Update pcpu_alloc_area() so that it can skip unpopulated areas if the new parameter @pop_only is true. This is implemented by a new function, pcpu_fit_in_area(), which determines the amount of head padding considering the alignment and populated state.
@pop_only is currently always false but this will be used to implement atomic allocation. Signed-off-by: Tejun Heo <[email protected]> --- mm/percpu.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 58 insertions(+), 7 deletions(-) diff --git a/mm/percpu.c b/mm/percpu.c index 507afc0..7f2858c 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -400,10 +400,60 @@ out_unlock: } /** + * pcpu_fit_in_area - try to fit the requested allocation in a candidate area + * @chunk: chunk the candidate area belongs to + * @off: the offset to the start of the candidate area + * @this_size: the size of the candidate area + * @size: the size of the target allocation + * @align: the alignment of the target allocation + * @pop_only: only allocate from already populated region + * + * We're trying to allocate @size bytes aligned at @align. @chunk's area + * at @off sized @this_size is a candidate. This function determines + * whether the target allocation fits in the candidate area and returns the + * number of bytes to pad after @off. If the target area doesn't fit, -1 + * is returned. + * + * If @pop_only is %true, this function only considers the already + * populated part of the candidate area. + */ +static int pcpu_fit_in_area(struct pcpu_chunk *chunk, int off, int this_size, + int size, int align, bool pop_only) +{ + int cand_off = off; + + while (true) { + int head = ALIGN(cand_off, align) - off; + int page_start, page_end, rs, re; + + if (this_size < head + size) + return -1; + + if (!pop_only) + return head; + + /* + * If the first unpopulated page is beyond the end of the + * allocation, the whole allocation is populated; + * otherwise, retry from the end of the unpopulated area. + */ + page_start = PFN_DOWN(head + off); + page_end = PFN_UP(head + off + size); + + rs = page_start; + pcpu_next_unpop(chunk, &rs, &re, PFN_UP(off + this_size)); + if (rs >= page_end) + return head; + cand_off = re * PAGE_SIZE; + } +} + +/** * pcpu_alloc_area - allocate area from a pcpu_chunk * @chunk: chunk of interest * @size: wanted size in bytes * @align: wanted align + * @pop_only: allocate only from the populated area * * Try to allocate @size bytes area aligned at @align from @chunk. * Note that this function only allocates the offset. It doesn't @@ -418,7 +468,8 @@ out_unlock: * Allocated offset in @chunk on success, -1 if no matching area is * found. */ -static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align) +static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align, + bool pop_only) { int oslot = pcpu_chunk_slot(chunk); int max_contig = 0; @@ -434,11 +485,11 @@ static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align) if (off & 1) continue; - /* extra for alignment requirement */ - head = ALIGN(off, align) - off; - this_size = (p[1] & ~1) - off; - if (this_size < head + size) { + + head = pcpu_fit_in_area(chunk, off, this_size, size, align, + pop_only); + if (head < 0) { if (!seen_free) { chunk->first_free = i; seen_free = true; @@ -730,7 +781,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved) spin_lock_irqsave(&pcpu_lock, flags); } - off = pcpu_alloc_area(chunk, size, align); + off = pcpu_alloc_area(chunk, size, align, false); if (off >= 0) goto area_found; @@ -761,7 +812,7 @@ restart: goto restart; } - off = pcpu_alloc_area(chunk, size, align); + off = pcpu_alloc_area(chunk, size, align, false); if (off >= 0) goto area_found; } -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
