Messages in this thread | | | Date | Tue, 26 Aug 2008 09:51:46 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [Bug #11342] Linux 2.6.27-rc3: kernel BUG at mm/vmalloc.c - bisected |
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On Tue, 26 Aug 2008, Yinghai Lu wrote: > > wonder if could use "unsigned long *" directly.
I would actually suggest something like this:
- we continue to have a magic "cpumask_t".
- we do different cases for big and small NR_CPUS:
#if NR_CPUS <= BITS_PER_LONG
/* * Make it an array - that way passing it as an argument will * always pass it as a pointer! */ typedef unsigned long cpumask_t[1];
static inline void create_cpumask(cpumask_t *p) { *p = 0; } static inline void free_cpumask(cpumask_t *p) { }
#else
typedef unsigned long *cpumask_t;
static inline void create_cpumask(cpumask_t *p) { *p = kcalloc(..); }
static inline void free_cpumask(cpumask_t *p) { kfree(*p); }
#endif
and now after you do this, you can just do something like
cpumask_t mycpu;
create_cpumask(&mycpu); .. free_cpumask(&mycpu);
and in between, you can use 'cpumask' as a pointer, because even when it is an array directly allocated on the stack, the array can always degenerate into a pointer by C type rules!
And for the small-NR_CPUS case there is zero overhead.
Linus
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