| Date | Sat, 10 Oct 2009 21:54:22 +0200 (CEST) | From | John Kacur <> | Subject | Re: [patch 02/28] pm_qos: clean up racy global "name" variable |
| |
On Sat, 10 Oct 2009, Thomas Gleixner wrote:
> "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> > Cc: 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 d96b83e..3db49b9 100644 > --- 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
Hmnn, why 32? Seems arbitrary. At least you see with "process_1234567890" which is 19, an attempt to show what the maximum string size would be. If a system were configured to enlarge the maximum PID from 32767 to 4194303 that would still only be 7 digits, so "process_1234567" - which is 16 digits with the newline would enough.
So, I suggest you change that to #define PID_NAME_LEN sizeof("process_1234567")
Other than that, Reviewed-by: John Kacur <jkacur@redhat.com>
> > 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); > > >
|