linux-kernel - Re: [thisops uV3 07/18] highmem: Use this_cpu_xx

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Message-ID: <alpine.DEB.2.00.1011301352390.4039@router.home>
Date:	Tue, 30 Nov 2010 13:53:11 -0600 (CST)
From:	Christoph Lameter <cl@...ux.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
cc:	Eric Dumazet <eric.dumazet@...il.com>, akpm@...ux-foundation.org,
	Pekka Enberg <penberg@...helsinki.fi>,
	Catalin Marinas <catalin.marinas@....com>,
	linux-kernel@...r.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Tejun Heo <tj@...nel.org>, linux-mm@...ck.org
Subject: Re: [thisops uV3 07/18] highmem: Use this_cpu_xx_return()
 operations

On Tue, 30 Nov 2010, Peter Zijlstra wrote:

> On Tue, 2010-11-30 at 20:29 +0100, Eric Dumazet wrote:
> >
> > well maybe a single prototype ;)
> >
> > static inline void kmap_atomic_idx_pop(void)
> > {
> > #ifdef CONFIG_DEBUG_HIGHMEM
> >         int idx = __this_cpu_dec_return(__kmap_atomic_idx);
> >         BUG_ON(idx < 0);
> > #else
> >       __this_cpu_dec(__kmap_atomic_idx);
> > #endif
> > }
>
> Right, at least a consistent prototype, the above looks fine to me.

Ok with right spacing this is:

Subject: highmem: Use this_cpu_dec instead of __this_cpu_dec_return if
!DEBUG_HIGHMEM

Signed-off-by: Christoph Lameter <cl@...ux.com>

---
 include/linux/highmem.h |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

Index: linux-2.6/include/linux/highmem.h
===================================================================
--- linux-2.6.orig/include/linux/highmem.h	2010-11-30 13:23:44.000000000 -0600
+++ linux-2.6/include/linux/highmem.h	2010-11-30 13:51:39.000000000 -0600
@@ -95,13 +95,15 @@ static inline int kmap_atomic_idx(void)
 	return __this_cpu_read(__kmap_atomic_idx) - 1;
 }

-static inline int kmap_atomic_idx_pop(void)
+static inline void kmap_atomic_idx_pop(void)
 {
-	int idx = __this_cpu_dec_return(__kmap_atomic_idx);
 #ifdef CONFIG_DEBUG_HIGHMEM
+	int idx = __this_cpu_dec_return(__kmap_atomic_idx);
+
 	BUG_ON(idx < 0);
+#else
+	__this_cpu_dec(__kmap_atomic_idx);
 #endif
-	return idx;
 }

 #endif

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