Messages in this thread |  | | | Date | Tue, 29 Sep 2009 01:14:03 +0900 (JST) | | Subject | Re: No more bits in vm_area_struct's vm_flags. | | From | "KAMEZAWA Hiroyuki" <> |
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Hugh Dickins wrote: > On Mon, 28 Sep 2009, KAMEZAWA Hiroyuki wrote: >> >> What I dislike is making vm_flags to be long long ;) > > Why? I'm sorry if my "dislike" sounds too strong.
Every time I see long long in the kernel, my concern is "do I need spinlock to access this for 32bit arch ? is it safe ?". (And it makes binary=>disassemble=>C (by eyes) a bit difficult) Then, I don't like long long personally.
Another reason is some other calls like test_bit() cannot be used against long long. (even if it's not used _now_)
Maybe vm->vm_flags will not require extra locks because it can be protected by bigger lock as mmap_sem. Then, please make it to be long long if its's recommended.
keeping vm_flags to be 32bit may makes vma_merge() ugly. If so, long long is a choice.
Thanks, -Kame
> Hugh >
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