Re: [PATCH] libata-dev-2.6-ncq: do ata_qc_new inside host_set lock

[Jeff Garzik <jgarzik@pobox.com>]

Tejun Heo wrote:
>  Hello, Jeff.
>  Hello, Jens.
> 
>  This is the third of six misc updates to ncq.
> 
>  ata_qc_new() used to use atomic test_and_set_bit() to allocate qc.
> This makes grabbing host_set lock before calling ata_qc_new_init()
> unncessary, but in most cases (normal SCSI requests) we're holding the
> lock on entry anyway, so the optimization just adds expensive atomic
> bitops.  This patch makes qc allocation performed inside host_set lock
> and uses ffz() instead of atomic bitops.
> 
>  Signed-off-by: Tejun Heo <htejun@gmail.com>

hmmmm, I rather liked the old way.  I'll give this one some thought.