Re: [PATCH 1/2] libata: get rid of ATA_MAX_QUEUE loop in ata_qc_complete_multiple()

From: Tejun Heo
Date: Thu Oct 23 2008 - 00:14:51 EST


Jens Axboe wrote:
> @@ -4811,16 +4811,19 @@ int ata_qc_complete_multiple(struct ata_port *ap, u32 qc_active)
> return -EINVAL;
> }
>
> - for (i = 0; i < ATA_MAX_QUEUE; i++) {
> + while (done_mask) {
> struct ata_queued_cmd *qc;
> + unsigned int next = __ffs(done_mask);
>
> - if (!(done_mask & (1 << i)))
> - continue;
> -
> - if ((qc = ata_qc_from_tag(ap, i))) {
> + qc = ata_qc_from_tag(ap, i + next);
> + if (qc) {
> ata_qc_complete(qc);
> nr_done++;
> }
> + if (++next >= ATA_MAX_QUEUE)
> + break;
> + i += next;
> + done_mask >>= next;

Shouldn't this be...

i += next + 1;
if (i >= ATA_MAX_QUEUE)
break;

or better...

while (done_mask) {
struct ata_queued_cmd *qc;
unsigned int next = __ffs(done_mask);

tag += next;
if ((qc = ata_qc_from_tag(ap, tag))) {
ata_qc_complete(qc);
nr_done++;
}
next++;
tag += next;
done_mask >>= next;
}

done_mask is guaranteed to be zero at when tag reaches ATA_MAX_QUEUE.

Thanks.

--
tejun
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