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nvme: add context annotations for nvme_queue::sq_lock

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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 <hch@lst.de>
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
This commit is contained in:
Nilay Shroff
2026-07-13 17:24:16 +05:30
committed by Keith Busch
parent 50be6cb15f
commit 1f3d29bdca
1 changed files with 17 additions and 4 deletions
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21
drivers/nvme/host/pci.c
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@@ -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;