From: Christoph Lameter <cl@linux.com>
To: Tejun Heo <tj@kernel.org>
Cc: Dmitry Antipov <dmitry.antipov@linaro.org>,
Rusty Russell <rusty@rustcorp.com.au>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
patches@linaro.org, linaro-dev@lists.linaro.org
Subject: Re: [PATCH 1/3] percpu: use ZERO_SIZE_PTR / ZERO_OR_NULL_PTR
Date: Mon, 30 Jan 2012 11:35:29 -0600 (CST) [thread overview]
Message-ID: <alpine.DEB.2.00.1201301134090.28693@router.home> (raw)
In-Reply-To: <20120130173311.GE3355@google.com>
On Mon, 30 Jan 2012, Tejun Heo wrote:
> I'm pretty sure it never gives out NULL for a dynamic allocation. The
> base might be mapped to zero but we're guaranteed to have some static
> percpu areas there and IIRC the percpu addresses aren't supposed to
> wrap.
True but there is a check for a NULL pointer on free. So a NULL pointer
currently has the semantics of being an unallocated per cpu structure.
If the allocator returns NULL by accident then we cannot free the per cpu
allocation anymore.
next prev parent reply other threads:[~2012-01-30 17:35 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-30 8:37 [PATCH 1/3] percpu: use ZERO_SIZE_PTR / ZERO_OR_NULL_PTR Dmitry Antipov
2012-01-30 16:15 ` Christoph Lameter
2012-01-30 17:15 ` Tejun Heo
2012-01-30 17:19 ` Tejun Heo
2012-01-30 17:22 ` Christoph Lameter
2012-01-30 17:33 ` Tejun Heo
2012-01-30 17:35 ` Christoph Lameter [this message]
2012-01-30 17:22 ` Christoph Lameter
2012-01-30 17:42 ` Tejun Heo
2012-01-30 17:52 ` Christoph Lameter
2012-01-30 17:54 ` Tejun Heo
2012-01-30 17:58 ` Christoph Lameter
2012-01-30 18:02 ` Tejun Heo
2012-01-30 18:12 ` Christoph Lameter
2012-01-30 18:16 ` Tejun Heo
2012-01-31 4:48 ` Rusty Russell
2012-01-30 18:13 ` Tejun Heo
2012-01-30 18:15 ` Christoph Lameter
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