Re: [PATCH -mm] kprobes: kretprobe user entry-handler (updated)

[Andrew Morton <akpm@linux-foundation.org>]

On Sat, 26 Jan 2008 23:52:48 +0530 Abhishek Sagar <sagar.abhishek@gmail.com> wrote:

> This is a repost of a patch which was reviewed earlier at:
> http://lkml.org/lkml/2007/11/13/58 (thanks to Jim Keniston and Srinivasa for their review comments). This provides support to add an optional user defined callback to be run at function entry of a kretprobe'd function. It also modifies the kprobe smoke tests to include an entry-handler during the kretprobe sanity test.
> 

Neither the changelog nor the newly-added documentation explain why Linux
needs this feature.  What will it be used for??


> +1.3.2 Kretprobe entry-handler
> +
> +Kretprobes also provides an optional user-specified handler which runs

I think "caller-specified" would be a better term here.  Generally "user"
refers to Aunt Tillie sitting at the keyboard.

> +/* Timestamp function entry. */
> +static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
> +{
> +	struct my_data *data;
> +
> +	if(!current->mm)
> +		return 1; /* skip kernel threads */

gargh, what's happened to checkpatch lately?  It failed to notice the
missing space.