nvme-pci: remove nvmeq->tags

There is no real need to have a pointer to the tagset in
struct nvme_queue, as we only need it in a single place, and that place
can derive the used tagset from the device and qid trivially.  This
fixes a problem with stale pointer exposure when tagsets are reset,
and also shrinks the nvme_queue structure.  It also matches what most
other transports have done since day 1.

Reported-by: Edmund Nadolski <edmund.nadolski@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 365a2dd..da392b5 100644 (file)
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -167,7 +167,6 @@ struct nvme_queue {
         /* only used for poll queues: */
        spinlock_t cq_poll_lock ____cacheline_aligned_in_smp;
        volatile struct nvme_completion *cqes;
-       struct blk_mq_tags **tags;
        dma_addr_t sq_dma_addr;
        dma_addr_t cq_dma_addr;
        u32 __iomem *q_db;
@@ -376,29 +375,17 @@ static int nvme_admin_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
 
        WARN_ON(hctx_idx != 0);
        WARN_ON(dev->admin_tagset.tags[0] != hctx->tags);
-       WARN_ON(nvmeq->tags);
 
        hctx->driver_data = nvmeq;
-       nvmeq->tags = &dev->admin_tagset.tags[0];
        return 0;
 }
 
-static void nvme_admin_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
-{
-       struct nvme_queue *nvmeq = hctx->driver_data;
-
-       nvmeq->tags = NULL;
-}
-
 static int nvme_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
                          unsigned int hctx_idx)
 {
        struct nvme_dev *dev = data;
        struct nvme_queue *nvmeq = &dev->queues[hctx_idx + 1];
 
-       if (!nvmeq->tags)
-               nvmeq->tags = &dev->tagset.tags[hctx_idx];
-
        WARN_ON(dev->tagset.tags[hctx_idx] != hctx->tags);
        hctx->driver_data = nvmeq;
        return 0;
@@ -948,6 +935,13 @@ static inline void nvme_ring_cq_doorbell(struct nvme_queue *nvmeq)
                writel(head, nvmeq->q_db + nvmeq->dev->db_stride);
 }
 
+static inline struct blk_mq_tags *nvme_queue_tagset(struct nvme_queue *nvmeq)
+{
+       if (!nvmeq->qid)
+               return nvmeq->dev->admin_tagset.tags[0];
+       return nvmeq->dev->tagset.tags[nvmeq->qid - 1];
+}
+
 static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx)
 {
        volatile struct nvme_completion *cqe = &nvmeq->cqes[idx];
@@ -972,7 +966,7 @@ static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx)
                return;
        }
 
-       req = blk_mq_tag_to_rq(*nvmeq->tags, cqe->command_id);
+       req = blk_mq_tag_to_rq(nvme_queue_tagset(nvmeq), cqe->command_id);
        trace_nvme_sq(req, cqe->sq_head, nvmeq->sq_tail);
        nvme_end_request(req, cqe->status, cqe->result);
 }
@@ -1572,7 +1566,6 @@ static const struct blk_mq_ops nvme_mq_admin_ops = {
        .queue_rq       = nvme_queue_rq,
        .complete       = nvme_pci_complete_rq,
        .init_hctx      = nvme_admin_init_hctx,
-       .exit_hctx      = nvme_admin_exit_hctx,
        .init_request   = nvme_init_request,
        .timeout        = nvme_timeout,
 };