Hi Mike,
Mike Christie wrote:On 02/09/2010 12:59 AM, Tao Ma wrote:If these 2 mutexes are grabed in the same order(in your description,Hi Mike,
I meet with a lockdep warning for iscsi in 2.6.33-rc6.
the lockdep is attached.
If the lockdep output is saying that there is a problem with the iscsi
host taking its mutex then the scsi host mutex, I think that might be
a mistake in the lockdep detection. We always take the iscsi host
mutex then take the scsi host mutex.
Could it get confused if we are scanning two hosts at the same time?
If it is just looking at if a lock is being taken then it would look
like host1 has its ihost->mutex and then took its shost->mutex, but
then host2 could start to get scanned at the same time, and it is
going to take its ihost->mutex. It would then look like we are trying
to grab a ihost->mutex while holding a shost->mutex. However, the
mutexs are not global and they are different instances of the mutex
because each host has its own.
ihost->mutex first and then shost->mutex), there would be no problem.