On 3/4/20 10:08 AM, Andrii Nakryiko wrote:
On Wed, Mar 4, 2020 at 9:53 AM Yonghong Song <yhs@xxxxxx> wrote:Added one test, send_signal_sched_switch, to test bpf_send_signal() helper triggered by sched/sched_switch tracepoint. This test can be used to verify kernel deadlocks fixed by the previous commit. The test itself is heavily borrowed from Commit eac9153f2b58 ("bpf/stackmap: Fix deadlock with rq_lock in bpf_get_stack()"). Cc: Song Liu <songliubraving@xxxxxx> Signed-off-by: Yonghong Song <yhs@xxxxxx> --- .../bpf/prog_tests/send_signal_sched_switch.c | 89 +++++++++++++++++++ .../bpf/progs/test_send_signal_kern.c | 6 ++ 2 files changed, 95 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/send_signal_sched_switch.c diff --git a/tools/testing/selftests/bpf/prog_tests/send_signal_sched_switch.c b/tools/testing/selftests/bpf/prog_tests/send_signal_sched_switch.c new file mode 100644 index 000000000000..f5c9dbdeb173 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/send_signal_sched_switch.c @@ -0,0 +1,89 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <test_progs.h> +#include <stdio.h> +#include <stdlib.h> +#include <sys/mman.h> +#include <pthread.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> +#include "test_send_signal_kern.skel.h" + +static void sigusr1_handler(int signum) +{ +} + +#define THREAD_COUNT 100 + +static char *filename; + +static void *worker(void *p) +{ + int err, fd, i = 0; + u32 duration = 0; + char *pptr; + void *ptr; + + fd = open(filename, O_RDONLY); + if (CHECK(fd < 0, "open", "open failed %s\n", strerror(errno))) + return NULL; + + while (i < 100) { + struct timespec ts = {0, 1000 + rand() % 2000}; + + ptr = mmap(NULL, 4096 * 64, PROT_READ, MAP_PRIVATE, fd, 0); + err = errno; + usleep(1); + if (CHECK(ptr == MAP_FAILED, "mmap", "mmap failed: %s\n", + strerror(err))) + break; + + munmap(ptr, 4096 * 64); + usleep(1); + pptr = malloc(1); + usleep(1); + pptr[0] = 1; + usleep(1); + free(pptr); + usleep(1); + nanosleep(&ts, NULL); + i++;Any specific reason to do mmap()/munmap() in a loop? Would, say, getpid syscall work just fine as well to trigger a bunch of context switches? Or event just usleep(1) alone?
No particular reason. Copied from Song's original reproducer and it is working. Maybe Song can comment why it is written this way.
+ } + close(fd); + return NULL; +} + +void test_send_signal_sched_switch(void) +{ + struct test_send_signal_kern *skel; + pthread_t threads[THREAD_COUNT]; + u32 duration = 0; + int i, err; + + filename = "/bin/ls"; + signal(SIGUSR1, sigusr1_handler); + + skel = test_send_signal_kern__open_and_load(); + if (CHECK(!skel, "skel_open_and_load", "skeleton open_and_load failed\n")) + return; + + skel->bss->pid = getpid(); + skel->bss->sig = SIGUSR1; + + err = test_send_signal_kern__attach(skel); + if (CHECK(err, "skel_attach", "skeleton attach failed\n")) + goto destroy_skel; + + for (i = 0; i < THREAD_COUNT; i++) { + err = pthread_create(threads + i, NULL, worker, NULL); + if (CHECK(err, "pthread_create", "Error creating thread, %s\n", + strerror(errno))) + goto destroy_skel; + } + + for (i = 0; i < THREAD_COUNT; i++) + pthread_join(threads[i], NULL); + +destroy_skel: + test_send_signal_kern__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/test_send_signal_kern.c b/tools/testing/selftests/bpf/progs/test_send_signal_kern.c index 1acc91e87bfc..b4233d3efac2 100644 --- a/tools/testing/selftests/bpf/progs/test_send_signal_kern.c +++ b/tools/testing/selftests/bpf/progs/test_send_signal_kern.c @@ -31,6 +31,12 @@ int send_signal_tp(void *ctx) return bpf_send_signal_test(ctx); } +SEC("tracepoint/sched/sched_switch") +int send_signal_tp_sched(void *ctx) +{ + return bpf_send_signal_test(ctx); +} + SEC("perf_event") int send_signal_perf(void *ctx) { -- 2.17.1
