On Fri, Jan 20, 2017 at 5:57 AM, Cong Wang <xiyou.wangcong@xxxxxxxxx> wrote: >>>>>> > Why do we do autobind there, anyway, and why is it conditional on >>>>>> > SOCK_PASSCRED? Note that e.g. for SOCK_STREAM we can bloody well get >>>>>> > to sending stuff without autobind ever done - just use socketpair() >>>>>> > to create that sucker and we won't be going through the connect() >>>>>> > at all. >>>>>> >>>>>> In the case Dmitry reported, unix_dgram_sendmsg() calls unix_autobind(), >>>>>> not SOCK_STREAM. >>>>> >>>>> Yes, I've noticed. What I'm asking is what in there needs autobind triggered >>>>> on sendmsg and why doesn't the same need affect the SOCK_STREAM case? >>>>> >>>>>> I guess some lock, perhaps the u->bindlock could be dropped before >>>>>> acquiring the next one (sb_writer), but I need to double check. >>>>> >>>>> Bad idea, IMO - do you *want* autobind being able to come through while >>>>> bind(2) is busy with mknod? >>>> >>>> >>>> Ping. This is still happening on HEAD. >>>> >>> >>> Thanks for your reminder. Mind to give the attached patch (compile only) >>> a try? I take another approach to fix this deadlock, which moves the >>> unix_mknod() out of unix->bindlock. Not sure if there is any unexpected >>> impact with this way. >> >> >> I instantly hit: >> > > Oh, sorry about it, I forgot to initialize struct path... > > Attached is the updated version, I just did a boot test, no crash at least. ;) > > Thanks! This works! I did not see the deadlock warning, nor any other related crashes. Tested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
