linux-kernel - Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return functions

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Message-ID: <15137.1504306313@warthog.procyon.org.uk>
Date:   Fri, 01 Sep 2017 23:51:53 +0100
From:   David Howells <dhowells@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     dhowells@...hat.com, linux-afs@...ts.infradead.org,
        linux-fsdevel@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return functions

Peter Zijlstra <peterz@...radead.org> wrote:

> 	if (obj) {
> 	  /* use obj */
> 	  refcount_dec(&obj->refs); /* should never hit 0 */
> 	}

You've missed a bit: We need to tell the gc to run when we reduce the refcount
to 1:

	if (obj) {
		...
		if (refcount_dec_return(&obj->refs) == 1)
			schedule_gc();
	}

David