcuts as make targets that may be of interest. To see the available targets run:

make

Quick-start: Vagrant

The directory extras/vagrant contains a VagrantFile and supporting scripts to bootstrap a working VPP inside a Vagrant-managed Virtual Machine. This VM can then be used to test concepts with VPP or as a development platform to extend VPP. Some obvious caveats apply when using a VM for VPP since its performance will never match that of bare metal; if your work is timing or performance sensitive, consider using bare metal in addition or instead of the VM.

For this to work you will need a working installation of Vagrant. Instructions for this can be found [on the Setting up Vagrant wiki page] (https://wiki.fd.io/view/DEV/Setting_Up_Vagrant).

More information

Several modules provide documentation, see @subpage user_doc for more end-user-oriented information. Also see @subpage dev_doc for developer notes.

Visit the VPP wiki for details on more advanced building strategies and other development notes.

Test Framework

There is PyDoc generated documentation available for the VPP test framework. See @ref test_framework_doc for details.