Messages in this thread Patch in this message | | | From | Rusty Russell <> | Date | Thu, 19 Nov 2009 19:31:25 +1030 | Subject | [PATCH 5/6] cpumask: remove struct cpumask definition when CONFIG_CPUMASK_OFFSTACK=y |
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We're about to change CONFIG_CPUMASK_OFFSTACK so it only allocate nr_cpu_ids bits for all cpumasks. We need to make sure that when CONFIG_CPUMASK_OFFSTACK is set:
1) Noone uses the old bitmap ops, which use NR_CPUS bits (use cpumask_*) 2) Noone uses assignment of struct cpumask (use cpumask_copy) 3) Noone passes a struct cpumask (pass a pointer) 4) Noone declares them on the stack (use cpumask_var_t)
So we finally remove the definition of struct cpumask when CONFIG_CPUMASK_OFFSTACK=y. This means that these usages will hit a compile error the moment that config option is turned on.
Note that it also means you can't declare a static cpumask. You should avoid this anyway (use cpumask_var_t), but there's a deliberately-ugly workaround for special cases, using DECLARE_BITMAP() and to_cpumask().
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> --- include/linux/cpumask.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -10,7 +10,15 @@ #include <linux/threads.h> #include <linux/bitmap.h> +#ifdef CONFIG_CPUMASK_OFFSTACK +/* + * This is never declared, so you can't accidentally create one (see + * cpumask_var_t) or copy them by assignment (see cpumask_copy). + */ +struct cpumask; +#else typedef struct cpumask { DECLARE_BITMAP(bits, NR_CPUS); } cpumask_t; +#endif /* CONFIG_CPUMASK_OFFSTACK */ /** * cpumask_bits - get the bits in a cpumask @@ -19,7 +28,14 @@ typedef struct cpumask { DECLARE_BITMAP( * You should only assume nr_cpu_ids bits of this mask are valid. This is * a macro so it's const-correct. */ +#ifdef CONFIG_CPUMASK_OFFSTACK +static inline unsigned long *cpumask_bits(const struct cpumask *mask) +{ + return (unsigned long *)mask; +} +#else #define cpumask_bits(maskp) ((maskp)->bits) +#endif #if NR_CPUS == 1 #define nr_cpu_ids 1
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