linux-kernel - Re: [RFC][PATCH 2/7] kref: Add kref

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Message-ID: <20161115074703.GK3142@twins.programming.kicks-ass.net>
Date:   Tue, 15 Nov 2016 08:47:03 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Christoph Hellwig <hch@...radead.org>, keescook@...omium.org,
        will.deacon@....com, elena.reshetova@...el.com, arnd@...db.de,
        tglx@...utronix.de, mingo@...nel.org, hpa@...or.com,
        dave@...gbits.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH 2/7] kref: Add kref_read()

On Tue, Nov 15, 2016 at 08:28:55AM +0100, Greg KH wrote:
> On Mon, Nov 14, 2016 at 10:16:55AM -0800, Christoph Hellwig wrote:
> > On Mon, Nov 14, 2016 at 06:39:48PM +0100, Peter Zijlstra wrote:
> > > Since we need to change the implementation, stop exposing internals.
> > > 
> > > Provide kref_read() to read the current reference count; typically
> > > used for debug messages.
> > 
> > Can we just provide a printk specifier for a kref value instead as
> > that is the only valid use case for reading the value?
> 
> Yeah, that would be great as no one should be doing anything
> logic-related based on the kref value.

IIRC there are a few users that WARN_ON() the value with a minimum bound
or somesuch. Those would be left in the cold, but yes I too like the
idea of a printk() format specifier.