pm_qos: clean up racy global "name" variable

"name" is a poor name for a file-global variable.  It was used in three
different functions, with no mutual exclusion.  But it's just a tiny,
temporary string; let's just move it onto the stack in the functions that
need it.  Also use snprintf() just in case.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
LKML-Reference: <20091010153349.113570550@linutronix.de>
Acked-by: Mark Gross <mgross@linux.intel.com>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
index d96b83ed21cbaae5738acb56aec5a4ce946283d2..3db49b9ca374ded32bf224f266e904a8006e61a8 100644 (file)
--- a/kernel/pm_qos_params.c
+++ b/kernel/pm_qos_params.c
@@ -343,18 +343,18 @@ int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
 }
 EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
 
-#define PID_NAME_LEN sizeof("process_1234567890")
-static char name[PID_NAME_LEN];
+#define PID_NAME_LEN 32
 
 static int pm_qos_power_open(struct inode *inode, struct file *filp)
 {
        int ret;
        long pm_qos_class;
+       char name[PID_NAME_LEN];
 
        pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
        if (pm_qos_class >= 0) {
                filp->private_data = (void *)pm_qos_class;
-               sprintf(name, "process_%d", current->pid);
+               snprintf(name, PID_NAME_LEN, "process_%d", current->pid);
                ret = pm_qos_add_requirement(pm_qos_class, name,
                                        PM_QOS_DEFAULT_VALUE);
                if (ret >= 0)
@@ -366,9 +366,10 @@ static int pm_qos_power_open(struct inode *inode, struct file *filp)
 static int pm_qos_power_release(struct inode *inode, struct file *filp)
 {
        int pm_qos_class;
+       char name[PID_NAME_LEN];
 
        pm_qos_class = (long)filp->private_data;
-       sprintf(name, "process_%d", current->pid);
+       snprintf(name, PID_NAME_LEN, "process_%d", current->pid);
        pm_qos_remove_requirement(pm_qos_class, name);
 
        return 0;
@@ -379,13 +380,14 @@ static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 {
        s32 value;
        int pm_qos_class;
+       char name[PID_NAME_LEN];
 
        pm_qos_class = (long)filp->private_data;
        if (count != sizeof(s32))
                return -EINVAL;
        if (copy_from_user(&value, buf, sizeof(s32)))
                return -EFAULT;
-       sprintf(name, "process_%d", current->pid);
+       snprintf(name, PID_NAME_LEN, "process_%d", current->pid);
        pm_qos_update_requirement(pm_qos_class, name, value);
 
        return  sizeof(s32);