2022-01-05 07:18:54

by Wenchao Hao

Subject: [PATCH v2] ata: libata-scsi: Make __ata_scsi_queuecmd() parameters check more clearly

This is just a clean code. Since each branch of "if" state would check
scmd->cmd_len, so move the check of scmd->cmd_len out of "if" state to
simplify input parameters check.

And remove redundant init of xlat_func at hand

The patch do not change origin function logic.

Signed-off-by: Wenchao Hao <[email protected]>
---
drivers/ata/libata-scsi.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 313e9475507b..ab8a2833dfec 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -4023,16 +4023,15 @@ int __ata_scsi_queuecmd(struct scsi_cmnd *scmd, struct ata_device *dev)
ata_xlat_func_t xlat_func;
int rc = 0;

+ if (unlikely(!scmd->cmd_len))
+ goto bad_cdb_len;
+
if (dev->class == ATA_DEV_ATA || dev->class == ATA_DEV_ZAC) {
- if (unlikely(!scmd->cmd_len || scmd->cmd_len > dev->cdb_len))
+ if (unlikely(scmd->cmd_len > dev->cdb_len))
goto bad_cdb_len;

xlat_func = ata_get_xlat_func(dev, scsi_op);
} else {
- if (unlikely(!scmd->cmd_len))
- goto bad_cdb_len;
-
- xlat_func = NULL;
if (likely((scsi_op != ATA_16) || !atapi_passthru16)) {
/* relay SCSI command to ATAPI device */
int len = COMMAND_SIZE(scsi_op);
--
2.32.0

2022-01-05 07:39:45

by Damien Le Moal

Subject: Re: [PATCH v2] ata: libata-scsi: Make __ata_scsi_queuecmd() parameters check more clearly

On Wed, 2022-01-05 at 15:27 -0500, Wenchao Hao wrote:
> This is just a clean code. Since each branch of "if" state would check
> scmd->cmd_len, so move the check of scmd->cmd_len out of "if" state to
> simplify input parameters check.
>
> And remove redundant init of xlat_func at hand
>
> The patch do not change origin function logic.
>
> Signed-off-by: Wenchao Hao <[email protected]>
> ---
> drivers/ata/libata-scsi.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index 313e9475507b..ab8a2833dfec 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -4023,16 +4023,15 @@ int __ata_scsi_queuecmd(struct scsi_cmnd *scmd, struct ata_device *dev)
> ata_xlat_func_t xlat_func;
> int rc = 0;
>
> + if (unlikely(!scmd->cmd_len))
> + goto bad_cdb_len;
> +
> if (dev->class == ATA_DEV_ATA || dev->class == ATA_DEV_ZAC) {
> - if (unlikely(!scmd->cmd_len || scmd->cmd_len > dev->cdb_len))
> + if (unlikely(scmd->cmd_len > dev->cdb_len))
> goto bad_cdb_len;
>
> xlat_func = ata_get_xlat_func(dev, scsi_op);
> } else {
> - if (unlikely(!scmd->cmd_len))
> - goto bad_cdb_len;
> -
> - xlat_func = NULL;
> if (likely((scsi_op != ATA_16) || !atapi_passthru16)) {
> /* relay SCSI command to ATAPI device */
> int len = COMMAND_SIZE(scsi_op);

Did you miss my reply ?
This change is OK, but while at it, let's cleanup this function further.
I suggested something like this, which includes your changes.

