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

From	David Howells <dhowells@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return functions
Date	2017-09-01 23:20 +0200
Message-ID	<ul1w6-288-11@gated-at.bofh.it> (permalink)
References	<ukXiN-7Ew-1@gated-at.bofh.it> <ukWmK-71s-3@gated-at.bofh.it> <ukWmL-71s-37@gated-at.bofh.it> <ukXiN-7Ew-1@gated-at.bofh.it>
Organization	Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903

Show all headers | View raw

Peter Zijlstra <peterz@infradead.org> wrote:

> > 	unsigned int refcount_dec_return(refcount_t *r);
> > 	unsigned int refcount_inc_return(refcount_t *r);
> > 
> 
> I'm not immediately seeing how wanting 1 to mean unused leads to
> requiring these two functions.

Did you read the other other part of the description?

	Further, both functions can be used to accurately trace the refcount
	(refcount_inc() followed by refcount_read() can't be considered
	accurate).

> If you'll remember, I did that for inode_count and only needed
> dec_unless().

I don't remember.  inode_count?  I can't find such a thing - did you mean
i_count?  I don't find anything matching "dec_unless.*i_count" either.

David

Thread

[RFC PATCH 02/11] refcount: Implement inc/decrement-and-return  functions David Howells <dhowells@redhat.com> - 2017-09-01 17:50 +0200
  Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return  functions Peter Zijlstra <peterz@infradead.org> - 2017-09-01 18:50 +0200
    Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return functions David Howells <dhowells@redhat.com> - 2017-09-01 23:20 +0200
      Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return  functions Peter Zijlstra <peterz@infradead.org> - 2017-09-02 00:00 +0200
        Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return  functions Peter Zijlstra <peterz@infradead.org> - 2017-09-02 00:10 +0200
        Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return functions David Howells <dhowells@redhat.com> - 2017-09-02 01:00 +0200
          Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return  functions Peter Zijlstra <peterz@infradead.org> - 2017-09-04 09:40 +0200
  Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return  functions Christoph Hellwig <hch@infradead.org> - 2017-09-04 17:40 +0200
    Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return functions David Howells <dhowells@redhat.com> - 2017-09-04 18:10 +0200
      Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return  functions Christoph Hellwig <hch@infradead.org> - 2017-09-05 08:50 +0200

csiph-web