The test uses PERF_RECORD_SWITCH records to fill the ring buffer and trigger the watermark wakeup, which in turn should trigger an IO signal.
Signed-off-by: Kyle Huey khuey@kylehuey.com --- .../testing/selftests/perf_events/.gitignore | 1 + tools/testing/selftests/perf_events/Makefile | 2 +- .../selftests/perf_events/watermark_signal.c | 146 ++++++++++++++++++ 3 files changed, 148 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/perf_events/watermark_signal.c
diff --git a/tools/testing/selftests/perf_events/.gitignore b/tools/testing/selftests/perf_events/.gitignore index 790c47001e77..ee93dc4969b8 100644 --- a/tools/testing/selftests/perf_events/.gitignore +++ b/tools/testing/selftests/perf_events/.gitignore @@ -1,3 +1,4 @@ # SPDX-License-Identifier: GPL-2.0-only sigtrap_threads remove_on_exec +watermark_signal diff --git a/tools/testing/selftests/perf_events/Makefile b/tools/testing/selftests/perf_events/Makefile index db93c4ff081a..70e3ff211278 100644 --- a/tools/testing/selftests/perf_events/Makefile +++ b/tools/testing/selftests/perf_events/Makefile @@ -2,5 +2,5 @@ CFLAGS += -Wl,-no-as-needed -Wall $(KHDR_INCLUDES) LDFLAGS += -lpthread
-TEST_GEN_PROGS := sigtrap_threads remove_on_exec +TEST_GEN_PROGS := sigtrap_threads remove_on_exec watermark_signal include ../lib.mk diff --git a/tools/testing/selftests/perf_events/watermark_signal.c b/tools/testing/selftests/perf_events/watermark_signal.c new file mode 100644 index 000000000000..49dc1e831174 --- /dev/null +++ b/tools/testing/selftests/perf_events/watermark_signal.c @@ -0,0 +1,146 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE + +#include <errno.h> +#include <fcntl.h> +#include <linux/perf_event.h> +#include <stddef.h> +#include <sched.h> +#include <signal.h> +#include <stdlib.h> +#include <string.h> +#include <sys/ioctl.h> +#include <sys/mman.h> +#include <sys/syscall.h> +#include <sys/wait.h> +#include <unistd.h> + +#include "../kselftest_harness.h" + +#define __maybe_unused __attribute__((__unused__)) + +static int sigio_count; + +static void handle_sigio(int signum __maybe_unused, + siginfo_t *oh __maybe_unused, + void *uc __maybe_unused) +{ + ++sigio_count; +} + +static void do_child(void) +{ + raise(SIGSTOP); + + for (int i = 0; i < 20; ++i) + sleep(1); + + raise(SIGSTOP); + + exit(0); +} + +TEST(watermark_signal) +{ + struct perf_event_attr attr; + struct perf_event_mmap_page *p = NULL; + struct sigaction previous_sigio, sigio = { 0 }; + pid_t child = -1; + int child_status; + int fd = -1; + long page_size = sysconf(_SC_PAGE_SIZE); + + sigio.sa_sigaction = handle_sigio; + EXPECT_EQ(sigaction(SIGIO, &sigio, &previous_sigio), 0); + + memset(&attr, 0, sizeof(attr)); + attr.size = sizeof(attr); + attr.type = PERF_TYPE_SOFTWARE; + attr.config = PERF_COUNT_SW_DUMMY; + attr.sample_period = 1; + attr.disabled = 1; + attr.watermark = 1; + attr.context_switch = 1; + attr.wakeup_watermark = 1; + + child = fork(); + EXPECT_GE(child, 0); + if (child == 0) + do_child(); + else if (child < 0) { + perror("fork()"); + goto cleanup; + } + + if (waitpid(child, &child_status, WSTOPPED) != child || + !(WIFSTOPPED(child_status) && WSTOPSIG(child_status) == SIGSTOP)) { + fprintf(stderr, + "failed to sycnhronize with child errno=%d status=%x\n", + errno, + child_status); + goto cleanup; + } + + fd = syscall(__NR_perf_event_open, &attr, child, -1, -1, + PERF_FLAG_FD_CLOEXEC); + if (fd < 0) { + fprintf(stderr, "failed opening event %llx\n", attr.config); + goto cleanup; + } + + if (fcntl(fd, F_SETFL, FASYNC)) { + perror("F_SETFL FASYNC"); + goto cleanup; + } + + if (fcntl(fd, F_SETOWN, getpid())) { + perror("F_SETOWN getpid()"); + goto cleanup; + } + + if (fcntl(fd, F_SETSIG, SIGIO)) { + perror("F_SETSIG SIGIO"); + goto cleanup; + } + + p = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); + if (p == NULL) { + perror("mmap"); + goto cleanup; + } + + if (ioctl(fd, PERF_EVENT_IOC_ENABLE, 0)) { + perror("PERF_EVENT_IOC_ENABLE"); + goto cleanup; + } + + if (kill(child, SIGCONT) < 0) { + perror("SIGCONT"); + goto cleanup; + } + + if (waitpid(child, &child_status, WSTOPPED) != -1 || errno != EINTR) + fprintf(stderr, + "expected SIGIO to terminate wait errno=%d status=%x\n%d", + errno, + child_status, + sigio_count); + + EXPECT_GE(sigio_count, 1); + +cleanup: + if (p != NULL) + munmap(p, 2 * page_size); + + if (fd >= 0) + close(fd); + + if (child > 0) { + kill(child, SIGKILL); + waitpid(child, NULL, 0); + } + + sigaction(SIGIO, &previous_sigio, NULL); +} + +TEST_HARNESS_MAIN