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Re: [RFC] Design + prototype: Multiple handler sets per probe address
- From: Ananth N Mavinakayanahalli <amavin at redhat dot com>
- To: William Cohen <wcohen at redhat dot com>
- Cc: systemtap at sources dot redhat dot com
- Date: Fri, 01 Apr 2005 17:51:58 -0500
- Subject: Re: [RFC] Design + prototype: Multiple handler sets per probe address
- References: <424D5BF4.3070601@redhat.com> <424DC555.6060100@redhat.com>
William Cohen wrote:
Ananth N Mavinakayanahalli wrote:
Hi,
Here is a design to support "Mulitple handler sets per address". I
have also put in the i386 implementation based on this design.
Some notes:
- The interfaces to register, unregister, define handlers all remain
the same.
- A kprobe and jprobe cannot co-exist at the same location. (Ideas are
welcome on how to support this).
I have minimally tested the patch and it works(tm).
Please let me know your thoughts on the design. I'd also appreciate if
you could test the patch (diffed against 2.6.12-rc1-mm3) and provide
feedback.
Thanks,
Ananth
I have been working on some simple testing to exercises the multiple
probes. It checks to make sure that probes are inserted and deleted as
expected. It has three probes at location.
I appologize for the verbose output. I have also attached output of the
test results. There are some warning about allocating sleeping function.
The warning appears only in one of the eight runs. Will investigate
this. A GFP_KERNEL/GFP_ATOMIC issue, probably - but if so, why only in
one of the eight runs? Beats me!
It appears to be inserting and removing probes as expected.
Good to hear that!
It seems like it would be useful to have unregister_kprobe() return
whether the operation was successful or not. Be able to catch cases were
code attempts to remove a probe twice.
Changing the existing interface :-) But I suppose users who don't care
about the return code may as well ignore it.
Thanks,
Ananth