Fix cpuset sched_relax_domain_level control file

Due to a merge conflict, the sched_relax_domain_level control file was marked
as being handled by cpuset_read/write_u64, but the code to handle it was
actually in cpuset_common_file_read/write.

Since the value being written/read is in fact a signed integer, it should be
treated as such; this patch adds cpuset_read/write_s64 functions, and uses
them to handle the sched_relax_domain_level file.

With this patch, the sched_relax_domain_level can be read and written, and the
correct contents seen/updated.

Signed-off-by: Paul Menage <[e-mail]>
Cc: Hidetoshi Seto <[e-mail]>
Cc: Paul Jackson <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Reviewed-by: Li Zefan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

kernel/cpuset.c

···
 	return task_cs(current) == cpuset_being_rebound;
 }
 
-static int update_relax_domain_level(struct cpuset *cs, char *buf)
+static int update_relax_domain_level(struct cpuset *cs, s64 val)
 {
-	int val = simple_strtol(buf, NULL, 10);
-
-	if (val < 0)
+	if ((int)val < 0)
 		val = -1;
 
 	if (val != cs->relax_domain_level) {
···
 	case FILE_MEMLIST:
 		retval = update_nodemask(cs, buffer);
 		break;
-	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
-		retval = update_relax_domain_level(cs, buffer);
-		break;
 	default:
 		retval = -EINVAL;
 		goto out2;
···
 	case FILE_SPREAD_SLAB:
 		retval = update_flag(CS_SPREAD_SLAB, cs, val);
 		cs->mems_generation = cpuset_mems_generation++;
+		break;
+	default:
+		retval = -EINVAL;
+		break;
+	}
+	cgroup_unlock();
+	return retval;
+}
+
+static int cpuset_write_s64(struct cgroup *cgrp, struct cftype *cft, s64 val)
+{
+	int retval = 0;
+	struct cpuset *cs = cgroup_cs(cgrp);
+	cpuset_filetype_t type = cft->private;
+
+	cgroup_lock();
+
+	if (cgroup_is_removed(cgrp)) {
+		cgroup_unlock();
+		return -ENODEV;
+	}
+	switch (type) {
+	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
+		retval = update_relax_domain_level(cs, val);
 		break;
 	default:
 		retval = -EINVAL;
···
 	case FILE_MEMLIST:
 		s += cpuset_sprintf_memlist(s, cs);
 		break;
-	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
-		s += sprintf(s, "%d", cs->relax_domain_level);
-		break;
 	default:
 		retval = -EINVAL;
 		goto out;
···
 		return is_spread_page(cs);
 	case FILE_SPREAD_SLAB:
 		return is_spread_slab(cs);
+	default:
+		BUG();
+	}
+}
+
+static s64 cpuset_read_s64(struct cgroup *cont, struct cftype *cft)
+{
+	struct cpuset *cs = cgroup_cs(cont);
+	cpuset_filetype_t type = cft->private;
+	switch (type) {
+	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
+		return cs->relax_domain_level;
 	default:
 		BUG();
 	}
···
 
 	{
 		.name = "sched_relax_domain_level",
-		.read_u64 = cpuset_read_u64,
-		.write_u64 = cpuset_write_u64,
+		.read_s64 = cpuset_read_s64,
+		.write_s64 = cpuset_write_s64,
 		.private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
 	},