Hi,
I have just one question yet :-)
On Fri, Jun 13, 2008 at 6:42 PM, Evgeniy Polyakov <johnpol@xxxxxxxxxxx> wrote:
> +int pohmelfs_copy_config(struct pohmelfs_sb *psb)
> +{
> + struct pohmelfs_config *c, *dst;
> + int err = -ENODEV;
> +
> + mutex_lock(&pohmelfs_config_lock);
> + list_for_each_entry(c, &pohmelfs_config_list, config_entry) {
> + if (c->state.ctl.idx != psb->idx)
> + continue;
> +
> + err = 0;
> + list_for_each_entry(dst, &psb->state_list, config_entry) {
> + if (pohmelfs_config_eql(&dst->state.ctl, &c->state.ctl)) {
> + err = -EEXIST;
> + break;
> + }
> + }
> +
> + if (err)
> + continue;
> +
> + dst = kzalloc(sizeof(struct pohmelfs_config), GFP_KERNEL);
> + if (!dst) {
> + err = -ENOMEM;
> + goto err_out_unlock;
> + }
> +
> + memcpy(&dst->state.ctl, &c->state.ctl, sizeof(struct pohmelfs_ctl));
> +
> + list_add_tail(&dst->config_entry, &psb->state_list);
> +
> + err = pohmelfs_state_init_one(psb, dst);
> + if (err) {
> + list_del(&dst->config_entry);
> + kfree(dst);
> + }
> + }
> + mutex_unlock(&pohmelfs_config_lock);
> +
> + return err;
> +
> +err_out_unlock:
> + mutex_unlock(&pohmelfs_config_lock);
> +
> + mutex_lock(&psb->state_lock);
> + list_for_each_entry_safe(dst, c, &psb->state_list, config_entry) {
> + list_del(&dst->config_entry);
> + kfree(dst);
> + }
> + mutex_unlock(&psb->state_lock);
> +
> + return err;
> +}
I'm having a hard time convincing myself that the error handling here
is correct. You have this kind of setup:
1. for each config in config list {
2. for each config in superblock state list {
pohmelfs_config_eql();
...
}
}
And according to your code, if pohmelfs_config_eql returns non-zero in
the last iteration of #1, then -EEXISTS will be the return value of
the whole function (but the config _will_ be copied; it is not undone
in this case). But if pohmenlfs_config_eql returns non-zero in any but
the last iteration of #1, then 0 will be the return value. Is this
your intention?
Vegard
--
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
-- E. W. Dijkstra, EWD1036
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