linux-kernel - Re: [PATCHv2 2/3] kernel: add support for live patching

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Message-ID: <20141120164851.GB13785@cerebellum.variantweb.net>
Date:	Thu, 20 Nov 2014 10:48:51 -0600
From:	Seth Jennings <sjenning@...hat.com>
To:	Josh Poimboeuf <jpoimboe@...hat.com>
Cc:	Jiri Kosina <jkosina@...e.cz>, Vojtech Pavlik <vojtech@...e.cz>,
	Steven Rostedt <rostedt@...dmis.org>,
	Petr Mladek <pmladek@...e.cz>, Miroslav Benes <mbenes@...e.cz>,
	Christoph Hellwig <hch@...radead.org>,
	Greg KH <gregkh@...uxfoundation.org>,
	Andy Lutomirski <luto@...capital.net>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	live-patching@...r.kernel.org, x86@...nel.org, kpatch@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 2/3] kernel: add support for live patching

On Thu, Nov 20, 2014 at 09:19:54AM -0600, Josh Poimboeuf wrote:
> On Sun, Nov 16, 2014 at 07:29:23PM -0600, Seth Jennings wrote:
> > +static int lpc_module_notify(struct notifier_block *nb, unsigned long action,
> > +			    void *data)
> > +{
> > +	struct module *mod = data;
> > +	struct lpc_patch *patch;
> > +	struct lpc_object *obj;
> > +
> > +	mutex_lock(&lpc_mutex);
> > +
> > +	if (action != MODULE_STATE_COMING && action != MODULE_STATE_GOING)
> > +		goto out;
> 
> I think we can get the mutex here instead of above so it doesn't block
> other module actions (and then you can also get rid of the "out" label).

Sure.

Thanks,
Seth

> 
> > +
> > +	list_for_each_entry(patch, &lpc_patches, list) {
> > +		if (patch->state == LPC_DISABLED)
> > +			continue;
> > +		list_for_each_entry(obj, &patch->objs, list) {
> > +			if (strcmp(obj->name, mod->name))
> > +				continue;
> > +			if (action == MODULE_STATE_COMING) {
> > +				obj->mod = mod;
> > +				lpc_module_notify_coming(patch->mod, obj);
> > +			} else /* MODULE_STATE_GOING */
> > +				lpc_module_notify_going(patch->mod, obj);
> > +			break;
> > +		}
> > +	}
> > +out:
> > +	mutex_unlock(&lpc_mutex);
> > +	return 0;
> > +}
> 
> -- 
> Josh
> --
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