Commit 1e835278 authored Feb 23, 2008 by Hugh Dickins Committed by Linus Torvalds Feb 23, 2008

percpu: fix DEBUG_PREEMPT per_cpu checking

2.6.25-rc1 percpu changes broke CONFIG_DEBUG_PREEMPT's per_cpu checking
on several architectures. On s390, sparc64 and x86 it's been weakened to
not checking at all; whereas on powerpc64 it's become too strict, issuing
warnings from __raw_get_cpu_var in io_schedule and init_timer for example.

Fix this by weakening powerpc's __my_cpu_offset to use the non-checking
local_paca instead of get_paca (which itself contains such a check);
and strengthening the generic my_cpu_offset to go the old slow way via
smp_processor_id when CONFIG_DEBUG_PREEMPT (debug_smp_processor_id is
where all the knowledge of what's correct when lives).

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Reviewed-by: Mike Travis <travis@sgi.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 3a2d5b70

include/asm-generic/percpu.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -32,6 +32,8 @@ extern unsigned long __per_cpu_offset[NR_CPUS];
		*/
		#ifndef __my_cpu_offset
		#define __my_cpu_offset per_cpu_offset(raw_smp_processor_id())
		#endif
		#ifdef CONFIG_DEBUG_PREEMPT
		#define my_cpu_offset per_cpu_offset(smp_processor_id())
		#else
		#define my_cpu_offset __my_cpu_offset

include/asm-powerpc/percpu.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -13,7 +13,7 @@
		#include <asm/paca.h>

		#define __per_cpu_offset(cpu) (paca[cpu].data_offset)
		#define __my_cpu_offset get_paca()->data_offset
		#define __my_cpu_offset local_paca->data_offset
		#define per_cpu_offset(x) (__per_cpu_offset(x))

		#endif /* CONFIG_SMP */