[PATCH v2 03/12] cxl/core: Refactor a cxl_lock_class() out of cxl_nested_lock()

[Dan Williams]

In preparation for upleveling device_lock() lockdep annotation support into
the core, provide a helper to retrieve the lock class. This lock_class
will be used with device_set_lock_class() to identify the CXL nested
locking rules.

Cc: Alison Schofield <alison.schofi...@intel.com>
Cc: Vishal Verma <vishal.l.ve...@intel.com>
Cc: Ira Weiny <ira.we...@intel.com>
Cc: Ben Widawsky <ben.widaw...@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.came...@huawei.com>
Reviewed-by: Dave Jiang <dave.ji...@intel.com>
Reviewed-by: Kevin Tian <kevin.t...@intel.com>
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
 drivers/cxl/cxl.h |   19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 990b6670222e..c9fda9304c54 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -418,13 +418,12 @@ enum cxl_lock_class {
         */
 };
 
-static inline void cxl_nested_lock(struct device *dev)
+static inline int cxl_lock_class(struct device *dev)
 {
        if (is_cxl_port(dev)) {
                struct cxl_port *port = to_cxl_port(dev);
 
-               mutex_lock_nested(&dev->lockdep_mutex,
-                                 CXL_PORT_LOCK + port->depth);
+               return CXL_PORT_LOCK + port->depth;
        } else if (is_cxl_decoder(dev)) {
                struct cxl_port *port = to_cxl_port(dev->parent);
 
@@ -432,14 +431,18 @@ static inline void cxl_nested_lock(struct device *dev)
                 * A decoder is the immediate child of a port, so set
                 * its lock class equal to other child device siblings.
                 */
-               mutex_lock_nested(&dev->lockdep_mutex,
-                                 CXL_PORT_LOCK + port->depth + 1);
+               return CXL_PORT_LOCK + port->depth + 1;
        } else if (is_cxl_nvdimm_bridge(dev))
-               mutex_lock_nested(&dev->lockdep_mutex, CXL_NVDIMM_BRIDGE_LOCK);
+               return CXL_NVDIMM_BRIDGE_LOCK;
        else if (is_cxl_nvdimm(dev))
-               mutex_lock_nested(&dev->lockdep_mutex, CXL_NVDIMM_LOCK);
+               return CXL_NVDIMM_LOCK;
        else
-               mutex_lock_nested(&dev->lockdep_mutex, CXL_ANON_LOCK);
+               return CXL_ANON_LOCK;
+}
+
+static inline void cxl_nested_lock(struct device *dev)
+{
+       mutex_lock_nested(&dev->lockdep_mutex, cxl_lock_class(dev));
 }
 
 static inline void cxl_nested_unlock(struct device *dev)