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15cf39221e
Introduce a kernel module that will exercise lock acquisition in the NMI
path, and bias toward creating contention such that NMI waiters end up
being non-head waiters. Prior to the rqspinlock fix made in the commit
0d80e7f951 ("rqspinlock: Choose trylock fallback for NMI waiters"), it
was possible for the queueing path of non-head waiters to get stuck in
NMI, which this stress test reproduces fairly easily with just 3 CPUs.
Both AA and ABBA flavors are supported, and it will serve as a test case
for future fixes that address this corner case. More information about
the problem in question is available in the commit cited above. When the
fix is reverted, this stress test will lock up the system.
To enable this test automatically through the test_progs infrastructure,
add a load_module_params API to exercise both AA and ABBA cases when
running the test.
Note that the test runs for at most 5 seconds, and becomes a noop after
that, in order to allow the system to make forward progress. In
addition, CPU 0 is always kept untouched by the created threads and
NMIs. The test will automatically scale to the number of available
online CPUs.
Note that at least 3 CPUs are necessary to run this test, hence skip the
selftest in case the environment has less than 3 CPUs available.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250927205304.199760-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
62 lines
1.9 KiB
C
62 lines
1.9 KiB
C
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
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/* Copyright (C) 2020 Facebook, Inc. */
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#ifndef __TESTING_HELPERS_H
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#define __TESTING_HELPERS_H
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#include <stdbool.h>
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#include <bpf/bpf.h>
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#include <bpf/libbpf.h>
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#include <time.h>
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#define __TO_STR(x) #x
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#define TO_STR(x) __TO_STR(x)
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int parse_num_list(const char *s, bool **set, int *set_len);
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__u32 link_info_prog_id(const struct bpf_link *link, struct bpf_link_info *info);
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int bpf_prog_test_load(const char *file, enum bpf_prog_type type,
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struct bpf_object **pobj, int *prog_fd);
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int bpf_test_load_program(enum bpf_prog_type type, const struct bpf_insn *insns,
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size_t insns_cnt, const char *license,
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__u32 kern_version, char *log_buf,
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size_t log_buf_sz);
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/*
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* below function is exported for testing in prog_test test
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*/
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struct test_filter_set;
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int parse_test_list(const char *s,
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struct test_filter_set *test_set,
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bool is_glob_pattern);
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int parse_test_list_file(const char *path,
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struct test_filter_set *test_set,
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bool is_glob_pattern);
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__u64 read_perf_max_sample_freq(void);
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int load_bpf_testmod(bool verbose);
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int unload_bpf_testmod(bool verbose);
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int kern_sync_rcu(void);
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int finit_module(int fd, const char *param_values, int flags);
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int delete_module(const char *name, int flags);
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int load_module(const char *path, bool verbose);
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int load_module_params(const char *path, const char *param_values, bool verbose);
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int unload_module(const char *name, bool verbose);
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static inline __u64 get_time_ns(void)
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{
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struct timespec t;
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clock_gettime(CLOCK_MONOTONIC, &t);
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return (u64)t.tv_sec * 1000000000 + t.tv_nsec;
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}
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struct bpf_insn;
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/* Request BPF program instructions after all rewrites are applied,
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* e.g. verifier.c:convert_ctx_access() is done.
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*/
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int get_xlated_program(int fd_prog, struct bpf_insn **buf, __u32 *cnt);
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int testing_prog_flags(void);
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bool is_jit_enabled(void);
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#endif /* __TESTING_HELPERS_H */
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