Re: [PATCH v7 3.2-rc2 3/30] uprobes: register/unregister probes.

[Peter Zijlstra]

On Fri, 2011-11-18 at 16:37 +0530, Srikar Dronamraju wrote:
> +int register_uprobe(struct inode *inode, loff_t offset,
> +                               struct uprobe_consumer *consumer)
> +{
> +       struct uprobe *uprobe;
> +       int ret = -EINVAL;
> +
> +       if (!consumer || consumer->next)
> +               return ret;
> +
> +       inode = igrab(inode);

So why are you dealing with !consumer but not with !inode? and why does
it make sense to allow !consumer at all?

> +       if (!inode)
> +               return ret;
> +
> +       if (offset > i_size_read(inode))
> +               goto reg_out;
> +
> +       ret = 0;
> +       mutex_lock(uprobes_hash(inode));
> +       uprobe = alloc_uprobe(inode, offset);
> +       if (uprobe && !add_consumer(uprobe, consumer)) {
> +               ret = __register_uprobe(inode, offset, uprobe);
> +               if (ret) {
> +                       uprobe->consumers = NULL;
> +                       __unregister_uprobe(inode, offset, uprobe);
> +               }
> +       }
> +
> +       mutex_unlock(uprobes_hash(inode));
> +       put_uprobe(uprobe);
> +
> +reg_out:
> +       iput(inode);
> +       return ret;
> +} 

So if this function returns an error the caller is responsible for
cleaning up consumer, otherwise we take responsibility.
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