On Wed, 6 Apr 2011 17:09:04 +0200, "Roland Vossen" <[email protected]> wrote:
> Hello Rusty,
>
> I would like to make a change to module.c and noticed with 'git blame'
> that you were the last person who touched these specific lines in module.c:
>
> http://lxr.linux.no/#linux+v2.6.38/kernel/module.c#L2792
>
> ===== Corresponding commit for your reference:
>
> commit 811d66a0e1e99902d365497eec7884113a2665bd
> Author: Rusty Russell <[email protected]>
> Date: Thu Aug 5 12:59:12 2010 -0600
>
> module: group post-relocation functions into post_relocation()
>
> This simply hoists more code out of load_module; we also put the
> identification of the extable and dynamic debug table in with the
> others in find_module_sections().
>
> We move the taint check to the actual add/remove of the dynamic debug
> info: this is certain (find_module_sections is too early).
>
> Signed-off-by: Rusty Russell <[email protected]>
> Cc: Yehuda Sadeh <[email protected]>
>
> ==============
>
>
> Can you tell me if the following proposed code change in module.c is ok
> with you:
>
> /* This has to be done once we're sure module name is unique. */
> if (!mod->taints || mod->taints == (1U << TAINT_CRAP))
> dynamic_debug_setup(info.debug, info.num_debug);
>
> Thanks, Roland.
>
>
> -------- Original Message --------
> Subject: Re: Why is dynamic debug disabled for staging drivers ?
> Date: Wed, 6 Apr 2011 07:13:29 -0700
> From: Greg KH <[email protected]>
> To: Roland Vossen <[email protected]>
> CC: [email protected] <[email protected]>
>
> On Wed, Apr 06, 2011 at 03:54:37PM +0200, Roland Vossen wrote:
> > Hi,
> >
> > I want to replace the proprietary logging mechanism in brcm80211
> > with a Linux mechanism. 'Dynamic debug' seemed to be a good fit.
> > But, to my disappointment, I discovered that dynamic debugging is
> > not supported for drivers from the staging dir:
> >
> > - staging drivers are marked tainted (ref:
> > http://lxr.linux.no/#linux+v2.6.38/kernel/module.c#L2417)
> >
> > - subsequently tainted drivers don't get dynamic debug goodies (ref:
> > http://lxr.linux.no/#linux+v2.6.38/kernel/module.c#L2792)
> >
> > I wonder if this is intentional behavior. Does anybody know ?
>
> Ah, no it isn't. I didn't realize that tainted modules didn't get
> dynamic debug stuff, that's not nice. I'd be glad to take a fix that
> allows drivers tainted with the TAINT_CRAP flag to be able to use
> dynamic debug.
>
> In looking at that check, it probably can be fixed to just make sure
> that the module name is unique (i.e. only a specific taint flag check)
> which is the real goal of that check in module.c.
That's a red herring. I think it was originally to do with avoiding
hooks for proprietary modules, but it'd take some serious archeology to
find that discussion.
(BTW, is there a simple way of doing a git blame on an older version of
a particular file, when the first git blame refers to a refactoring
patch and you want to dig deeper?)
But a slightly neater change would seem to be:
/* If tainted for any reason other than staging, don't touch it... */
if ((mod->taints & ~(1U << TAINT_CRAP) == 0)
dynamic_debug_setup(info.debug, info.num_debug);
Thanks,
Rusty.
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