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Subject[PATCH 5.5 379/399] nvme-pci: remove nvmeq->tags
Date
From: Christoph Hellwig <hch@lst.de>

[ Upstream commit cfa27356f835dc7755192e7b941d4f4851acbcc7 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/nvme/host/pci.c | 23 ++++++++---------------
1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 365a2ddbeaa76..da392b50f73e7 100644
--- 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,
};
--
2.20.1


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