From 0d0b7d427987f6e98b6f32e84ee071f36f85c3d4 Mon Sep 17 00:00:00 2001 From: Jose Alonso Date: Tue, 28 Jan 2014 08:09:46 -0700 Subject: [PATCH] blk-mq: for_each_* macro correctness I observed that there are for_each macros that do an extra memory access beyond the defined area. Normally this does not cause problems. But, this can cause exceptions. For example: if the area is allocated at the end of a page and the next page is not accessible. For correctness, I suggest changing the arguments of the 'for loop' like others 'for_each' do in the kernel. Signed-off-by: Jose Alonso Signed-off-by: Jens Axboe --- include/linux/blk-mq.h | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 851d34b7ac26..161b23105b1e 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -158,16 +158,16 @@ static inline struct request *blk_mq_tag_to_rq(struct blk_mq_hw_ctx *hctx, } #define queue_for_each_hw_ctx(q, hctx, i) \ - for ((i) = 0, hctx = (q)->queue_hw_ctx[0]; \ - (i) < (q)->nr_hw_queues; (i)++, hctx = (q)->queue_hw_ctx[i]) + for ((i) = 0; (i) < (q)->nr_hw_queues && \ + ({ hctx = (q)->queue_hw_ctx[i]; 1; }); (i)++) #define queue_for_each_ctx(q, ctx, i) \ - for ((i) = 0, ctx = per_cpu_ptr((q)->queue_ctx, 0); \ - (i) < (q)->nr_queues; (i)++, ctx = per_cpu_ptr(q->queue_ctx, (i))) + for ((i) = 0; (i) < (q)->nr_queues && \ + ({ ctx = per_cpu_ptr((q)->queue_ctx, (i)); 1; }); (i)++) #define hctx_for_each_ctx(hctx, ctx, i) \ - for ((i) = 0, ctx = (hctx)->ctxs[0]; \ - (i) < (hctx)->nr_ctx; (i)++, ctx = (hctx)->ctxs[(i)]) + for ((i) = 0; (i) < (hctx)->nr_ctx && \ + ({ ctx = (hctx)->ctxs[(i)]; 1; }); (i)++) #define blk_ctx_sum(q, sum) \ ({ \ -- 2.39.5