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index a16ef0030667..ed8be585a98f 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3958,42 +3958,39 @@ int __ata_scsi_queuecmd(struct scsi_cmnd *scmd,
struct ata_device *dev)
{
u8 scsi_op = scmd->cmnd[0];
ata_xlat_func_t xlat_func;
- int rc = 0;
+
+ if (unlikely(!scmd->cmd_len))
+ goto bad_cdb_len;

if (dev->class == ATA_DEV_ATA || dev->class == ATA_DEV_ZAC) {
- if (unlikely(!scmd->cmd_len || scmd->cmd_len > dev->cdb_len))
+ if (unlikely(scmd->cmd_len > dev->cdb_len))
goto bad_cdb_len;

xlat_func = ata_get_xlat_func(dev, scsi_op);
- } else {
- if (unlikely(!scmd->cmd_len))
- goto bad_cdb_len;
+ } else if (scsi_op != ATA_16 || !atapi_passthru16) {
+ /* relay SCSI command to ATAPI device */
+ int len = COMMAND_SIZE(scsi_op);

- xlat_func = NULL;
- if (likely((scsi_op != ATA_16) || !atapi_passthru16)) {
- /* relay SCSI command to ATAPI device */
- int len = COMMAND_SIZE(scsi_op);
- if (unlikely(len > scmd->cmd_len ||
- len > dev->cdb_len ||
- scmd->cmd_len > ATAPI_CDB_LEN))
- goto bad_cdb_len;
+ if (unlikely(len > scmd->cmd_len ||
+ len > dev->cdb_len ||
+ scmd->cmd_len > ATAPI_CDB_LEN))
+ goto bad_cdb_len;

- xlat_func = atapi_xlat;
- } else {
- /* ATA_16 passthru, treat as an ATA command */
- if (unlikely(scmd->cmd_len > 16))
- goto bad_cdb_len;
+ xlat_func = atapi_xlat;
+ } else {
+ /* ATA_16 passthru, treat as an ATA command */
+ if (unlikely(scmd->cmd_len > 16))
+ goto bad_cdb_len;

- xlat_func = ata_get_xlat_func(dev, scsi_op);
- }
+ xlat_func = ata_get_xlat_func(dev, scsi_op);
}

if (xlat_func)
- rc = ata_scsi_translate(dev, scmd, xlat_func);
- else
- ata_scsi_simulate(dev, scmd);
+ return ata_scsi_translate(dev, scmd, xlat_func);

- return rc;
+ ata_scsi_simulate(dev, scmd);
+
+ return 0;

bad_cdb_len:
scmd->result = DID_ERROR << 16;

Do you see any problem with this change ?

--
Damien Le Moal
Western Digital Research

2022-01-05 08:48:40

by Wenchao Hao

Subject: Re: [PATCH v2] ata: libata-scsi: Make __ata_scsi_queuecmd() parameters check more clearly

On 2022/1/5 15:39, Damien Le Moal wrote:
> On Wed, 2022-01-05 at 15:27 -0500, Wenchao Hao wrote:
>> This is just a clean code. Since each branch of "if" state would check
>> scmd->cmd_len, so move the check of scmd->cmd_len out of "if" state to
>> simplify input parameters check.
>>
>> And remove redundant init of xlat_func at hand
>>
>> The patch do not change origin function logic.
>>
>> Signed-off-by: Wenchao Hao <[email protected]>
>> ---
>> drivers/ata/libata-scsi.c | 9 ++++-----
>> 1 file changed, 4 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
>> index 313e9475507b..ab8a2833dfec 100644
>> --- a/drivers/ata/libata-scsi.c
>> +++ b/drivers/ata/libata-scsi.c
>> @@ -4023,16 +4023,15 @@ int __ata_scsi_queuecmd(struct scsi_cmnd *scmd, struct ata_device *dev)
>> ata_xlat_func_t xlat_func;
>> int rc = 0;
>>
>> + if (unlikely(!scmd->cmd_len))
>> + goto bad_cdb_len;
>> +
>> if (dev->class == ATA_DEV_ATA || dev->class == ATA_DEV_ZAC) {
>> - if (unlikely(!scmd->cmd_len || scmd->cmd_len > dev->cdb_len))
>> + if (unlikely(scmd->cmd_len > dev->cdb_len))
>> goto bad_cdb_len;
>>
>> xlat_func = ata_get_xlat_func(dev, scsi_op);
>> } else {
>> - if (unlikely(!scmd->cmd_len))
>> - goto bad_cdb_len;
>> -
>> - xlat_func = NULL;
>> if (likely((scsi_op != ATA_16) || !atapi_passthru16)) {
>> /* relay SCSI command to ATAPI device */
>> int len = COMMAND_SIZE(scsi_op);
>
> Did you miss my reply ?
> This change is OK, but while at it, let's cleanup this function further.
> I suggested something like this, which includes your changes.
>

Maybe I misunderstood your previous reply. I think you ask me to change
prefix.

> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index a16ef0030667..ed8be585a98f 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -3958,42 +3958,39 @@ int __ata_scsi_queuecmd(struct scsi_cmnd *scmd,
> struct ata_device *dev)
> {
> u8 scsi_op = scmd->cmnd[0];
> ata_xlat_func_t xlat_func;
> - int rc = 0;
> +
> + if (unlikely(!scmd->cmd_len))
> + goto bad_cdb_len;
>
> if (dev->class == ATA_DEV_ATA || dev->class == ATA_DEV_ZAC) {
> - if (unlikely(!scmd->cmd_len || scmd->cmd_len > dev->cdb_len))
> + if (unlikely(scmd->cmd_len > dev->cdb_len))
> goto bad_cdb_len;
>
> xlat_func = ata_get_xlat_func(dev, scsi_op);
> - } else {
> - if (unlikely(!scmd->cmd_len))
> - goto bad_cdb_len;
> + } else if (scsi_op != ATA_16 || !atapi_passthru16) {
> + /* relay SCSI command to ATAPI device */
> + int len = COMMAND_SIZE(scsi_op);
>
> - xlat_func = NULL;
> - if (likely((scsi_op != ATA_16) || !atapi_passthru16)) {
> - /* relay SCSI command to ATAPI device */
> - int len = COMMAND_SIZE(scsi_op);
> - if (unlikely(len > scmd->cmd_len ||
> - len > dev->cdb_len ||
> - scmd->cmd_len > ATAPI_CDB_LEN))
> - goto bad_cdb_len;
> + if (unlikely(len > scmd->cmd_len ||
> + len > dev->cdb_len ||
> + scmd->cmd_len > ATAPI_CDB_LEN))
> + goto bad_cdb_len;
>
> - xlat_func = atapi_xlat;
> - } else {
> - /* ATA_16 passthru, treat as an ATA command */
> - if (unlikely(scmd->cmd_len > 16))
> - goto bad_cdb_len;
> + xlat_func = atapi_xlat;
> + } else {
> + /* ATA_16 passthru, treat as an ATA command */
> + if (unlikely(scmd->cmd_len > 16))
> + goto bad_cdb_len;
>
> - xlat_func = ata_get_xlat_func(dev, scsi_op);
> - }
> + xlat_func = ata_get_xlat_func(dev, scsi_op);
> }
>
> if (xlat_func)
> - rc = ata_scsi_translate(dev, scmd, xlat_func);
> - else
> - ata_scsi_simulate(dev, scmd);
> + return ata_scsi_translate(dev, scmd, xlat_func);
>
> - return rc;
> + ata_scsi_simulate(dev, scmd);
> +
> + return 0;
>
> bad_cdb_len:
> scmd->result = DID_ERROR << 16;
>
> Do you see any problem with this change ?
>

This change looks good to me. Should I include this change in next
patch? Or you would do this by youself?

