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Date: Mon, 21 Nov 2016 10:02:23 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: "Reshetova, Elena" <elena.reshetova@intel.com>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
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Subject: Re: [RFC][PATCH 7/7] kref: Implement using refcount_t
Message-ID: <20161121090223.GE3102@twins.programming.kicks-ass.net>
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On Mon, Nov 21, 2016 at 04:44:28PM +0800, Boqun Feng wrote:
> On Fri, Nov 18, 2016 at 12:37:18PM +0100, Peter Zijlstra wrote:
> [snip]
> > +
> > +/*
> > + * Similar to atomic_inc(), will saturate at UINT_MAX and WARN.
> > + *
> > + * Provides no memory ordering, it is assumed the caller already has a
> > + * reference on the object, will WARN when this is not so.
> > + */
> > +static inline void refcount_inc(refcount_t *r)
> > +{
> > +	unsigned int old, new, val = atomic_read(&r->refs);
> > +
> > +	for (;;) {
> > +		WARN(!val, "refcount_t: increment on 0; use-after-free.\n");
> > +
> 
> Do we want to put the address of @r into the WARN information? Which
> could help us locate the problematic object quickly.

I explicitly didn't do that because printing kernel addresses is
generally frowned upon. Also, random heap addresses are just that,
random. In most cases the backtrace is more informative.