Andy Lutomirski <[email protected]> writes: > On Wed, Apr 3, 2013 at 5:47 PM, Eric W. Biederman <[email protected]> > wrote: >> >> No. The patch is still bogus. >> >> If the problem is that we are not coallescing messages in stream_recvmsg >> we need a different fix. >> >> Probably something like: >> >> if (check_creds) { >> /* Never glue messages from different writers */ >> if ((UNIXCB(skb).pid != siocb->scm->pid) || >> (UNIXCB(skb).cred != siocb->scm->cred)) >> break; >> - } else { >> + } else if (test_bit(SOCK_PASSCRED, &sock->flags)) { >> /* Copy credentials */ >> scm_set_cred(siocb->scm, UNIXCB(skb).pid, >> UNIXCB(skb).cred); >> check_creds = 1; >> } > > I'm confused. Isn't this making the problem worse, not better?
For udev that is a don't care. For the case where we are coallescing messages this ensures we always collaesce messages if we don't care about the credentials. Which turns out to be a fix for a long standing pessimization, that no on has bother to complain about. > With my patches, the cost should go way down and it could be made > unconditional, but that's still probably not a good -stable change. Reducing the cost and the complexity as far as we can is good, but we really want small steps as we optimize the case of sending credentials. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
