On Mon, Oct 29, 2012 at 12:30:54PM +0800, zwu.ker...@gmail.com 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.
Nevertheless, if you want to use kmalloc here, then please check the
return value and use GFP_KERNEL.
> +
> + 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
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