linux-kernel - Re: [PATCH v3 2/2] livepatch: force transition process to finish

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Date:   Fri, 3 Nov 2017 09:07:24 +0100 (CET)
From:   Miroslav Benes <mbenes@...e.cz>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
cc:     jeyu@...nel.org, jikos@...nel.org, pmladek@...e.com,
        lpechacek@...e.cz, pavel@....cz, live-patching@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/2] livepatch: force transition process to finish

On Thu, 2 Nov 2017, Josh Poimboeuf wrote:

> On Tue, Oct 31, 2017 at 12:48:53PM +0100, Miroslav Benes wrote:
> > If a task sleeps in a set of patched functions uninterruptedly, it could
> > block the whole transition process indefinitely.  Thus it may be useful
> > to clear its TIF_PATCH_PENDING to allow the process to finish.
> 
> The phrase "transition process" (here and in the patch title) confused
> me a little bit, since elsewhere we just call it "transition".

Ok.
 
> > +static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr,
> > +			   const char *buf, size_t count)
> > +{
> > +	int ret;
> > +	bool val;
> > +
> > +	/*
> > +	 * klp_mutex lock is not grabbed here intentionally. It is not really
> > +	 * needed. The race window is harmless and grabbing the lock would only
> > +	 * hold the action back.
> > +	 */
> > +	if (!klp_transition_patch)
> > +		return -EINVAL;
> > +
> > +	ret = kstrtobool(buf, &val);
> > +	if (ret)
> > +		return ret;
> > +
> > +	if (val)
> > +		klp_force_transitions();
> 
> The plural "transitions" is inconsistent with the rest of the code,
> which uses it in the singular.  How about klp_force_transition() or
> klp_force()?

klp_force_transition() it is.

Miroslav