linux-stable.git/tools/testing/selftests/bpf/map_tests/task_storage_map.c, branch v6.18 Linux kernel stable tree selftests/bpf: Check for PREEMPTION instead of PREEMPT 2024-11-26T16:55:01+00:00 Sebastian Andrzej Siewior bigeasy@linutronix.de 2024-11-19T16:18:19+00:00 6b64128a74ebcacc5a0de5a74834e3b9f47a354c CONFIG_PREEMPT is a preemtion model the so called "Low-Latency Desktop". A different preemption model is PREEMPT_RT the so called "Real-Time". Both implement preemption in kernel and set CONFIG_PREEMPTION. There is also the so called "LAZY PREEMPT" which the "Scheduler controlled preemption model". Here we have also preemption in the kernel the rules are slightly different. Therefore the testsuite should not check for CONFIG_PREEMPT (as one model) but for CONFIG_PREEMPTION to figure out if preemption in the kernel is possible. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Link: https://lore.kernel.org/r/20241119161819.qvEcs-n_@linutronix.de Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
CONFIG_PREEMPT is a preemtion model the so called "Low-Latency Desktop".
A different preemption model is PREEMPT_RT the so called "Real-Time".
Both implement preemption in kernel and set CONFIG_PREEMPTION.
There is also the so called "LAZY PREEMPT" which the "Scheduler
controlled preemption model". Here we have also preemption in the kernel
the rules are slightly different.

Therefore the testsuite should not check for CONFIG_PREEMPT (as one
model) but for CONFIG_PREEMPTION to figure out if preemption in the
kernel is possible.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20241119161819.qvEcs-n_@linutronix.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
selftests/bpf: Clean up open-coded gettid syscall invocations 2024-11-04T19:37:36+00:00 Kumar Kartikeya Dwivedi memxor@gmail.com 2024-11-04T17:19:58+00:00 0e2fb011a0ba8e2258ce776fdf89fbd589c2a3a6 Availability of the gettid definition across glibc versions supported by BPF selftests is not certain. Currently, all users in the tree open-code syscall to gettid. Convert them to a common macro definition. Reviewed-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/r/20241104171959.2938862-3-memxor@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Availability of the gettid definition across glibc versions supported by
BPF selftests is not certain. Currently, all users in the tree open-code
syscall to gettid. Convert them to a common macro definition.

Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241104171959.2938862-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
selftests/bpf: Destroy the skeleton when CONFIG_PREEMPT is off 2022-09-22T23:41:27+00:00 Hou Tao houtao1@huawei.com 2022-09-21T07:00:34+00:00 f5eb23b91c41a7ffc7ca7fe14f3c512360f02937 Destroy the created skeleton when CONFIG_PREEMPT is off, else will be resource leak. Fixes: 73b97bc78b32 ("selftests/bpf: Test concurrent updates on bpf_task_storage_busy") Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20220921070035.2016413-2-houtao@huaweicloud.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> 
Destroy the created skeleton when CONFIG_PREEMPT is off, else will be
resource leak.

Fixes: 73b97bc78b32 ("selftests/bpf: Test concurrent updates on bpf_task_storage_busy")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20220921070035.2016413-2-houtao@huaweicloud.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
selftests/bpf: Add test result messages for test_task_storage_map_stress_lookup 2022-09-19T18:17:38+00:00 Hou Tao houtao1@huawei.com 2022-09-19T03:57:14+00:00 a7e85406bdbd0c376f3997e571f7073b9527272e Add test result message when test_task_storage_map_stress_lookup() succeeds or is skipped. The test case can be skipped due to the choose of preemption model in kernel config, so export skips in test_maps.c and increase it when needed. The following is the output of test_maps when the test case succeeds or is skipped: test_task_storage_map_stress_lookup:PASS test_maps: OK, 0 SKIPPED test_task_storage_map_stress_lookup SKIP (no CONFIG_PREEMPT) test_maps: OK, 1 SKIPPED Fixes: 73b97bc78b32 ("selftests/bpf: Test concurrent updates on bpf_task_storage_busy") Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20220919035714.2195144-1-houtao@huaweicloud.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> 
Add test result message when test_task_storage_map_stress_lookup()
succeeds or is skipped. The test case can be skipped due to the choose
of preemption model in kernel config, so export skips in test_maps.c and
increase it when needed.

The following is the output of test_maps when the test case succeeds or
is skipped:

  test_task_storage_map_stress_lookup:PASS
  test_maps: OK, 0 SKIPPED

  test_task_storage_map_stress_lookup SKIP (no CONFIG_PREEMPT)
  test_maps: OK, 1 SKIPPED

Fixes: 73b97bc78b32 ("selftests/bpf: Test concurrent updates on bpf_task_storage_busy")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20220919035714.2195144-1-houtao@huaweicloud.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
selftests/bpf: Test concurrent updates on bpf_task_storage_busy 2022-09-01T19:16:21+00:00 Hou Tao houtao1@huawei.com 2022-09-01T06:19:38+00:00 73b97bc78b32eb739a7dd3394fa3981e8021c0ef Under full preemptible kernel, task local storage lookup operations on the same CPU may update per-cpu bpf_task_storage_busy concurrently. If the update of bpf_task_storage_busy is not preemption safe, the final value of bpf_task_storage_busy may become not-zero forever and bpf_task_storage_trylock() will always fail. So add a test case to ensure the update of bpf_task_storage_busy is preemption safe. Will skip the test case when CONFIG_PREEMPT is disabled, and it can only reproduce the problem probabilistically. By increasing TASK_STORAGE_MAP_NR_LOOP and running it under ARM64 VM with 4-cpus, it takes about four rounds to reproduce: > test_maps is modified to only run test_task_storage_map_stress_lookup() $ export TASK_STORAGE_MAP_NR_THREAD=256 $ export TASK_STORAGE_MAP_NR_LOOP=81920 $ export TASK_STORAGE_MAP_PIN_CPU=1 $ time ./test_maps test_task_storage_map_stress_lookup(135):FAIL:bad bpf_task_storage_busy got -2 real 0m24.743s user 0m6.772s sys 0m17.966s Signed-off-by: Hou Tao <houtao1@huawei.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/r/20220901061938.3789460-5-houtao@huaweicloud.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> 
Under full preemptible kernel, task local storage lookup operations on
the same CPU may update per-cpu bpf_task_storage_busy concurrently. If
the update of bpf_task_storage_busy is not preemption safe, the final
value of bpf_task_storage_busy may become not-zero forever and
bpf_task_storage_trylock() will always fail. So add a test case to
ensure the update of bpf_task_storage_busy is preemption safe.

Will skip the test case when CONFIG_PREEMPT is disabled, and it can only
reproduce the problem probabilistically. By increasing
TASK_STORAGE_MAP_NR_LOOP and running it under ARM64 VM with 4-cpus, it
takes about four rounds to reproduce:

> test_maps is modified to only run test_task_storage_map_stress_lookup()
$ export TASK_STORAGE_MAP_NR_THREAD=256
$ export TASK_STORAGE_MAP_NR_LOOP=81920
$ export TASK_STORAGE_MAP_PIN_CPU=1
$ time ./test_maps
test_task_storage_map_stress_lookup(135):FAIL:bad bpf_task_storage_busy got -2

real    0m24.743s
user    0m6.772s
sys     0m17.966s

Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20220901061938.3789460-5-houtao@huaweicloud.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>