[PATCH 4/8] blk-mq: introduce blk_mq_hw_queue_first_cpu() to figure out first cpu

[Ming Lei]

This patch introduces helper of blk_mq_hw_queue_first_cpu() for
figuring out the hctx's first cpu, and code duplication can be
avoided.

Cc: Christian Borntraeger <borntrae...@de.ibm.com>
Cc: Christoph Hellwig <h...@lst.de>
Cc: Stefan Haberland <s...@linux.vnet.ibm.com>
Signed-off-by: Ming Lei <ming....@redhat.com>
---
 block/blk-mq.c | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index a16efa6f2e7f..e3d02af79010 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1336,6 +1336,15 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx 
*hctx)
        hctx_unlock(hctx, srcu_idx);
 }
 
+static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
+{
+       int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
+
+       if (cpu >= nr_cpu_ids)
+               cpu = cpumask_first(hctx->cpumask);
+       return cpu;
+}
+
 /*
  * It'd be great if the workqueue API had a way to pass
  * in a mask and had some smarts for more clever placement.
@@ -1355,14 +1364,7 @@ static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx 
*hctx)
                next_cpu = cpumask_next_and(next_cpu, hctx->cpumask,
                                cpu_online_mask);
                if (next_cpu >= nr_cpu_ids)
-                       next_cpu = cpumask_first_and(hctx->cpumask, 
cpu_online_mask);
-
-               /*
-                * No online CPU is found, so have to make sure hctx->next_cpu
-                * is set correctly for not breaking workqueue.
-                */
-               if (next_cpu >= nr_cpu_ids)
-                       next_cpu = cpumask_first(hctx->cpumask);
+                       next_cpu = blk_mq_first_mapped_cpu(hctx);
                hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
        }
 
@@ -2431,10 +2433,7 @@ static void blk_mq_map_swqueue(struct request_queue *q)
                /*
                 * Initialize batch roundrobin counts
                 */
-               hctx->next_cpu = cpumask_first_and(hctx->cpumask,
-                               cpu_online_mask);
-               if (hctx->next_cpu >= nr_cpu_ids)
-                       hctx->next_cpu = cpumask_first(hctx->cpumask);
+               hctx->next_cpu = blk_mq_first_mapped_cpu(hctx);
                hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
        }
 }
-- 
2.9.5