From: Yonghong Song <yonghong.song@xxxxxxxxx>
[ Upstream commit 56925f389e152dcb8d093435d43b78a310539c23 ]
With previous patch, one of subtests in test_btf_id becomes
flaky and may fail. The following is a failing example:
Error: #26 btf
Error: #26/174 btf/BTF ID
Error: #26/174 btf/BTF ID
btf_raw_create:PASS:check 0 nsec
btf_raw_create:PASS:check 0 nsec
test_btf_id:PASS:check 0 nsec
...
test_btf_id:PASS:check 0 nsec
test_btf_id:FAIL:check BTF lingersdo_test_get_info:FAIL:check failed: -1
The test tries to prove a btf_id not available after the map is closed.
But btf_id is freed only after workqueue and a rcu grace period, compared
to previous case just after a rcu grade period.
Depending on system workload, workqueue could take quite some time
to execute function bpf_map_free_deferred() which may cause the test failure.
Instead of adding arbitrary delays, let us remove the logic to
check btf_id availability after map is closed.
Signed-off-by: Yonghong Song <yonghong.song@xxxxxxxxx>
Link: https://lore.kernel.org/r/20231214203820.1469402-1-yonghong.song@xxxxxxxxx
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
[Samasth: backport for 6.6.y]
Signed-off-by: Samasth Norway Ananda <samasth.norway.ananda@xxxxxxxxxx>
---
Above patch is a fix for 59e5791f59dd ("bpf: Fix a race condition between
btf_put() and map_free()"). While the commit causing the error is
present in 6.6.y the fix is not present.
---
tools/testing/selftests/bpf/prog_tests/btf.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c b/tools/testing/selftests/bpf/prog_tests/btf.c
index 92d51f377fe5..0c0881c7eb1a 100644
--- a/tools/testing/selftests/bpf/prog_tests/btf.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf.c
@@ -4630,11 +4630,6 @@ static int test_btf_id(unsigned int test_num)
/* The map holds the last ref to BTF and its btf_id */
close(map_fd);
map_fd = -1;
- btf_fd[0] = bpf_btf_get_fd_by_id(map_info.btf_id);
- if (CHECK(btf_fd[0] >= 0, "BTF lingers")) {
- err = -1;
- goto done;
- }
fprintf(stderr, "OK");
--
2.42.0
