Re: [PATCH] target: Make transport_lookup_cmd_lun() locking IRQ-safe

[Christoph Hellwig <hch@infradead.org>]

On Mon, Jun 13, 2011 at 08:44:05PM -0700, Roland Dreier wrote:
> From: Roland Dreier <roland@purestorage.com>
> 
> transport_lookup_cmd_lun() may be called from interrupt context (eg
> tcm_loop_allocate_core_cmd() calls it, and it has a comment that says,
> "Can be called from interrupt context"), so it needs to use
> spin_lock_irqsave() instead of spin_lock_irq() to avoid enabling
> interrupts at the wrong time.
> 
> (And indeed the last set of lock operations, on lun_cmd_lock, were
> already using spin_lock_irqsave(), so we just need to fix the other
> two locks we take)

It currently is, but I think we'd better be off stopping to call it from
IRQ context.  Soon after we offload the work to thread context anyway.
By moving the point of offloading a little earlier we can simply the
calling conventions a lot, and keep the amount of code that needs
IRQ-safe locking minimal.