selftests/powerpc: Allow bind_to_cpu() to automatically pick CPU

All current users of bind_to_cpu() don't care _which_ CPU they get, just
that they are bound to a single free one. So alter the interface to

	1. Accept a BIND_CPU_ANY value that tells it to automatically
	   pick a CPU
	2. Return the picked CPU

And convert all these users to bind_to_cpu(BIND_CPU_ANY).
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230406043320.125138-4-bgray@linux.ibm.com

tools/testing/selftests/powerpc/include/utils.h

@@ -31,6 +31,8 @@ int read_auxv(char *buf, ssize_t buf_size);
 void *find_auxv_entry(int type, char *auxv);
 void *get_auxv_entry(int type);
 
+#define BIND_CPU_ANY	(-1)
+
 int pick_online_cpu(void);
 int bind_to_cpu(int cpu);
 

tools/testing/selftests/powerpc/pmu/ebb/cpu_event_pinned_vs_ebb_test.c

@@ -45,9 +45,8 @@ int cpu_event_pinned_vs_ebb(void)
 
 	SKIP_IF(!ebb_is_supported());
 
-	cpu = pick_online_cpu();
+	cpu = bind_to_cpu(BIND_CPU_ANY);
 	FAIL_IF(cpu < 0);
-	FAIL_IF(bind_to_cpu(cpu));
 
 	FAIL_IF(pipe(read_pipe.fds) == -1);
 	FAIL_IF(pipe(write_pipe.fds) == -1);

tools/testing/selftests/powerpc/pmu/ebb/cpu_event_vs_ebb_test.c

@@ -43,9 +43,8 @@ int cpu_event_vs_ebb(void)
 
 	SKIP_IF(!ebb_is_supported());
 
-	cpu = pick_online_cpu();
+	cpu = bind_to_cpu(BIND_CPU_ANY);
 	FAIL_IF(cpu < 0);
-	FAIL_IF(bind_to_cpu(cpu));
 
 	FAIL_IF(pipe(read_pipe.fds) == -1);
 	FAIL_IF(pipe(write_pipe.fds) == -1);

tools/testing/selftests/powerpc/pmu/ebb/ebb_vs_cpu_event_test.c

@@ -43,9 +43,8 @@ int ebb_vs_cpu_event(void)
 
 	SKIP_IF(!ebb_is_supported());
 
-	cpu = pick_online_cpu();
+	cpu = bind_to_cpu(BIND_CPU_ANY);
 	FAIL_IF(cpu < 0);
-	FAIL_IF(bind_to_cpu(cpu));
 
 	FAIL_IF(pipe(read_pipe.fds) == -1);
 	FAIL_IF(pipe(write_pipe.fds) == -1);

tools/testing/selftests/powerpc/pmu/ebb/multi_ebb_procs_test.c

@@ -75,13 +75,11 @@ static int cycles_child(void)
 int multi_ebb_procs(void)
 {
 	pid_t pids[NR_CHILDREN];
-	int cpu, rc, i;
+	int rc, i;
 
 	SKIP_IF(!ebb_is_supported());
 
-	cpu = pick_online_cpu();
-	FAIL_IF(cpu < 0);
-	FAIL_IF(bind_to_cpu(cpu));
+	FAIL_IF(bind_to_cpu(BIND_CPU_ANY) < 0);
 
 	for (i = 0; i < NR_CHILDREN; i++) {
 		pids[i] = fork();

tools/testing/selftests/powerpc/pmu/lib.c

@@ -103,12 +103,10 @@ static int eat_cpu_child(union pipe read_pipe, union pipe write_pipe)
 pid_t eat_cpu(int (test_function)(void))
 {
 	union pipe read_pipe, write_pipe;
-	int cpu, rc;
+	int rc;
 	pid_t pid;
 
-	cpu = pick_online_cpu();
-	FAIL_IF(cpu < 0);
-	FAIL_IF(bind_to_cpu(cpu));
+	FAIL_IF(bind_to_cpu(BIND_CPU_ANY) < 0);
 
 	if (pipe(read_pipe.fds) == -1)
 		return -1;

tools/testing/selftests/powerpc/utils.c

@@ -455,13 +455,24 @@ int pick_online_cpu(void)
 int bind_to_cpu(int cpu)
 {
 	cpu_set_t mask;
+	int err;
+
+	if (cpu == BIND_CPU_ANY) {
+		cpu = pick_online_cpu();
+		if (cpu < 0)
+			return cpu;
+	}
 
 	printf("Binding to cpu %d\n", cpu);
 
 	CPU_ZERO(&mask);
 	CPU_SET(cpu, &mask);
 
-	return sched_setaffinity(0, sizeof(mask), &mask);
+	err = sched_setaffinity(0, sizeof(mask), &mask);
+	if (err)
+		return err;
+
+	return cpu;
 }
 
 bool is_ppc64le(void)