a087d4b502
[ Upstream commit f7d625adeb7bc6a9ec83d32d9615889969d64484 ] The current implementation allocates page-sized rx buffers. As traffic may consist of different types and sizes of packets, in various cases, buffers are not fully used. This change (Dynamic RX Buffers - DRB) uses part of the allocated rx page needed for the incoming packet, and returns the rest of the unused page to be used again as an rx buffer for future packets. A threshold of 2K for unused space has been set in order to declare whether the remainder of the page can be reused again as an rx buffer. As a page may be reused, dma_sync_single_for_cpu() is added in order to sync the memory to the CPU side after it was owned by the HW. In addition, when the rx page can no longer be reused, it is being unmapped using dma_page_unmap(), which implicitly syncs and then unmaps the entire page. In case the kernel still handles the skbs pointing to the previous buffers from that rx page, it may access garbage pointers, caused by the implicit sync overwriting them. The implicit dma sync is removed by replacing dma_page_unmap() with dma_unmap_page_attrs() with DMA_ATTR_SKIP_CPU_SYNC flag. The functionality is disabled for XDP traffic to avoid handling several descriptors per packet. Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com> Signed-off-by: Shay Agroskin <shayagr@amazon.com> Signed-off-by: David Arinzon <darinzon@amazon.com> Link: https://lore.kernel.org/r/20230612121448.28829-1-darinzon@amazon.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Stable-dep-of: 2dc8b1e7177d ("net: ena: Fix redundant device NUMA node override") Signed-off-by: Sasha Levin <sashal@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.