[process] Hold reference to process during call to step()
authorMichael Brown <mcb30@ipxe.org>
Fri, 13 Jun 2008 02:39:22 +0000 (03:39 +0100)
committerStefan Hajnoczi <stefanha@gmail.com>
Wed, 7 Jul 2010 19:22:19 +0000 (20:22 +0100)
It is conceivable that the process may terminate during the execution
of step().  If nothing else holds a reference to the containing
object, this would cause the object to be freed prior to returning
from step().

Add a ref_get()/ref_put() around the call to ->step() to prevent this
from happening.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Stefan Hajnoczi <stefanha@gmail.com>
src/core/process.c

index 9c13e02..e990f93 100644 (file)
@@ -82,9 +82,11 @@ void step ( void ) {
        list_for_each_entry ( process, &run_queue, list ) {
                list_del ( &process->list );
                list_add_tail ( &process->list, &run_queue );
+               ref_get ( process->refcnt ); /* Inhibit destruction mid-step */
                DBGC2 ( process, "PROCESS %p executing\n", process );
                process->step ( process );
                DBGC2 ( process, "PROCESS %p finished executing\n", process );
+               ref_put ( process->refcnt ); /* Allow destruction */
                break;
        }
 }