cpufreq: update to sysfs_emit() for safer buffer handling

Replace sprintf() and scnprintf() with sysfs_emit() and sysfs_emit_at()
in the cpufreq core.

This ensures safer buffer handling and consistency with sysfs interfaces.

Update show_scaling_available_governors() and related functions for
compliance with the new API.

Signed-off-by: Perry Yuan <perry.yuan@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://patch.msgid.link/20240619081520.259971-1-perry.yuan@amd.com
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq.c

@@ -608,7 +608,7 @@ EXPORT_SYMBOL_GPL(cpufreq_policy_transition_delay_us);
 static ssize_t show_boost(struct kobject *kobj,
 			  struct kobj_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%d\n", cpufreq_driver->boost_enabled);
+	return sysfs_emit(buf, "%d\n", cpufreq_driver->boost_enabled);
 }
 
 static ssize_t store_boost(struct kobject *kobj, struct kobj_attribute *attr,
@@ -739,7 +739,7 @@ static struct cpufreq_governor *cpufreq_parse_governor(char *str_governor)
 static ssize_t show_##file_name				\
 (struct cpufreq_policy *policy, char *buf)		\
 {							\
-	return sprintf(buf, "%u\n", policy->object);	\
+	return sysfs_emit(buf, "%u\n", policy->object);	\
 }
 
 show_one(cpuinfo_min_freq, cpuinfo.min_freq);
@@ -760,11 +760,11 @@ static ssize_t show_scaling_cur_freq(struct cpufreq_policy *policy, char *buf)
 
 	freq = arch_freq_get_on_cpu(policy->cpu);
 	if (freq)
-		ret = sprintf(buf, "%u\n", freq);
+		ret = sysfs_emit(buf, "%u\n", freq);
 	else if (cpufreq_driver->setpolicy && cpufreq_driver->get)
-		ret = sprintf(buf, "%u\n", cpufreq_driver->get(policy->cpu));
+		ret = sysfs_emit(buf, "%u\n", cpufreq_driver->get(policy->cpu));
 	else
-		ret = sprintf(buf, "%u\n", policy->cur);
+		ret = sysfs_emit(buf, "%u\n", policy->cur);
 	return ret;
 }
 
@@ -798,9 +798,9 @@ static ssize_t show_cpuinfo_cur_freq(struct cpufreq_policy *policy,
 	unsigned int cur_freq = __cpufreq_get(policy);
 
 	if (cur_freq)
-		return sprintf(buf, "%u\n", cur_freq);
+		return sysfs_emit(buf, "%u\n", cur_freq);
 
-	return sprintf(buf, "<unknown>\n");
+	return sysfs_emit(buf, "<unknown>\n");
 }
 
 /*
@@ -809,12 +809,11 @@ static ssize_t show_cpuinfo_cur_freq(struct cpufreq_policy *policy,
 static ssize_t show_scaling_governor(struct cpufreq_policy *policy, char *buf)
 {
 	if (policy->policy == CPUFREQ_POLICY_POWERSAVE)
-		return sprintf(buf, "powersave\n");
+		return sysfs_emit(buf, "powersave\n");
 	else if (policy->policy == CPUFREQ_POLICY_PERFORMANCE)
-		return sprintf(buf, "performance\n");
+		return sysfs_emit(buf, "performance\n");
 	else if (policy->governor)
-		return scnprintf(buf, CPUFREQ_NAME_PLEN, "%s\n",
-				policy->governor->name);
+		return sysfs_emit(buf, "%s\n", policy->governor->name);
 	return -EINVAL;
 }
 
@@ -873,7 +872,7 @@ static ssize_t show_scaling_available_governors(struct cpufreq_policy *policy,
 	struct cpufreq_governor *t;
 
 	if (!has_target()) {
-		i += sprintf(buf, "performance powersave");
+		i += sysfs_emit(buf, "performance powersave");
 		goto out;
 	}
 
@@ -882,11 +881,11 @@ static ssize_t show_scaling_available_governors(struct cpufreq_policy *policy,
 		if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char))
 		    - (CPUFREQ_NAME_LEN + 2)))
 			break;
-		i += scnprintf(&buf[i], CPUFREQ_NAME_PLEN, "%s ", t->name);
+		i += sysfs_emit_at(buf, i, "%s ", t->name);
 	}
 	mutex_unlock(&cpufreq_governor_mutex);
 out:
-	i += sprintf(&buf[i], "\n");
+	i += sysfs_emit_at(buf, i, "\n");
 	return i;
 }
 
@@ -896,7 +895,7 @@ ssize_t cpufreq_show_cpus(const struct cpumask *mask, char *buf)
 	unsigned int cpu;
 
 	for_each_cpu(cpu, mask) {
-		i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), "%u ", cpu);
+		i += sysfs_emit_at(buf, i, "%u ", cpu);
 		if (i >= (PAGE_SIZE - 5))
 			break;
 	}
@@ -904,7 +903,7 @@ ssize_t cpufreq_show_cpus(const struct cpumask *mask, char *buf)
 	/* Remove the extra space at the end */
 	i--;
 
-	i += sprintf(&buf[i], "\n");
+	i += sysfs_emit_at(buf, i, "\n");
 	return i;
 }
 EXPORT_SYMBOL_GPL(cpufreq_show_cpus);
@@ -947,7 +946,7 @@ static ssize_t store_scaling_setspeed(struct cpufreq_policy *policy,
 static ssize_t show_scaling_setspeed(struct cpufreq_policy *policy, char *buf)
 {
 	if (!policy->governor || !policy->governor->show_setspeed)
-		return sprintf(buf, "<unsupported>\n");
+		return sysfs_emit(buf, "<unsupported>\n");
 
 	return policy->governor->show_setspeed(policy, buf);
 }
@@ -961,8 +960,8 @@ static ssize_t show_bios_limit(struct cpufreq_policy *policy, char *buf)
 	int ret;
 	ret = cpufreq_driver->bios_limit(policy->cpu, &limit);
 	if (!ret)
-		return sprintf(buf, "%u\n", limit);
-	return sprintf(buf, "%u\n", policy->cpuinfo.max_freq);
+		return sysfs_emit(buf, "%u\n", limit);
+	return sysfs_emit(buf, "%u\n", policy->cpuinfo.max_freq);
 }
 
 cpufreq_freq_attr_ro_perm(cpuinfo_cur_freq, 0400);