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SubjectRe: [PATCH] utrace: remove exports
On Mon, Apr 30, 2007 at 10:12:44AM +0100, Christoph Hellwig wrote:
> On Sun, Apr 29, 2007 at 09:02:32PM -0700, Roland McGrath wrote:
> > > EXPORT_SYMBOL_GPL(utrace_attach);
> > >
> > > There is not modular user of this, so this and the other utrace_
> > > functions should not be exported. Nor do I think that exporting
> > > such a low-level process control is nessecary a good idea, but
> > > we'll have to evaluate that if patches to add users show up.
> >
> > If you remove the exports, just throw the whole thing away.
> > The reason utrace exists is to be used by modules.
>
> used != used by modules. Even without things exported you can use
> things in the kernel. Once we have a valid modular use case we can
> add exports.

Christoph, it's at
http://people.redhat.com/roland/utrace/crash-suspend.c

The file crash-suspend.c is a simple example of a loadable kernel module
using the new infrastructure. It implements the old GNU feature of doing a
job suspend on crash, so you can attach a debugger right then instead of
just looking at the core file afterwards. Try for example:
$ sudo /sbin/insmod crash-suspend.ko pid=$$
to load the module and attach it to your shell. It then attaches to any
children of your shell. Now run something that crashes and would
ordinarily dump core--you can just run cat or sleep and hit ^\ to crash it
with a SIGQUIT. See it suspend. Try "jobs -l" and see it stopped with a
non-stop signal. If you resume it with "fg" it will go ahead and dump
core. Or, you can attach a debugger like gdb first, and then debug it.



Most certainly, it should be included into utrace patchset to pin some
exports.

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