Re: [PATCH v2] libata-scsi: fix read-only bits checking in ata_mselect_*()
So, just reverted this patch.
On Wed, Jul 20, 2016 at 06:59:23AM +0800, tom.t...@gmail.com wrote:
> From: Tom Yan
>
> 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
>
> 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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Re: [PATCH v2] libata-scsi: fix read-only bits checking in ata_mselect_*()
On Wed, Jul 20, 2016 at 06:59:23AM +0800, tom.t...@gmail.com wrote:
> From: Tom Yan
>
> 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
Applied to libata/for-4.8.
This thread was confusing to look at. Please use the "n/N" sequence
tagging for the patches (the -n option of git-format-patch).
Thanks.
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[PATCH v2] libata-scsi: fix read-only bits checking in ata_mselect_*()
From: Tom Yan
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
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) {
+ *fp = i;
+ return -EINVAL;
+ } else {
+ continue;
+ }
+ }
+
+ /* Check the remaining bytes */
if (mpage[i + 2] != buf[i]) {
*fp = i;
return -EINVAL;
@@ -3672,8 +3682,18 @@ static int ata_mselect_control(struct ata_queued_cmd *qc,
*/
ata_msense_control(dev, mpage, false);
for (i = 0; i < CONTROL_MPAGE_LEN - 2; i++) {
- if (i == 0)
- continue;
+ /* Check the first byte */
+ if (i == 0) {
+ /* except the D_SENSE bit */
+ if (mpage[i + 2] & 0xfb != buf[i] & 0xfb) {
+ *fp = i;
+ return -EINVAL;
+ } else {
+ continue;
+ }
+ }
+
+ /* Check the remaining bytes */
if (mpage[2 + i] != buf[i]) {
*fp = i;
return -EINVAL;
--
2.9.0
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