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Add a test case to verify the atomic update of existing elements in the htab of maps. The test proceeds in three steps: 1) fill the outer map with keys in the range [0, 8] For each inner array map, the value of its first element is set as the key used to lookup the inner map. 2) create 16 threads to lookup these keys concurrently Each lookup thread first lookups the inner map, then it checks whether the first value of the inner array map is the same as the key used to lookup the inner map. 3) create 8 threads to overwrite these keys concurrently Each update thread first creates an inner array, it sets the first value of the array to the key used to update the outer map, then it uses the key and the inner map to update the outer map. Without atomic update support, the lookup operation may return -ENOENT during the lookup of outer map, or return -EINVAL during the comparison of the first value in the inner map and the key used for inner map, and the test will fail. After the atomic update change, both the lookup and the comparison will succeed. Given that the update of outer map is slow, the test case sets the loop number for each thread as 5 to reduce the total running time. However, the loop number could also be adjusted through FD_HTAB_LOOP_NR environment variable. Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20250401062250.543403-7-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@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 reStructuredText 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.