• Konstantin Khorenko's avatar
    kernel/module.c: wakeup processes in module_wq on module unload · 5d603311
    Konstantin Khorenko authored
    Fix the race between load and unload a kernel module.
    
    sys_delete_module()
     try_stop_module()
      mod->state = _GOING
    					add_unformed_module()
    					 old = find_module_all()
    					 (old->state == _GOING =>
    					  wait_event_interruptible())
    
    					 During pre-condition
    					 finished_loading() rets 0
    					 schedule()
    					 (never gets waken up later)
     free_module()
      mod->state = _UNFORMED
       list_del_rcu(&mod->list)
       (dels mod from "modules" list)
    
    return
    
    The race above leads to modprobe hanging forever on loading
    a module.
    
    Error paths on loading module call wake_up_all(&module_wq) after
    freeing module, so let's do the same on straight module unload.
    
    Fixes: 6e6de3de ("kernel/module.c: Only return -EEXIST for modules that have finished loading")
    Reviewed-by: default avatarPrarit Bhargava <prarit@redhat.com>
    Signed-off-by: default avatarKonstantin Khorenko <khorenko@virtuozzo.com>
    Signed-off-by: default avatarJessica Yu <jeyu@kernel.org>
    5d603311
module.c 116 KB