On Mon, Dec 04, 2023 at 09:16:52PM -0800, Yonghong Song wrote: > > On 12/3/23 3:48 PM, Jiri Olsa wrote: > > Adding test that tries to trigger the BUG_ON during early map update > > in prog_array_map_poke_run function. > > > > The idea is to share prog array map between thread that constantly > > updates it and another one loading a program that uses that prog > > array. > > > > Eventually we will hit a place where the program is ok to be updated > > (poke->tailcall_target_stable check) but the address is still not > > registered in kallsyms, so the bpf_arch_text_poke returns -EINVAL > > and cause imbalance for the next tail call update check, which will > > fail with -EBUSY in bpf_arch_text_poke as described in previous fix. > > > > Acked-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx> > > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> > > --- > > .../selftests/bpf/prog_tests/tailcall_poke.c | 74 +++++++++++++++++++ > > .../selftests/bpf/progs/tailcall_poke.c | 32 ++++++++ > > 2 files changed, 106 insertions(+) > > create mode 100644 tools/testing/selftests/bpf/prog_tests/tailcall_poke.c > > create mode 100644 tools/testing/selftests/bpf/progs/tailcall_poke.c > > > > diff --git a/tools/testing/selftests/bpf/prog_tests/tailcall_poke.c b/tools/testing/selftests/bpf/prog_tests/tailcall_poke.c > > new file mode 100644 > > index 000000000000..f7e2c09fd772 > > --- /dev/null > > +++ b/tools/testing/selftests/bpf/prog_tests/tailcall_poke.c > > @@ -0,0 +1,74 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +#include <unistd.h> > > +#include <test_progs.h> > > +#include "tailcall_poke.skel.h" > > + > > +#define JMP_TABLE "/sys/fs/bpf/jmp_table" > > + > > +static int thread_exit; > > + > > +static void *update(void *arg) > > +{ > > + __u32 zero = 0, prog1_fd, prog2_fd, map_fd; > > + struct tailcall_poke *call = arg; > > + > > + map_fd = bpf_map__fd(call->maps.jmp_table); > > + prog1_fd = bpf_program__fd(call->progs.call1); > > + prog2_fd = bpf_program__fd(call->progs.call2); > > + > > + while (!thread_exit) { > > + bpf_map_update_elem(map_fd, &zero, &prog1_fd, BPF_ANY); > > + bpf_map_update_elem(map_fd, &zero, &prog2_fd, BPF_ANY); > > + } > > + > > + return NULL; > > +} > > + > > +void test_tailcall_poke(void) > > +{ > > + struct tailcall_poke *call, *test; > > + int err, cnt = 10; > > + pthread_t thread; > > + > > + unlink(JMP_TABLE); > > + > > + call = tailcall_poke__open_and_load(); > > + if (!ASSERT_OK_PTR(call, "tailcall_poke__open")) > > + return; > > + > > + err = bpf_map__pin(call->maps.jmp_table, JMP_TABLE); > > + if (!ASSERT_OK(err, "bpf_map__pin")) > > + goto out; > > Just curious. What is the reason having bpf_map__pin() here > and below? I tried and it looks like removing bpf_map__pin() > and below bpf_map__set_pin_path() will make reproducing > the failure hard/impossible. yes, it's there to share the jmp_table map between the two skeleton instances, so the update thread changes the same jmp_table map that's used in the skeleton we load in the while loop below I'll add some comments to the test jirka > > > + > > + err = pthread_create(&thread, NULL, update, call); > > + if (!ASSERT_OK(err, "new toggler")) > > + goto out; > > + > > + while (cnt--) { > > + test = tailcall_poke__open(); > > + if (!ASSERT_OK_PTR(test, "tailcall_poke__open")) > > + break; > > + > > + err = bpf_map__set_pin_path(test->maps.jmp_table, JMP_TABLE); > > + if (!ASSERT_OK(err, "bpf_map__pin")) { > > + tailcall_poke__destroy(test); > > + break; > > + } > > + > > + bpf_program__set_autoload(test->progs.test, true); > > + bpf_program__set_autoload(test->progs.call1, false); > > + bpf_program__set_autoload(test->progs.call2, false); > > + > > + err = tailcall_poke__load(test); > > + tailcall_poke__destroy(test); > > + if (!ASSERT_OK(err, "tailcall_poke__load")) > > + break; > > + } > > + > > + thread_exit = 1; > > + ASSERT_OK(pthread_join(thread, NULL), "pthread_join"); > > + > > +out: > > + bpf_map__unpin(call->maps.jmp_table, JMP_TABLE); > > + tailcall_poke__destroy(call); > > +} SNIP