On Mon, 2013-08-19 at 19:00 +0800, Ding Tianhong wrote: > On 2013/8/19 16:00, Johannes Berg wrote: > > > >> 3.11-rc6's commit 58ad436fcf49 ("genetlink: fix family dump race") > >> gives me the lockdep trace below at startup. > > > > Hmm. Yes, I see now how this happens, not sure why I didn't run into it. > > > > The problem is that genl_family_rcv_msg() is called with the genl_lock > > held, and then calls netlink_dump_start() with it held, creating a > > genl_lock->cb_mutex dependency, but obviously the dump continuation is > > the other way around. > > > > We could use the semaphore instead, I believe, but I don't really > > understand the mutex vs. semaphore well enough to be sure that's > > correct. > > > > johannes > > > it is useless, the logic need to modify or otherwise it will still call lockdep trace. I don't believe so, the semaphore and cb_mutex don't have a dependency yet, afaict. > maybe i could send a patch for it, if you wish. What do you mean? johannes -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html