selftests/bpf: Add timer lockup selftest

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Add a selftest that tries to trigger a situation where two timer callbacks
are attempting to cancel each other's timer. By running them continuously,
we hit a condition where both run in parallel and cancel each other.

Without the fix in the previous patch, this would cause a lockup as
hrtimer_cancel on either side will wait for forward progress from the
callback.

Ensure that this situation leads to a EDEADLK error.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240711052709.2148616-1-memxor@gmail.com

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Kumar Kartikeya Dwivedi 2024-07-11 05:27:09 +00:00 • committed by Daniel Borkmann

parent 0c237341d9

commit 50bd5a0c65

2 changed files with 178 additions and 0 deletions

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91

tools/testing/selftests/bpf/prog_tests/timer_lockup.c

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87

tools/testing/selftests/bpf/progs/timer_lockup.c

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