[params] Use reference counters for form parameter lists

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/params.c

@@ -32,6 +32,29 @@ FILE_LICENCE ( GPL2_OR_LATER );
 /** List of all parameter lists */
 static LIST_HEAD ( parameters );
 
+/**
+ * Free form parameter list
+ *
+ * @v refcnt		Reference count
+ */
+static void free_parameters ( struct refcnt *refcnt ) {
+	struct parameters *params =
+		container_of ( refcnt, struct parameters, refcnt );
+	struct parameter *param;
+	struct parameter *tmp;
+
+	DBGC ( params, "PARAMS \"%s\" destroyed\n", params->name );
+
+	/* Free all parameters */
+	list_for_each_entry_safe ( param, tmp, &params->entries, list ) {
+		list_del ( &param->list );
+		free ( param );
+	}
+
+	/* Free parameter list */
+	free ( params );
+}
+
 /**
  * Find form parameter list by name
  *
@@ -63,14 +86,17 @@ struct parameters * create_parameters ( const char *name ) {
 
 	/* Destroy any existing parameter list of this name */
 	params = find_parameters ( name );
-	if ( params )
-		destroy_parameters ( params );
+	if ( params ) {
+		claim_parameters ( params );
+		params_put ( params );
+	}
 
 	/* Allocate parameter list */
 	name_len = ( name ? ( strlen ( name ) + 1 /* NUL */ ) : 0 );
 	params = zalloc ( sizeof ( *params ) + name_len );
 	if ( ! params )
 		return NULL;
+	ref_init ( &params->refcnt, free_parameters );
 	name_copy = ( ( void * ) ( params + 1 ) );
 
 	/* Populate parameter list */
@@ -125,41 +151,3 @@ struct parameter * add_parameter ( struct parameters *params,
 	       params->name, param->key, param->value );
 	return param;
 }
-
-/**
- * Destroy form parameter list
- *
- * @v params		Parameter list
- */
-void destroy_parameters ( struct parameters *params ) {
-	struct parameter *param;
-	struct parameter *tmp;
-
-	DBGC ( params, "PARAMS \"%s\" destroyed\n", params->name );
-
-	/* Free all parameters */
-	list_for_each_entry_safe ( param, tmp, &params->entries, list ) {
-		list_del ( &param->list );
-		free ( param );
-	}
-
-	/* Free parameter list */
-	list_del ( &params->list );
-	free ( params );
-}
-
-/**
- * Claim ownership of form parameter list
- *
- * @v params		Parameter list
- */
-void claim_parameters ( struct parameters *params ) {
-
-	DBGC ( params, "PARAMS \"%s\" claimed\n", params->name );
-
-	/* Remove from list of parameter lists */
-	list_del ( &params->list );
-
-	/* Reinitialise list to allow for subsequent destroy_parameters() */
-	INIT_LIST_HEAD ( &params->list );
-}

src/core/uri.c

@@ -72,8 +72,7 @@ static void dump_uri ( struct uri *uri ) {
 static void free_uri ( struct refcnt *refcnt ) {
 	struct uri *uri = container_of ( refcnt, struct uri, refcnt );
 
-	if ( uri->params )
-		destroy_parameters ( uri->params );
+	params_put ( uri->params );
 	free ( uri );
 }
 
@@ -89,6 +88,7 @@ static void free_uri ( struct refcnt *refcnt ) {
  */
 struct uri * parse_uri ( const char *uri_string ) {
 	struct uri *uri;
+	struct parameters *params;
 	char *raw;
 	char *tmp;
 	char *path;
@@ -111,9 +111,9 @@ struct uri * parse_uri ( const char *uri_string ) {
 	if ( ( tmp = strstr ( raw, "##params" ) ) ) {
 		*tmp = '\0';
 		tmp += 8 /* "##params" */;
-		uri->params = find_parameters ( *tmp ? ( tmp + 1 ) : NULL );
-		if ( uri->params ) {
-			claim_parameters ( uri->params );
+		params = find_parameters ( *tmp ? ( tmp + 1 ) : NULL );
+		if ( params ) {
+			uri->params = claim_parameters ( params );
 		} else {
 			/* Ignore non-existent submission blocks */
 		}

src/hci/commands/param_cmd.c

@@ -74,8 +74,10 @@ static int params_exec ( int argc, char **argv ) {
 		return -ENOMEM;
 
 	/* Destroy parameter list, if applicable */
-	if ( opts.delete )
-		destroy_parameters ( params );
+	if ( opts.delete ) {
+		claim_parameters ( params );
+		params_put ( params );
+	}
 
 	return 0;
 }

src/include/ipxe/params.h

@@ -14,6 +14,8 @@ FILE_LICENCE ( GPL2_OR_LATER );
 
 /** A form parameter list */
 struct parameters {
+	/** Reference count */
+	struct refcnt refcnt;
 	/** List of all parameter lists */
 	struct list_head list;
 	/** Name */
@@ -32,6 +34,43 @@ struct parameter {
 	const char *value;
 };
 
+/**
+ * Increment form parameter list reference count
+ *
+ * @v params		Parameter list, or NULL
+ * @ret params		Parameter list as passed in
+ */
+static inline __attribute__ (( always_inline )) struct parameters *
+params_get ( struct parameters *params ) {
+	ref_get ( &params->refcnt );
+	return params;
+}
+
+/**
+ * Decrement form parameter list reference count
+ *
+ * @v params		Parameter list, or NULL
+ */
+static inline __attribute__ (( always_inline )) void
+params_put ( struct parameters *params ) {
+	ref_put ( &params->refcnt );
+}
+
+/**
+ * Claim ownership of form parameter list
+ *
+ * @v params		Parameter list
+ * @ret params		Parameter list
+ */
+static inline __attribute__ (( always_inline )) struct parameters *
+claim_parameters ( struct parameters *params ) {
+
+	/* Remove from list of parameter lists */
+	list_del ( &params->list );
+
+	return params;
+}
+
 /** Iterate over all form parameters in a list */
 #define for_each_param( param, params )				\
 	list_for_each_entry ( (param), &(params)->entries, list )
@@ -40,7 +79,5 @@ extern struct parameters * find_parameters ( const char *name );
 extern struct parameters * create_parameters ( const char *name );
 extern struct parameter * add_parameter ( struct parameters *params,
 					  const char *key, const char *value );
-extern void destroy_parameters ( struct parameters *params );
-extern void claim_parameters ( struct parameters *params );
 
 #endif /* _IPXE_PARAMS_H */