On Fri, Aug 06, 2021 at 06:43:28AM -0700, Jakub Kicinski wrote:Thanks all ;)
On Fri, 6 Aug 2021 16:21:24 +0800 Kefeng Wang wrote:Me? I was not paying attention to this at all, sorry...
DO_ONCESeems reasonable. Greg does it look good to you?
DEFINE_STATIC_KEY_TRUE(___once_key);
__do_once_done
once_disable_jump(once_key);
INIT_WORK(&w->work, once_deferred);
struct once_work *w;
w->key = key;
schedule_work(&w->work); module unload
//*the key is
destroy*
process_one_work
once_deferred
BUG_ON(!static_key_enabled(work->key));
static_key_count((struct static_key *)x) //*access key, crash*
When module uses DO_ONCE mechanism, it could crash due to the above
concurrency problem, we could reproduce it with link[1].
Fix it by add/put module refcount in the once work process.
[1] https://lore.kernel.org/netdev/eaa6c371-465e-57eb-6be9-f4b16b9d7cbf@xxxxxxxxxx/
I think we can take it thru networking since nobody cared to pick up v1.
Sure, I trust you :)
.