On 10/30/18 6:49 PM, Sagi Grimberg wrote: > > >> @@ -2342,10 +2346,16 @@ static void blk_mq_map_swqueue(struct request_queue *q) >> >> ctx = per_cpu_ptr(q->queue_ctx, i); >> hctx = blk_mq_map_queue_type(q, 0, i); >> - >> + hctx->type = 0; >> cpumask_set_cpu(i, hctx->cpumask); >> - ctx->index_hw = hctx->nr_ctx; >> + ctx->index_hw[hctx->type] = hctx->nr_ctx; >> hctx->ctxs[hctx->nr_ctx++] = ctx; >> + >> + /* >> + * If the nr_ctx type overflows, we have exceeded the >> + * amount of sw queues we can support. >> + */ >> + BUG_ON(!hctx->nr_ctx); > > Was this added because nr_ctx became short? What was the motivation > for that? save space? structure alignment? Right, I made it smaller to not take up more space after this change. And since it is now smaller, adding a check for wrap seemed like a good idea. > Perhaps this should be mentioned in the change log (as it contradicts > that no functional changes exist in this patch). Or, if this can happen > even when 32bit nr_ctx, it should be a separate small patch? Could happen for any type, but more likely now of course. I'll mention this in the changelog. -- Jens Axboe
