[PATCH v4 13/20] nvme: add context annotations for nvme_subsystems_lock

[Nilay Shroff <nilay@linux.ibm.com>]

The global nvme_subsystems list, nvme_subsystem::entry,
nvme_subsystem::ctrls, and nvme_ctrl::subsys_entry are protected by
nvme_subsystems_lock. Annotate these objects with
__guarded_by(&nvme_subsystems_lock) so that Clang's context analysis
can validate accesses to them.

__nvme_find_get_subsystem() and nvme_validate_cntlid() traverse the
global subsystem list and subsystem controller list and therefore
require callers to hold nvme_subsystems_lock. Annotate both helpers
with __must_hold(&nvme_subsystems_lock).

Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
---
 drivers/nvme/host/core.c | 4 +++-
 drivers/nvme/host/nvme.h | 9 ++++++---
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index f7a4cdb988f1..26bca14e7d81 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -126,8 +126,8 @@ EXPORT_SYMBOL_GPL(nvme_reset_wq);
 struct workqueue_struct *nvme_delete_wq;
 EXPORT_SYMBOL_GPL(nvme_delete_wq);
 
-static LIST_HEAD(nvme_subsystems);
 DEFINE_MUTEX(nvme_subsystems_lock);
+static LIST_HEAD_GUARDED(nvme_subsystems, nvme_subsystems_lock);
 
 static DEFINE_IDA(nvme_instance_ida);
 static dev_t nvme_ctrl_base_chr_devt;
@@ -3200,6 +3200,7 @@ static void nvme_put_subsystem(struct nvme_subsystem *subsys)
 }
 
 static struct nvme_subsystem *__nvme_find_get_subsystem(const char *subsysnqn)
+	__must_hold(&nvme_subsystems_lock)
 {
 	struct nvme_subsystem *subsys;
 
@@ -3244,6 +3245,7 @@ static inline bool nvme_is_io_ctrl(struct nvme_ctrl *ctrl)
 
 static bool nvme_validate_cntlid(struct nvme_subsystem *subsys,
 		struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
+	__must_hold(&nvme_subsystems_lock)
 {
 	struct nvme_ctrl *tmp;
 
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 602d567f3def..607fa9664272 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -361,7 +361,8 @@ struct nvme_ctrl {
 	wait_queue_head_t state_wq;
 
 	struct nvme_subsystem *subsys;
-	struct list_head subsys_entry;
+	struct list_head subsys_entry
+		__guarded_by(&nvme_subsystems_lock);
 
 	struct opal_dev *opal_dev;
 
@@ -493,9 +494,11 @@ struct nvme_subsystem {
 	 * a separate refcount.
 	 */
 	struct kref		ref;
-	struct list_head	entry;
+	struct list_head	entry
+		__guarded_by(&nvme_subsystems_lock);
 	struct mutex		lock;
-	struct list_head	ctrls;
+	struct list_head	ctrls
+		__guarded_by(&nvme_subsystems_lock);
 	struct list_head	nsheads
 		__guarded_by(&lock);
 	char			subnqn[NVMF_NQN_SIZE];
-- 
2.53.0