trusty (9) dev_clone.9freebsd.gz

NAME

     dev_clone, drain_dev_clone_events — eventhandler for name-based device cloning in devfs

SYNOPSIS

     #include <sys/param.h>
     #include <sys/conf.h>

     void
     clone_handler(void *arg, struct ucred *cr, char *name, int namelen, struct cdev **dev);

     EVENTHANDLER_REGISTER(dev_clone, clone_handler, arg, priority);

     void
     drain_dev_clone_events();

DESCRIPTION

     A device driver may register a listener that will be notified each time a name lookup on the devfs(5) mount
     point fails to find the vnode.  A listener shall be registered for the dev_clone event.  When called, it is
     supplied with the first argument arg that was specified at handler registration time, appropriate
     credentials cr, and a name name of length namelen that we look for.  If the handler decides that the name
     is appropriate and wants to create the device that will be associated with the name, it should return it to
     devfs in the dev argument.

     The drain_dev_clone_events() function is a barrier.  It is guaranteed that all calls to eventhandlers for
     dev_clone that were started before drain_dev_clone_events() call, are finished before it returns control.

SEE ALSO

     devfs(5), namei(9)