On Wed, Nov 7, 2012 at 7:30 AM, David Sterba <dave@xxxxxxxx> wrote:
> On Mon, Oct 29, 2012 at 12:30:54PM +0800, zwu.kernel@xxxxxxxxx wrote:
>> +static int ioctl_heat_info(struct file *file, void __user *argp)
>> +{
>> + struct inode *inode = file->f_dentry->d_inode;
>> + struct hot_heat_info *heat_info;
>> + struct hot_inode_item *he;
>> + int ret = 0;
>> +
>> + heat_info = kmalloc(sizeof(struct hot_heat_info),
>> + GFP_KERNEL | GFP_NOFS);
>
> heat_info is small enough to fit onto the stack, so you can avoid the
> kmalloc, I don't think there are deep callstacks to be expected.
ok, done.
> Nevertheless, if you want to use kmalloc here, then please check the
> return value and use GFP_KERNEL.
thanks for your pointing out.
>
>> +
>> + if (copy_from_user((void *) heat_info,
>> + argp,
>> + sizeof(struct hot_heat_info)) != 0) {
>> + ret = -EFAULT;
>> + goto err;
>> + }
>> +
>> + he = hot_inode_item_find(inode->i_sb->s_hot_root, inode->i_ino);
>> + if (!he) {
>> + /* we don't have any info on this file yet */
>> + ret = -ENODATA;
>> + goto err;
>> + }
>> +
>> + spin_lock(&he->hot_inode.lock);
>> + heat_info->avg_delta_reads =
>> + (__u64) he->hot_inode.hot_freq_data.avg_delta_reads;
>> + heat_info->avg_delta_writes =
>> + (__u64) he->hot_inode.hot_freq_data.avg_delta_writes;
>> + heat_info->last_read_time =
>> + (__u64) timespec_to_ns(&he->hot_inode.hot_freq_data.last_read_time);
>> + heat_info->last_write_time =
>> + (__u64) timespec_to_ns(&he->hot_inode.hot_freq_data.last_write_time);
>> + heat_info->num_reads =
>> + (__u32) he->hot_inode.hot_freq_data.nr_reads;
>> + heat_info->num_writes =
>> + (__u32) he->hot_inode.hot_freq_data.nr_writes;
>> +
>> + if (heat_info->live > 0) {
>> + /*
>> + * got a request for live temperature,
>> + * call hot_hash_calc_temperature to recalculate
>> + */
>> + heat_info->temp =
>> + inode->i_sb->s_hot_root->hot_func_type->ops.hot_temp_calc_fn(
>> + &he->hot_inode.hot_freq_data);
>> + } else {
>> + /* not live temperature, get it from the hashlist */
>> + heat_info->temp = he->hot_inode.hot_freq_data.last_temp;
>> + }
>> + spin_unlock(&he->hot_inode.lock);
>> +
>> + hot_inode_item_put(he);
>> +
>> + if (copy_to_user(argp, (void *) heat_info,
>> + sizeof(struct hot_heat_info))) {
>> + ret = -EFAULT;
>> + goto err;
>> + }
>> +
>> +err:
>> + kfree(heat_info);
>> + return ret;
>> +}
>
> david
--
Regards,
Zhi Yong Wu
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