mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-04-30 22:50:54 -04:00
6fc2f3832d
IPv6 GRO considers packets to belong to different flows when their hop_limit is different. This seems counter-intuitive, the flow is the same. hop_limit may vary because of various bugs or hacks but that doesn't mean it's okay for GRO to reorder packets. Practical impact of this problem on overall TCP performance is unclear, but TCP itself detects this reordering and bumps TCPSACKReorder resulting in user complaints. Eric warns that there may be performance regressions in setups which do packet spraying across links with similar RTT but different hop count. To be safe let's target -next and not treat this as a fix. If the packet spraying is using flow label there should be no difference in behavior as flow label is checked first. Note that the code plays an easy to miss trick by upcasting next_hdr to a u16 pointer and compares next_hdr and hop_limit in one go. Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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.