1 files changed, 41 insertions, 1 deletions

diff --git a/drivers/misc/cxl/main.c b/drivers/misc/cxl/main.c
index d9be23b24aa3..62e0dfb5f15b 100644
--- a/drivers/misc/cxl/main.c
+++ b/drivers/misc/cxl/main.c
@@ -243,8 +243,10 @@ struct cxl *cxl_alloc_adapter(void)
         if (dev_set_name(&adapter->dev, "card%i", adapter->adapter_num))
                 goto err2;
 
-        return adapter;
+        /* start with context lock taken */
+        atomic_set(&adapter->contexts_num, -1);
 
+        return adapter;
 err2:
         cxl_remove_adapter_nr(adapter);
 err1:
@@ -286,6 +288,44 @@ int cxl_afu_select_best_mode(struct cxl_afu *afu)
         return 0;
 }
 
+int cxl_adapter_context_get(struct cxl *adapter)
+{
+        int rc;
+
+        rc = atomic_inc_unless_negative(&adapter->contexts_num);
+        return rc >= 0 ? 0 : -EBUSY;
+}
+
+void cxl_adapter_context_put(struct cxl *adapter)
+{
+        atomic_dec_if_positive(&adapter->contexts_num);
+}
+
+int cxl_adapter_context_lock(struct cxl *adapter)
+{
+        int rc;
+        /* no active contexts -> contexts_num == 0 */
+        rc = atomic_cmpxchg(&adapter->contexts_num, 0, -1);
+        return rc ? -EBUSY : 0;
+}
+
+void cxl_adapter_context_unlock(struct cxl *adapter)
+{
+        int val = atomic_cmpxchg(&adapter->contexts_num, -1, 0);
+
+        /*
+         * contexts lock taken -> contexts_num == -1
+         * If not true then show a warning and force reset the lock.
+         * This will happen when context_unlock was requested without
+         * doing a context_lock.
+         */
+        if (val != -1) {
+                atomic_set(&adapter->contexts_num, 0);
+                WARN(1, "Adapter context unlocked with %d active contexts",
+                     val);
+        }
+}
+
 static int __init init_cxl(void)
 {
         int rc = 0;