possible scsi driver bugs with atomic_set/atomic_read and missing barrier

[Mike Christie <michaelc@cs.wisc.edu>]

Hi,

A couple scsi drivers will use a atomic_t for some host/device state.

They will do:

atomic_set(&hba->state, SOME_STATE_VALUE);

in a interrupt or thread or tasklet then in another thread they will do


if (atomic_read(&hba->state) == SOME_STATE_VALUE))



In the Documentation/atomic_ops.txt it says:

	atomic_read does not guarantee that the runtime
	initialization by any other thread is visible yet, so the user of the
	interface must take care of that with a proper implicit or 	explicit memory
	barrier.


Does this mean that the drivers should be doing a


atomic_set(&hba->state, SOME_STATE_VALUE);
smp_mb();