Re: [PATCH 3/7] nvme: implement mq_ops->commit_rqs() hook

[Christoph Hellwig]

> +static inline int nvme_next_ring_index(struct nvme_queue *nvmeq, u16 index)
> +{
> +     if (++index == nvmeq->q_depth)
> +             return 0;
> +
> +     return index;
> +}

This is unused now.

Also what about this little cleanup on top?

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 42472bd0cfed..527907aa6903 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -523,22 +523,26 @@ static int nvme_pci_map_queues(struct blk_mq_tag_set *set)
        return 0;
 }
 
-static inline void nvme_write_sq_db(struct nvme_queue *nvmeq)
+/*
+ * Write sq tail if we are asked to, or if the next command would wrap.
+ */
+static inline void nvme_write_sq_db(struct nvme_queue *nvmeq, bool write_sq)
 {
+       if (!write_sq) {
+               u16 next_tail = nvmeq->sq_tail + 1;
+
+               if (next_tail == nvmeq->q_depth)
+                       next_tail = 0;
+               if (next_tail != nvmeq->last_sq_tail)
+                       return;
+       }
+
        if (nvme_dbbuf_update_and_check_event(nvmeq->sq_tail,
                        nvmeq->dbbuf_sq_db, nvmeq->dbbuf_sq_ei))
                writel(nvmeq->sq_tail, nvmeq->q_db);
        nvmeq->last_sq_tail = nvmeq->sq_tail;
 }
 
-static inline int nvme_next_ring_index(struct nvme_queue *nvmeq, u16 index)
-{
-       if (++index == nvmeq->q_depth)
-               return 0;
-
-       return index;
-}
-
 /**
  * nvme_submit_cmd() - Copy a command into a queue and ring the doorbell
  * @nvmeq: The queue to use
@@ -548,24 +552,11 @@ static inline int nvme_next_ring_index(struct nvme_queue 
*nvmeq, u16 index)
 static void nvme_submit_cmd(struct nvme_queue *nvmeq, struct nvme_command *cmd,
                            bool write_sq)
 {
-       u16 next_tail;
-
        spin_lock(&nvmeq->sq_lock);
-
        memcpy(&nvmeq->sq_cmds[nvmeq->sq_tail], cmd, sizeof(*cmd));
-
        if (++nvmeq->sq_tail == nvmeq->q_depth)
                nvmeq->sq_tail = 0;
-
-       next_tail = nvmeq->sq_tail + 1;
-       if (next_tail == nvmeq->q_depth)
-               next_tail = 0;
-
-       /*
-        * Write sq tail if we have to, OR if the next command would wrap
-        */
-       if (write_sq || next_tail == nvmeq->last_sq_tail)
-               nvme_write_sq_db(nvmeq);
+       nvme_write_sq_db(nvmeq, write_sq);
        spin_unlock(&nvmeq->sq_lock);
 }
 
@@ -575,7 +566,7 @@ static void nvme_commit_rqs(struct blk_mq_hw_ctx *hctx)
 
        spin_lock(&nvmeq->sq_lock);
        if (nvmeq->sq_tail != nvmeq->last_sq_tail)
-               nvme_write_sq_db(nvmeq);
+               nvme_write_sq_db(nvmeq, true);
        spin_unlock(&nvmeq->sq_lock);
 }