tools/testing/selftests/perf_events/watermark_signal.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/perf_events/watermark_signal.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/perf_events/watermark_signal.c
Extension
.c
Size
2817 bytes
Lines
145
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

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 synchronize 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 == MAP_FAILED) {
		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

Annotation

Implementation Notes