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 <joalonsof@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 851d34b7..161b231 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -158,16 +158,16 @@
}
#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) \
({ \