389cb1ecc8
Ido Schimmel says: ==================== Add notifications when route hardware flags change Routes installed to the kernel can be programmed to capable devices, in which case they are marked with one of two flags. RTM_F_OFFLOAD for routes that offload traffic from the kernel and RTM_F_TRAP for routes that trap packets to the kernel for processing (e.g., host routes). These flags are of interest to routing daemons since they would like to delay advertisement of routes until they are installed in hardware. This allows them to avoid packet loss or misrouted packets. Currently, routing daemons do not receive any notifications when these flags are changed, requiring them to poll the kernel tables for changes which is inefficient. This series addresses the issue by having the kernel emit RTM_NEWROUTE notifications whenever these flags change. The behavior is controlled by two sysctls (net.ipv4.fib_notify_on_flag_change and net.ipv6.fib_notify_on_flag_change) that default to 0 (no notifications). Note that even if route installation in hardware is improved to be more synchronous, these notifications are still of interest. For example, a multipath route can change from RTM_F_OFFLOAD to RTM_F_TRAP if its neighbours become invalid. A routing daemon can choose to withdraw / replace the route in that case. In addition, the deletion of a route from the kernel can prompt the installation of an identical route (already in kernel, with an higher metric) to hardware. For testing purposes, netdevsim is aligned to simulate a "real" driver that programs routes to hardware. Series overview: Patches #1-#2 align netdevsim to perform route programming in a non-atomic context Patches #3-#5 add sysctl to control IPv4 notifications Patches #6-#8 add sysctl to control IPv6 notifications Patch #9 extends existing fib tests to set sysctls before running tests Patch #10 adds test for fib notifications over netdevsim ==================== Link: https://lore.kernel.org/r/20210201194757.3463461-1-idosch@idosch.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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.