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Matt Bobrowski c80d797206 bpf/selftests: Fix test_tcpnotify_user 
Based on a bisect, it appears that commit 7ee9887703 ("timers:
Implement the hierarchical pull model") has somehow inadvertently
broken BPF selftest test_tcpnotify_user. The error that is being
generated by this test is as follows:

	FAILED: Wrong stats Expected 10 calls, got 8

It looks like the change allows timer functions to be run on CPUs
different from the one they are armed on. The test had pinned itself
to CPU 0, and in the past the retransmit attempts also occurred on CPU
0. The test had set the max_entries attribute for
BPF_MAP_TYPE_PERF_EVENT_ARRAY to 2 and was calling
bpf_perf_event_output() with BPF_F_CURRENT_CPU, so the entry was
likely to be in range. With the change to allow timers to run on other
CPUs, the current CPU tasked with performing the retransmit might be
bumped and in turn fall out of range, as the event will be filtered
out via __bpf_perf_event_output() using:

    if (unlikely(index >= array->map.max_entries))
            return -E2BIG;

A possible change would be to explicitly set the max_entries attribute
for perf_event_map in test_tcpnotify_kern.c to a value that's at least
as large as the number of CPUs. As it turns out however, if the field
is left unset, then the libbpf will determine the number of CPUs available
on the underlying system and update the max_entries attribute accordingly
in map_set_def_max_entries().

A further problem with the test is that it has a thread that continues
running up until the program exits. The main thread cleans up some
LIBBPF data structures, while the other thread continues to use them,
which inevitably will trigger a SIGSEGV. This can be dealt with by
telling the thread to run for as long as necessary and doing a
pthread_join on it before exiting the program.

Finally, I don't think binding the process to CPU 0 is meaningful for
this test any more, so get rid of that.

Fixes: 435f90a338 ("selftests/bpf: add a test case for sock_ops perf-event notification")
Signed-off-by: Matt Bobrowski <mattbobrowski@google.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/aJ8kHhwgATmA3rLf@google.com
2025-08-15 13:05:29 -07:00
arch riscv, bpf: Add support arena atomics for RV64 2025-08-15 10:46:51 +02:00
block block-6.17-20250808 2025-08-09 08:47:28 +03:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto Significant patch series in this pull request: 2025-08-03 16:23:09 -07:00
Documentation EFI updates for v6.17 2025-08-09 18:10:01 +03:00
drivers - Fix a wrong ioremap size in mvebu-gicp 2025-08-10 08:46:47 +03:00
fs NFS client updates for Linux 6.17 2025-08-09 07:20:44 +03:00
include bpf: Don't use %pK through printk 2025-08-13 15:34:56 -07:00
init Significant patch series in this pull request: 2025-08-03 16:23:09 -07:00
io_uring io_uring/memmap: cast nr_pages to size_t before shifting 2025-08-08 06:35:14 -06:00
ipc vfs-6.17-rc1.mmap_prepare 2025-07-28 13:43:25 -07:00
kernel bpf: Replace kvfree with kfree for kzalloc memory 2025-08-12 15:55:01 -07:00
lib block-6.17-20250808 2025-08-09 08:47:28 +03:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm Significant patch series in this pull request: 2025-08-05 16:02:07 +03:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2025-08-12 12:14:02 -07:00
rust Rust changes for v6.17 2025-08-03 13:49:10 -07:00
samples Significant patch series in this pull request: 2025-08-03 16:23:09 -07:00
scripts Kbuild updates for v6.17 2025-08-06 07:32:52 +03:00
security + Features 2025-08-04 08:17:28 -07:00
sound gpio updates for v6.17-rc1 2025-08-09 08:15:43 +03:00
tools bpf/selftests: Fix test_tcpnotify_user 2025-08-15 13:05:29 -07:00
usr usr/include: openrisc: don't HDRTEST bpf_perf_event.h 2025-05-12 15:03:17 +09:00
virt Merge tag 'kvm-x86-no_assignment-6.17' of https://github.com/kvm-x86/linux into HEAD 2025-07-29 08:36:42 -04:00
.clang-format Linux 6.15-rc5 2025-05-06 16:39:25 +10:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore gitignore: allow .pylintrc to be tracked 2025-07-02 17:10:04 -06:00
.mailmap Significant patch series in this pull request: 2025-08-03 16:23:09 -07:00
.pylintrc docs: add a .pylintrc file with sys path for docs scripts 2025-04-09 12:10:33 -06:00
.rustfmt.toml
COPYING
CREDITS Kbuild updates for v6.17 2025-08-06 07:32:52 +03:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS spi: Fixes for v6.17 2025-08-09 08:43:24 +03:00
Makefile Linux 6.17-rc1 2025-08-10 19:41:16 +03:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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 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.