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| author | Chris Metcalf <cmetcalf@tilera.com> | 2011-06-02 10:19:41 -0400 |
|---|---|---|
| committer | Pekka Enberg <penberg@kernel.org> | 2011-06-03 19:33:49 +0300 |
| commit | d4d84fef6d0366b585b7de13527a0faeca84d9ce (patch) | |
| tree | c67449976f955cff4a2fe8a74affc2dd67c37b7e /include/linux/percpu.h | |
| parent | 55922c9d1b84b89cb946c777fddccb3247e7df2c (diff) | |
| download | linux-d4d84fef6d0366b585b7de13527a0faeca84d9ce.tar.gz | |
slub: always align cpu_slab to honor cmpxchg_double requirement
On an architecture without CMPXCHG_LOCAL but with DEBUG_VM enabled,
the VM_BUG_ON() in __pcpu_double_call_return_bool() will cause an early
panic during boot unless we always align cpu_slab properly.
In principle we could remove the alignment-testing VM_BUG_ON() for
architectures that don't have CMPXCHG_LOCAL, but leaving it in means
that new code will tend not to break x86 even if it is introduced
on another platform, and it's low cost to require alignment.
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Diffstat (limited to 'include/linux/percpu.h')
| -rw-r--r-- | include/linux/percpu.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/percpu.h b/include/linux/percpu.h index 8b97308e65df..9ca008f0c542 100644 --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -259,6 +259,9 @@ extern void __bad_size_call_parameter(void); * Special handling for cmpxchg_double. cmpxchg_double is passed two * percpu variables. The first has to be aligned to a double word * boundary and the second has to follow directly thereafter. + * We enforce this on all architectures even if they don't support + * a double cmpxchg instruction, since it's a cheap requirement, and it + * avoids breaking the requirement for architectures with the instruction. */ #define __pcpu_double_call_return_bool(stem, pcp1, pcp2, ...) \ ({ \ |