On 11/9/2018 8:13 PM, Pavel Tatashin wrote:
On 18-11-05 13:20:01, Alexander Duyck wrote:+static unsigned long __next_pfn_valid_range(unsigned long *i, + unsigned long end_pfn) { - if (!pfn_valid_within(pfn)) - return false; - if (!(pfn & (pageblock_nr_pages - 1)) && !pfn_valid(pfn)) - return false; - return true; + unsigned long pfn = *i; + unsigned long count; + + while (pfn < end_pfn) { + unsigned long t = ALIGN(pfn + 1, pageblock_nr_pages); + unsigned long pageblock_pfn = min(t, end_pfn); + +#ifndef CONFIG_HOLES_IN_ZONE + count = pageblock_pfn - pfn; + pfn = pageblock_pfn; + if (!pfn_valid(pfn)) + continue; +#else + for (count = 0; pfn < pageblock_pfn; pfn++) { + if (pfn_valid_within(pfn)) { + count++; + continue; + } + + if (count) + break; + } + + if (!count) + continue; +#endif + *i = pfn; + return count; + } + + return 0; }+#define for_each_deferred_pfn_valid_range(i, start_pfn, end_pfn, pfn, count) \+ for (i = (start_pfn), \ + count = __next_pfn_valid_range(&i, (end_pfn)); \ + count && ({ pfn = i - count; 1; }); \ + count = __next_pfn_valid_range(&i, (end_pfn)))Can this be improved somehow? It took me a while to understand this piece of code. i is actually end of block, and not an index by PFN, ({pfn = i - count; 1;}) is simply hard to parse. Why can't we make __next_pfn_valid_range() to return both end and a start of a block?
One thing I could do is flip the direction and work from the end to the start. If I did that then 'i' and 'pfn' would be the same value and I wouldn't have to do the subtraction. If that works for you I could probably do that and it may actually be more efficient.
Otherwise I could probably pass pfn as a reference, and compute it in the case where count is non-zero.
The rest is good: Reviewed-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> Thank you, Pasha
