Messages in this thread | | | Date | Thu, 31 Jul 2008 09:43:59 +0300 | From | Avi Kivity <> | Subject | Re: [PATCH 1/2] Export get_user_pages_fast |
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Andrew Morton wrote: > That is how it is presently implemented. > >
Cool.
> #ifdef CONFIG_HAVE_GET_USER_PAGES_FAST > /* > * get_user_pages_fast provides equivalent functionality to get_user_pages, > * operating on current and current->mm (force=0 and doesn't return any vmas). > * > * get_user_pages_fast may take mmap_sem and page tables, so no assumptions > * can be made about locking. get_user_pages_fast is to be implemented in a > * way that is advantageous (vs get_user_pages()) when the user memory area is > * already faulted in and present in ptes. However if the pages have to be > * faulted in, it may turn out to be slightly slower). > */ > int get_user_pages_fast(unsigned long start, int nr_pages, int write, > struct page **pages); > > #else > /* > * Should probably be moved to asm-generic, and architectures can include it if > * they don't implement their own get_user_pages_fast. > */ > #define get_user_pages_fast(start, nr_pages, write, pages) \ > ({ \ > struct mm_struct *mm = current->mm; \ > int ret; \ > \ > down_read(&mm->mmap_sem); \ > ret = get_user_pages(current, mm, start, nr_pages, \ > write, 0, pages, NULL); \ > up_read(&mm->mmap_sem); \ > \ > ret; \ > }) > #endif > >
Surprised. Why not an out-of-line function? Would eliminate the present discussion as well.
-- Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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