selftests: breakpoint_test: use ksft_* var arg msg api

Use ksft_* var arg msg to include strerror() info. in test output. Change
output from child process to use ksft_print_msg() instead of ksft_exit_*
to avoid double counting tests and ensure parent does the incrementing
test counters. Also includes unused variable cleanup.

Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

tools/testing/selftests/breakpoints/breakpoint_test.c

@@ -16,6 +16,8 @@
 #include <signal.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <errno.h>
+#include <string.h>
 
 #include "../kselftest.h"
 
@@ -43,7 +45,8 @@ static void set_breakpoint_addr(void *addr, int n)
 	ret = ptrace(PTRACE_POKEUSER, child_pid,
 		     offsetof(struct user, u_debugreg[n]), addr);
 	if (ret)
-		ksft_exit_fail_msg("Can't set breakpoint addr");
+		ksft_exit_fail_msg("Can't set breakpoint addr: %s\n",
+			strerror(errno));
 }
 
 static void toggle_breakpoint(int n, int type, int len,
@@ -103,8 +106,10 @@ static void toggle_breakpoint(int n, int type, int len,
 
 	ret = ptrace(PTRACE_POKEUSER, child_pid,
 		     offsetof(struct user, u_debugreg[7]), dr7);
-	if (ret)
-		ksft_exit_fail_msg("Can't set dr7");
+	if (ret) {
+		ksft_print_msg("Can't set dr7: %s\n", strerror(errno));
+		exit(-1);
+	}
 }
 
 /* Dummy variables to test read/write accesses */
@@ -202,7 +207,7 @@ static void trigger_tests(void)
 
 	ret = ptrace(PTRACE_TRACEME, 0, NULL, 0);
 	if (ret) {
-		perror("Can't be traced?\n");
+		ksft_print_msg("Can't be traced? %s\n", strerror(errno));
 		return;
 	}
 
@@ -257,7 +262,6 @@ static void trigger_tests(void)
 
 static void check_success(const char *msg)
 {
-	const char *msg2;
 	int child_nr_tests;
 	int status;
 	int ret;
@@ -265,7 +269,6 @@ static void check_success(const char *msg)
 	/* Wait for the child to SIGTRAP */
 	wait(&status);
 
-	msg2 = "Failed";
 	ret = 0;
 
 	if (WSTOPSIG(status) == SIGTRAP) {
@@ -274,7 +277,7 @@ static void check_success(const char *msg)
 		if (child_nr_tests == nr_tests)
 			ret = 1;
 		if (ptrace(PTRACE_POKEDATA, child_pid, &trapped, 1))
-			ksft_exit_fail_msg("Can't poke");
+			ksft_exit_fail_msg("Can't poke: %s\n", strerror(errno));
 	}
 
 	nr_tests++;
@@ -293,7 +296,7 @@ static void launch_instruction_breakpoints(char *buf, int local, int global)
 		set_breakpoint_addr(dummy_funcs[i], i);
 		toggle_breakpoint(i, BP_X, 1, local, global, 1);
 		ptrace(PTRACE_CONT, child_pid, NULL, 0);
-		sprintf(buf, "Test breakpoint %d with local: %d global: %d",
+		sprintf(buf, "Test breakpoint %d with local: %d global: %d\n",
 			i, local, global);
 		check_success(buf);
 		toggle_breakpoint(i, BP_X, 1, local, global, 0);
@@ -315,8 +318,9 @@ static void launch_watchpoints(char *buf, int mode, int len,
 		set_breakpoint_addr(&dummy_var[i], i);
 		toggle_breakpoint(i, mode, len, local, global, 1);
 		ptrace(PTRACE_CONT, child_pid, NULL, 0);
-		sprintf(buf, "Test %s watchpoint %d with len: %d local: "
-			"%d global: %d", mode_str, i, len, local, global);
+		sprintf(buf,
+			"Test %s watchpoint %d with len: %d local: %d global: %d\n",
+			mode_str, i, len, local, global);
 		check_success(buf);
 		toggle_breakpoint(i, mode, len, local, global, 0);
 	}
@@ -382,7 +386,7 @@ int main(int argc, char **argv)
 	pid = fork();
 	if (!pid) {
 		trigger_tests();
-		return 0;
+		exit(0);
 	}
 
 	child_pid = pid;
@@ -393,5 +397,5 @@ int main(int argc, char **argv)
 
 	wait(NULL);
 
-	return ksft_exit_pass();
+	ksft_exit_pass();
 }