// SPDX-License-Identifier: GPL-2.0 #include <linux/compiler.h>#include <stdio.h>#include <stdlib.h>#include <sys/prctl.h>#include <sys/wait.h>#include <unistd.h> #include "../tests.h" static int loops = 100;static char buf;int context_switch_loop_work = 1234; #define write_block(fd) \	do { \		if (write(fd, &buf, 1) <= 0) \			return 1; \	} while (0) #define read_block(fd) \	do { \		if (read(fd, &buf, 1) <= 0) \			return 1; \	} while (0) /* Not static to avoid LTO clobbering the function name */int context_switch_loop_proc1(int in_fd, int out_fd);int context_switch_loop_proc1(int in_fd, int out_fd){	for (int i = 0; i < loops; i++) {		read_block(in_fd);		context_switch_loop_work += i * 3;		write_block(out_fd);	}	return 0;} int context_switch_loop_proc2(int in_fd, int out_fd);int context_switch_loop_proc2(int in_fd, int out_fd){	for (int i = 0; i < loops; i++) {		write_block(out_fd);		context_switch_loop_work += i * 7;		read_block(in_fd);	}	return 0;} /* * Launches two processes that take turns to execute a multiplication N times */static int context_switch_loop(int argc, const char **argv){	int a_to_b[2], b_to_a[2];	pid_t proc1_pid;	int status;	int ret; 	if (argc > 0) {		loops = atoi(argv[0]);		if (loops < 0) {			fprintf(stderr, "Invalid number of loops: %s\n", argv[0]);			return 1;		}	} 	if (pipe(a_to_b) || pipe(b_to_a)) {		perror("Pipe error");		return 1;	} 	proc1_pid = fork();	if (proc1_pid < 0) {		perror("Fork error");		return 1;	} 	if (!proc1_pid) {		close(a_to_b[0]);		close(b_to_a[1]);		prctl(PR_SET_NAME, "proc1", 0, 0, 0);		ret = context_switch_loop_proc1(b_to_a[0], a_to_b[1]);		close(a_to_b[1]);		close(b_to_a[0]);		exit(ret);	} 	close(a_to_b[1]);	close(b_to_a[0]);	prctl(PR_SET_NAME, "proc2", 0, 0, 0);	ret = context_switch_loop_proc2(a_to_b[0], b_to_a[1]);	close(a_to_b[0]);	close(b_to_a[1]); 	if (ret) {		kill(proc1_pid, SIGKILL);		return ret;	} 	if (waitpid(proc1_pid, &status, 0) != proc1_pid || !WIFEXITED(status) ||	    WEXITSTATUS(status))		return 1; 	return 0;} DEFINE_WORKLOAD(context_switch_loop);