On Fri, Jul 15, 2022 at 01:47:28PM +0200,
Daniel Bristot de Oliveira wrote:
> On 7/14/22 09:46, Tao Zhou wrote:
> > On Wed, Jul 13, 2022 at 11:17:17PM +0200,
> > Daniel Bristot de Oliveira <bristot@xxxxxxxxxx> wrote:
> >
> > [...]
> >
> >> +void put_task_monitor_slot(int slot)
> >> +{
> >> + lockdep_assert_held(&rv_interface_lock);
> >> +
> >> + if (slot < 0 || slot > RV_PER_TASK_MONITORS) {
> >
> > slot is the array index that should be 0 here. The up bound is not bigger
> > than 0 because the element of array now is RV_PER_TASK_MONITORS.
> >
> > So up bound check is 'slot > RV_PER_TASK_MONITORS-1'.
>
> fixed! (slot >= RV...)
>
> > [...]
> >
> >> +/*
> >> + * interface for enabling/disabling a monitor.
> >> + */
> >> +static ssize_t monitor_enable_write_data(struct file *filp, const char __user *user_buf,
> >> + size_t count, loff_t *ppos)
> >> +{
> >> + struct rv_monitor_def *mdef = filp->private_data;
> >> + int retval;
> >> + bool val;
> >> +
> >> + retval = kstrtobool_from_user(user_buf, count, &val);
> >> + if (retval)
> >> + return retval;
> >> +
> >> + retval = count;
> >> +
> >> + mutex_lock(&rv_interface_lock);
> >> +
> >> + if (val)
> >> + retval = enable_monitor(mdef);
> >> + else
> >> + retval = disable_monitor(mdef);
> >> +
> >> + mutex_unlock(&rv_interface_lock);
> >> +
> >> + return retval ? retval : count;
> >
> > Feel that this can be written `return retval ? : count;`
>
>
> why not...
>
> > [...]
> >
> >> +static void *enabled_monitors_start(struct seq_file *m, loff_t *pos)
> >> +{
> >> + struct rv_monitor_def *m_def;
> >> + loff_t l;
> >> +
> >> + mutex_lock(&rv_interface_lock);
> >> +
> >> + if (list_empty(&rv_monitors_list))
> >> + return NULL;
> >> +
> >> + m_def = list_entry(&rv_monitors_list, struct rv_monitor_def, list);
> >> +
> >> + for (l = 0; l <= *pos; ) {
> >> + m_def = enabled_monitors_next(m, m_def, &l);
> >> + if (!m_def)
> >> + break;
> >
> > Is this check is inversed. enabled_monitors_start() will stop at first
> > enabled monitor, then enabled_monitors_next() do loop to next. Check
> > like the above, enabled_monitors_start() will loop to the last monitor.
> > But I doubt myself I do not mention/see it. Sorry for these.
> >
> > the check is:
> >
> > if (m_def)
> > break;
> >
> > [...]
>
>
> see kernel/trace/trace_events.c:s_start...
I presumed @l changed in function enabled_monitors_next() will
impack on the @*pos of enabled_monitors_start(). But it's not.
@l is increased by 1 in enabled_monitors_next() and is used to
check with @*pos passed as parameter argument of enabled_monitors_start().
Absolutely I lost here.. Thanks.
> >> +static ssize_t
> >> +enabled_monitors_write(struct file *filp, const char __user *user_buf,
> >> + size_t count, loff_t *ppos)
> >> +{
> >> + char buff[MAX_RV_MONITOR_NAME_SIZE + 2];
> >> + struct rv_monitor_def *mdef;
> >> + int retval = -EINVAL;
> >> + bool enable = true;
> >> + char *ptr = buff;
> >> + int len;
> >> +
> >> + if (count < 1 || count > MAX_RV_MONITOR_NAME_SIZE + 2)
> >
> > @count would not include '\0'. That the max val of @count is
> > MAX_RV_MONITOR_NAME_SIZE+1. So the up bound check of @count is
> > `count > MAX_RV_MONITOR_NAME_SIZE + 1`.
>
> Fixed for v6...
>
> -- Daniel
