From 1f3d29bdca645edd5a623639604328b8ec2193d6 Mon Sep 17 00:00:00 2001 From: Nilay Shroff Date: Mon, 13 Jul 2026 17:24:16 +0530 Subject: [PATCH] nvme: add context annotations for nvme_queue::sq_lock nvme_queue::sq_tail, nvme_queue::last_sq_tail and nvme_queue::sq_cmds are protected by nvme_queue::sq_lock. Annotate each field with __guarded_by(&sq_lock) and annotate helpers that access them with __must_hold(&sq_lock) so that Clang's context analysis can validate the locking requirements. Access to nvme_queue::sq_tail used solely for tracing is annotated with data_race(), as they only require a lockless snapshot of the value. nvme_init_queue() initializes nvme_queue::sq_tail and nvme_queue::last_sq_tail before the queue is published and thus do not require nvme_queue::sq_lock protection. So annotate nvme_init_queue() with context_unsafe() to suppress false positive context analyzer warning. nvme_free_queue() operate on queues which are no longer reachable, and therefore do not require nvme_queue::sq_lock protection. Similarly, nvme_alloc_sq_cmds() allocates memory for nvme_queue::sq_cmds for the queue which is not yet published or in use and hence it's safe to annotate all these helpers using context_unsafe. Reviewed-by: Christoph Hellwig Signed-off-by: Nilay Shroff Signed-off-by: Keith Busch --- drivers/nvme/host/pci.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 8c6d169f2c38..0bce364c7874 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -366,7 +366,8 @@ struct nvme_queue { struct nvme_dev *dev; struct nvme_descriptor_pools descriptor_pools; spinlock_t sq_lock; - void *sq_cmds; + void *sq_cmds + __guarded_by(&sq_lock); /* only used for poll queues: */ spinlock_t cq_poll_lock ____cacheline_aligned_in_smp; struct nvme_completion *cqes; @@ -375,9 +376,11 @@ struct nvme_queue { u32 __iomem *q_db; u32 q_depth; u16 cq_vector; - u16 sq_tail; - u16 last_sq_tail; u16 cq_head; + u16 sq_tail + __guarded_by(&sq_lock); + u16 last_sq_tail + __guarded_by(&sq_lock); u16 qid; u8 cq_phase; u8 sqes; @@ -716,6 +719,7 @@ static void nvme_pci_map_queues(struct blk_mq_tag_set *set) * 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) + __must_hold(&nvmeq->sq_lock) { if (!write_sq) { u16 next_tail = nvmeq->sq_tail + 1; @@ -734,6 +738,7 @@ static inline void nvme_write_sq_db(struct nvme_queue *nvmeq, bool write_sq) static inline void nvme_sq_copy_cmd(struct nvme_queue *nvmeq, struct nvme_command *cmd) + __must_hold(&nvmeq->sq_lock) { memcpy(nvmeq->sq_cmds + (nvmeq->sq_tail << nvmeq->sqes), absolute_pointer(cmd), sizeof(*cmd)); @@ -1586,7 +1591,12 @@ static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, return; } - trace_nvme_sq(req, cqe->sq_head, nvmeq->sq_tail); + /* + * Tracing only; annotate a lockless snapshot of nvmeq->sq_tail using + * data_race(). This would also help suppress context analysis warning + * while accessing nvmeq->sq_tail without acquiring ->sq_lock. + */ + trace_nvme_sq(req, cqe->sq_head, data_race(nvmeq->sq_tail)); if (!nvme_try_complete_req(req, cqe->status, cqe->result) && !blk_mq_add_to_batch(req, iob, nvme_req(req)->status != NVME_SC_SUCCESS, @@ -2013,6 +2023,7 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req) } static void nvme_free_queue(struct nvme_queue *nvmeq) + __context_unsafe(/* frees queue which is no longer in use */) { dma_free_coherent(nvmeq->dev->dev, CQ_SIZE(nvmeq), (void *)nvmeq->cqes, nvmeq->cq_dma_addr); @@ -2107,6 +2118,7 @@ static int nvme_cmb_qdepth(struct nvme_dev *dev, int nr_io_queues, static int nvme_alloc_sq_cmds(struct nvme_dev *dev, struct nvme_queue *nvmeq, int qid) + __context_unsafe(/* safe to allocate sq_cmds without any protection */) { struct pci_dev *pdev = to_pci_dev(dev->dev); @@ -2181,6 +2193,7 @@ static int queue_request_irq(struct nvme_queue *nvmeq) } static void nvme_init_queue(struct nvme_queue *nvmeq, u16 qid) + __context_unsafe(/* initialize unpublished/lock-guarded variables */) { struct nvme_dev *dev = nvmeq->dev;