Correct use of ap->lock versus ap->host->lock ?

[Mark Lord <liml@rtr.ca>]

Jeff / Tejun / Alan,

I'm trying to sort out the spinlocks in sata_mv.

In some places, the existing code uses ap->lock.
But in others, notably the interrupt handling, it uses ap->host->lock.

This looks buggy to me, and I'm wondering how to make it bulletproof.

The interrupt handler for each port should really be using ap->lock, right?
But accesses to the host-level (shared among ports) interrupt registers
probably requires ap->host->lock.  Right again?

>From a libata core point of view, what does ap->host->lock protect?

???

Thanks