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Date: Tue, 2 Apr 2013 12:27:38 -0400
From: "Theodore Ts'o" <tytso@mit.edu>
To: Kent Overstreet <koverstreet@google.com>
Cc: linux-kernel@vger.kernel.org, linux-aio@kvack.org,
        akpm@linux-foundation.org, Zach Brown <zab@redhat.com>,
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        Jeff Moyer <jmoyer@redhat.com>, Al Viro <viro@zeniv.linux.org.uk>,
        Benjamin LaHaise <bcrl@kvack.org>
Subject: Re: [PATCH 23/33] generic dynamic per cpu refcounting
Message-ID: <20130402162738.GG31577@thunk.org>
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Reviewed-by: "Theodore Ts'o" <tytso@mit.edu>

> +		v = atomic64_add_return(1 + (1ULL << PCPU_COUNT_BITS),
> +					&ref->count);
> +
> +		if (!(v >> PCPU_COUNT_BITS) &&
> +		    REF_STATUS(pcpu_count) == PCPU_REF_NONE && alloc)
> +			percpu_ref_alloc(ref, pcpu_count);

This assumes that the kernel is compiled with -fno-strict-overflow.
Which we do, and this is not the only place int the kernel where we
depend on this, so while I was nervous before, I'm okay with it now.
Could we at least have a comment saying that we're depending on
-fno-strict-overflow, though?


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