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| author | Andrii Nakryiko <andrii@kernel.org> | 2021-01-11 23:55:17 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-01-12 17:23:47 -0800 |
| commit | 635599bace259a2c42741c3ea61bfa7be6f15556 (patch) | |
| tree | a50085d6b0dc9ca61778aad8a06cc285114c3084 /tools/testing/selftests/bpf/test_progs.c | |
| parent | 936f8946bdb48239f4292812d4d2e26c6d328c95 (diff) | |
| download | linux-635599bace259a2c42741c3ea61bfa7be6f15556.tar.gz | |
selftests/bpf: Sync RCU before unloading bpf_testmod
If some of the subtests use module BTFs through ksyms, they will cause
bpf_prog to take a refcount on bpf_testmod module, which will prevent it from
successfully unloading. Module's refcnt is decremented when bpf_prog is freed,
which generally happens in RCU callback. So we need to trigger
syncronize_rcu() in the kernel, which can be achieved nicely with
membarrier(MEMBARRIER_CMD_SHARED) or membarrier(MEMBARRIER_CMD_GLOBAL) syscall.
So do that in kernel_sync_rcu() and make it available to other test inside the
test_progs. This synchronize_rcu() is called before attempting to unload
bpf_testmod.
Fixes: 9f7fa225894c ("selftests/bpf: Add bpf_testmod kernel module for testing")
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/bpf/20210112075520.4103414-5-andrii@kernel.org
Diffstat (limited to 'tools/testing/selftests/bpf/test_progs.c')
| -rw-r--r-- | tools/testing/selftests/bpf/test_progs.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c index 7d077d48cadd..213628ee721c 100644 --- a/tools/testing/selftests/bpf/test_progs.c +++ b/tools/testing/selftests/bpf/test_progs.c @@ -11,6 +11,7 @@ #include <signal.h> #include <string.h> #include <execinfo.h> /* backtrace */ +#include <linux/membarrier.h> #define EXIT_NO_TEST 2 #define EXIT_ERR_SETUP_INFRA 3 @@ -370,8 +371,18 @@ static int delete_module(const char *name, int flags) return syscall(__NR_delete_module, name, flags); } +/* + * Trigger synchronize_rcu() in kernel. + */ +int kern_sync_rcu(void) +{ + return syscall(__NR_membarrier, MEMBARRIER_CMD_SHARED, 0, 0); +} + static void unload_bpf_testmod(void) { + if (kern_sync_rcu()) + fprintf(env.stderr, "Failed to trigger kernel-side RCU sync!\n"); if (delete_module("bpf_testmod", 0)) { if (errno == ENOENT) { if (env.verbosity > VERBOSE_NONE) |