@@ -1,3 +1,4 @@
# SPDX-License-Identifier: GPL-2.0-only
sigtrap_threads
remove_on_exec
+watermark_signal
@@ -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
new file mode 100644
@@ -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
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