[PATCH v4 04/20] nvme: add context annotations for nvme_passthru_{start|stop}

Annotate nvme_passthru_start() and nvme_passthru_end() for Clang
context/thread-safety analysis.

The __cond_acquires() and __cond_releases() annotations model
conditional lock acquisition and release based on a function's return
value. Use a nonzero return value as the abstract condition denoting
that the associated locks have been acquired or released.

This allows the analyzer to track the lock state across the
nvme_passthru_start() / nvme_passthru_end() pair and verify correct
locking semantics.

Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Nilay Shroff <[email protected]>
---
 drivers/nvme/host/nvme.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 0797c3a6a9c1..fba2d7674623 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -1290,10 +1290,16 @@ static inline void nvme_auth_revoke_tls_key(struct nvme_ctrl *ctrl) {};
 
 u32 nvme_command_effects(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 			 u8 opcode);
-u32 nvme_passthru_start(struct nvme_ctrl *ctrl, struct nvme_ns *ns, u8 opcode);
+u32 nvme_passthru_start(struct nvme_ctrl *ctrl, struct nvme_ns *ns, u8 opcode)
+	__cond_acquires(nonzero, &ctrl->subsys->lock)
+	__cond_acquires(nonzero, &ctrl->scan_lock);
+
 int nvme_execute_rq(struct request *rq, bool at_head);
 u32 nvme_passthru_end(struct nvme_ctrl *ctrl, struct nvme_ns *ns, u32 effects,
-		       struct nvme_command *cmd, int status);
+		       struct nvme_command *cmd, int status)
+		       __cond_releases(nonzero, &ctrl->scan_lock)
+		       __cond_releases(nonzero, &ctrl->subsys->lock);
+
 struct nvme_ctrl *nvme_ctrl_from_file(struct file *file);
 struct nvme_ns *nvme_find_get_ns(struct nvme_ctrl *ctrl, unsigned nsid);
 bool nvme_get_ns(struct nvme_ns *ns);
-- 
2.53.0