diff options
| author | Artem Savkov <asavkov@redhat.com> | 2024-01-10 09:57:37 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-01-23 14:40:23 -0800 |
| commit | d177c1be06ce28aa8c8710ac55be1b5ad3f314c6 (patch) | |
| tree | ab822b88b22a6f8892eda0a9752092fedb63bf3a | |
| parent | f5f30386c78105cba520e443a6a9ee945ec1d066 (diff) | |
selftests/bpf: Fix potential premature unload in bpf_testmod
It is possible for bpf_kfunc_call_test_release() to be called from
bpf_map_free_deferred() when bpf_testmod is already unloaded and
perf_test_stuct.cnt which it tries to decrease is no longer in memory.
This patch tries to fix the issue by waiting for all references to be
dropped in bpf_testmod_exit().
The issue can be triggered by running 'test_progs -t map_kptr' in 6.5,
but is obscured in 6.6 by d119357d07435 ("rcu-tasks: Treat only
synchronous grace periods urgently").
Fixes: 65eb006d85a2 ("bpf: Move kernel test kfuncs to bpf_testmod")
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/82f55c0e-0ec8-4fe1-8d8c-b1de07558ad9@linux.dev
Link: https://lore.kernel.org/bpf/20240110085737.8895-1-asavkov@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
| -rw-r--r-- | tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c index 91907b321f91..e7c9e1c7fde0 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c @@ -2,6 +2,7 @@ /* Copyright (c) 2020 Facebook */ #include <linux/btf.h> #include <linux/btf_ids.h> +#include <linux/delay.h> #include <linux/error-injection.h> #include <linux/init.h> #include <linux/module.h> @@ -544,6 +545,14 @@ static int bpf_testmod_init(void) static void bpf_testmod_exit(void) { + /* Need to wait for all references to be dropped because + * bpf_kfunc_call_test_release() which currently resides in kernel can + * be called after bpf_testmod is unloaded. Once release function is + * moved into the module this wait can be removed. + */ + while (refcount_read(&prog_test_struct.cnt) > 1) + msleep(20); + return sysfs_remove_bin_file(kernel_kobj, &bin_attr_bpf_testmod_file); } |