Andy Lutomirski <luto@xxxxxxxxxxxxxx> writes:
> On Wed, Apr 3, 2013 at 5:47 PM, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> 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 stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html