On Mar 12, 12:20pm, [email protected] ("J. Hannken-Illjes") wrote: -- Subject: Re: DoS attack against TCP services
| Now we have a deadlock, softlck/0 waits for the mutex and therefore | callouts will no longer be processed and ciss holds the mutex and waits | for a callout through cv_timedwait. Thanks for looking into it! Part of the ciss_ioctl_vol() (the pdid part) does things with XS_CTL_POLL so that it does not involve any mutexes. It would be simple to change the ldid part to do the same. Should we do that? | Taking a closer look at the poll loop from sys/dev/ic/ciss.c:537 ... this | code looks wrong in many aspects: | | - Sleeping up to 60 seconds in a function used by a callout is wrong. Yes, but many disk drivers seem to violate that. How do we fix this? Making a separate thread that updates statistics for each driver seems suboptimal? | - Examining variables here we get: tick =3D 10000, etick =3D 16000, | tohz =3D 6000 and i =3D 5999999. As tick is constant (us per hz) | this loop might run for 5999999*60 seconds! I committed a fix for this. Now it should only sleep up to 60 seconds. christos
