So, just reverted this patch.
On Wed, Jul 20, 2016 at 06:59:23AM +0800, tom.ty89@xxxxxxxxx wrote:
> From: Tom Yan <tom.ty89@xxxxxxxxx>
>
> Commit 7780081c1f04 ("libata-scsi: Set information sense field for
> invalid parameter") changed how ata_mselect_*() make sure read-only
> bits are not modified. The new implementation introduced a bug that
> the read-only bits in the byte that has a changeable bit will not
> be checked.
>
> Added the necessary check, with comments explaining the heuristic.
>
> Signed-off-by: Tom Yan <tom.ty89@xxxxxxxxx>
>
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index 06afe63..b47c3ce 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -3617,8 +3617,18 @@ static int ata_mselect_caching(struct ata_queued_cmd *qc,
> */
> ata_msense_caching(dev->id, mpage, false);
> for (i = 0; i < CACHE_MPAGE_LEN - 2; i++) {
> - if (i == 0)
> - continue;
> + /* Check the first byte */
> + if (i == 0) {
> + /* except the WCE bit */
> + if (mpage[i + 2] & 0xfb != buf[i] & 0xfb) {
This not only triggered compiler warning but is actually wrong. The
above is
mpage[i + 1] & (0xfb != buf[i]) & 0xfb
which is non-sensical. So, this patch wasn't tested at all. Not even
compile test. Please don't do this.
Thanks.
--
tejun
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