[PATCH] cpufreq: update to sysfs_emit for safer buffer handling

From: Perry Yuan
Date: Wed Jun 19 2024 - 04:15:57 EST


Replaced sprintf and scnprintf with sysfs_emit and sysfs_emit_at in the
cpufreq driver. This ensures safer buffer handling and consistency with
sysfs interfaces. Updated show_scaling_available_governors and related
functions for compliance with the new API.

Signed-off-by: Perry Yuan <perry.yuan@xxxxxxx>
---
drivers/cpufreq/cpufreq.c | 37 ++++++++++++++++++-------------------
1 file changed, 18 insertions(+), 19 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index e1a4730f4f8c..e76d8e2b4c87 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/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,
@@ -738,7 +738,7 @@ 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);
@@ -759,11 +759,11 @@ 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;
}

@@ -797,9 +797,9 @@ 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");
}

/*
@@ -808,12 +808,11 @@ 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;
}

@@ -872,7 +871,7 @@ 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;
}

@@ -881,11 +880,11 @@ 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;
}

@@ -895,7 +894,7 @@ 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;
}
@@ -903,7 +902,7 @@ 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);
@@ -946,7 +945,7 @@ 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);
}
@@ -960,8 +959,8 @@ 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);
--
2.34.1