Fork of alistair23 Linux kernel for reMarkable from https://github.com/alistair23/linux
0e3183cd2a
Skbs may have their checksum value populated by HW. If this is a checksum calculated over the entire packet then the CHECKSUM_COMPLETE field is marked. Changes to the data pointer on the skb throughout the network stack still try to maintain this complete csum value if it is required through functions such as skb_postpush_rcsum. The MPLS actions in Open vSwitch modify a CHECKSUM_COMPLETE value when changes are made to packet data without a push or a pull. This occurs when the ethertype of the MAC header is changed or when MPLS lse fields are modified. The modification is carried out using the csum_partial function to get the csum of a buffer and add it into the larger checksum. The buffer is an inversion of the data to be removed followed by the new data. Because the csum is calculated over 16 bits and these values align with 16 bits, the effect is the removal of the old value from the CHECKSUM_COMPLETE and addition of the new value. However, the csum fed into the function and the outcome of the calculation are also inverted. This would only make sense if it was the new value rather than the old that was inverted in the input buffer. Fix the issue by removing the bit inverts in the csum_partial calculation. The bug was verified and the fix tested by comparing the folded value of the updated CHECKSUM_COMPLETE value with the folded value of a full software checksum calculation (reset skb->csum to 0 and run skb_checksum_complete(skb)). Prior to the fix the outcomes differed but after they produce the same result. Fixes: |
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| README | ||
README
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.