percpu: fix DEBUG_PREEMPT per_cpu checking
authorHugh Dickins <hugh@veritas.com>
Sat, 23 Feb 2008 19:40:17 +0000 (19:40 +0000)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Sat, 23 Feb 2008 20:09:28 +0000 (12:09 -0800)
commit1e8352784abaedb424e63fa700e93e6c1307785f
treeeb7ba51fa40e209ed2a1636b3404cca58141bed1
parent3a2d5b700132f35401f1d9e22fe3c2cab02c2549
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>
include/asm-generic/percpu.h
include/asm-powerpc/percpu.h