forked from luck/tmp_suning_uos_patched
0ea460474d
Jakub Kicinski says: ==================== udp_tunnel: add NIC RX port offload infrastructure Kernel has a facility to notify drivers about the UDP tunnel ports so that devices can recognize tunneled packets. This is important mostly for RX - devices which don't support CHECKSUM_COMPLETE can report checksums of inner packets, and compute RSS over inner headers. Some drivers also match the UDP tunnel ports also for TX, although doing so may lead to false positives and negatives. Unfortunately the user experience when trying to take adavantage of these facilities is suboptimal. First of all there is no way for users to check which ports are offloaded. Many drivers resort to printing messages to aid debugging, other use debugfs. Even worse the availability of the RX features (NETIF_F_RX_UDP_TUNNEL_PORT) is established purely on the basis of the driver having the ndos installed. For most drivers, however, the ability to perform offloads is contingent on device capabilities (driver support multiple device and firmware versions). Unless driver resorts to hackish clearing of features set incorrectly by the core - users are left guessing whether their device really supports UDP tunnel port offload or not. There is currently no way to indicate or configure whether RX features include just the checksum offload or checksum and using inner headers for RSS. Many drivers default to not using inner headers for RSS because most implementations populate the source port with entropy from the inner headers. This, however, is not always the case, for example certain switches are only able to use a fixed source port during encapsulation. We have also seen many driver authors get the intricacies of UDP tunnel port offloads wrong. Most commonly the drivers forget to perform reference counting, or take sleeping locks in the callbacks. This work tries to improve the situation by pulling the UDP tunnel port table maintenance out of the drivers. It turns out that almost all drivers maintain a fixed size table of ports (in most cases one per tunnel type), so we can take care of all the refcounting in the core, and let the driver specify if they need to sleep in the callbacks or not. The new common implementation will also support replacing ports - when a port is removed from a full table it will try to find a previously missing port to take its place. This patch only implements the core functionality along with a few drivers I was hoping to test manually [1] along with a test based on a netdevsim implementation. Following patches will convert all the drivers. Once that's complete we can remove the ndos, and rely directly on the new infrastrucutre. Then after RSS (RXFH) is converted to netlink we can add the ability to configure the use of inner RSS headers for UDP tunnels. [1] Unfortunately I wasn't able to, turns out 2 of the devices I had access to were older generation or had old FW, and they did not actually support UDP tunnel port notifications (see the second paragraph). The thrid device appears to program the UDP ports correctly but it generates bad UDP checksums with or without these patches. Long story short - I'd appreciate reviews and testing here.. v4: - better build fix (hopefully this one does it..) v3: - fix build issue; - improve bnxt changes. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.