ocxl: Fix potential memory leak on context creation

If we couldn't fully init a context, we were leaking memory.

Fixes: b9721d27 ("ocxl: Allow external drivers to use OpenCAPI contexts")
Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
Acked-by: Andrew Donnellan <ajd@linux.ibm.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191209105513.8566-1-fbarrat@linux.ibm.com

drivers/misc/ocxl/context.c

@@ -10,18 +10,17 @@ int ocxl_context_alloc(struct ocxl_context **context, struct ocxl_afu *afu,
 	int pasid;
 	struct ocxl_context *ctx;
 
-	*context = kzalloc(sizeof(struct ocxl_context), GFP_KERNEL);
-	if (!*context)
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
 		return -ENOMEM;
 
-	ctx = *context;
-
 	ctx->afu = afu;
 	mutex_lock(&afu->contexts_lock);
 	pasid = idr_alloc(&afu->contexts_idr, ctx, afu->pasid_base,
 			afu->pasid_base + afu->pasid_max, GFP_KERNEL);
 	if (pasid < 0) {
 		mutex_unlock(&afu->contexts_lock);
+		kfree(ctx);
 		return pasid;
 	}
 	afu->pasid_count++;
@@ -43,6 +42,7 @@ int ocxl_context_alloc(struct ocxl_context **context, struct ocxl_afu *afu,
 	 * duration of the life of the context
 	 */
 	ocxl_afu_get(afu);
+	*context = ctx;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(ocxl_context_alloc);