--- On Mon, 2/28/11, Matthew Wilcox <matthew@xxxxxx> wrote:
> Before 2.6.37, there's a per-host lock acquired in the scsi
> layer that
> prevents queuecommand being called twice for the same host
> simultaneously.
> If your driver is drivign two cards, then it can still be
> executing
> twice ... but it's a rare driver that has global
> instead of per-host
> state to protect.
If precautions are taken (to protect shared data), I assume it is safe to spin_unlock(host->host_lock) - at the entry in queuecommand() and spin_lock(host->host_lock) - at the exit, to make it MT?
(I believe I've seen this done)
thanks,
John
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