2022-01-05 09:07:18

by Damien Le Moal

Subject: Re: [PATCH v2] ata: libata-scsi: Make __ata_scsi_queuecmd() parameters check more clearly

On Wed, 2022-01-05 at 16:48 +0800, Wenchao Hao wrote:
> On 2022/1/5 15:39, Damien Le Moal wrote:
> > On Wed, 2022-01-05 at 15:27 -0500, Wenchao Hao wrote:
> > > This is just a clean code. Since each branch of "if" state would check
> > > scmd->cmd_len, so move the check of scmd->cmd_len out of "if" state to
> > > simplify input parameters check.
> > >
> > > And remove redundant init of xlat_func at hand
> > >
> > > The patch do not change origin function logic.
> > >
> > > Signed-off-by: Wenchao Hao <[email protected]>
> > > ---
> > > drivers/ata/libata-scsi.c | 9 ++++-----
> > > 1 file changed, 4 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> > > index 313e9475507b..ab8a2833dfec 100644
> > > --- a/drivers/ata/libata-scsi.c
> > > +++ b/drivers/ata/libata-scsi.c
> > > @@ -4023,16 +4023,15 @@ int __ata_scsi_queuecmd(struct scsi_cmnd *scmd, struct ata_device *dev)
> > > ata_xlat_func_t xlat_func;
> > > int rc = 0;
> > >
> > > + if (unlikely(!scmd->cmd_len))
> > > + goto bad_cdb_len;
> > > +
> > > if (dev->class == ATA_DEV_ATA || dev->class == ATA_DEV_ZAC) {
> > > - if (unlikely(!scmd->cmd_len || scmd->cmd_len > dev->cdb_len))
> > > + if (unlikely(scmd->cmd_len > dev->cdb_len))
> > > goto bad_cdb_len;
> > >
> > > xlat_func = ata_get_xlat_func(dev, scsi_op);
> > > } else {
> > > - if (unlikely(!scmd->cmd_len))
> > > - goto bad_cdb_len;
> > > -
> > > - xlat_func = NULL;
> > > if (likely((scsi_op != ATA_16) || !atapi_passthru16)) {
> > > /* relay SCSI command to ATAPI device */
> > > int len = COMMAND_SIZE(scsi_op);
> >
> > Did you miss my reply ?
> > This change is OK, but while at it, let's cleanup this function further.
> > I suggested something like this, which includes your changes.
> >
>
> Maybe I misunderstood your previous reply. I think you ask me to change
> prefix.

Yes, I asked that too. It is OK now.

>
> > diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> > index a16ef0030667..ed8be585a98f 100644
> > --- a/drivers/ata/libata-scsi.c
> > +++ b/drivers/ata/libata-scsi.c
> > @@ -3958,42 +3958,39 @@ int __ata_scsi_queuecmd(struct scsi_cmnd *scmd,
> > struct ata_device *dev)
> > {
> > u8 scsi_op = scmd->cmnd[0];
> > ata_xlat_func_t xlat_func;
> > - int rc = 0;
> > +
> > + if (unlikely(!scmd->cmd_len))
> > + goto bad_cdb_len;
> >
> > if (dev->class == ATA_DEV_ATA || dev->class == ATA_DEV_ZAC) {
> > - if (unlikely(!scmd->cmd_len || scmd->cmd_len > dev->cdb_len))
> > + if (unlikely(scmd->cmd_len > dev->cdb_len))
> > goto bad_cdb_len;
> >
> > xlat_func = ata_get_xlat_func(dev, scsi_op);
> > - } else {
> > - if (unlikely(!scmd->cmd_len))
> > - goto bad_cdb_len;
> > + } else if (scsi_op != ATA_16 || !atapi_passthru16) {
> > + /* relay SCSI command to ATAPI device */
> > + int len = COMMAND_SIZE(scsi_op);
> >
> > - xlat_func = NULL;
> > - if (likely((scsi_op != ATA_16) || !atapi_passthru16)) {
> > - /* relay SCSI command to ATAPI device */
> > - int len = COMMAND_SIZE(scsi_op);
> > - if (unlikely(len > scmd->cmd_len ||
> > - len > dev->cdb_len ||
> > - scmd->cmd_len > ATAPI_CDB_LEN))
> > - goto bad_cdb_len;
> > + if (unlikely(len > scmd->cmd_len ||
> > + len > dev->cdb_len ||
> > + scmd->cmd_len > ATAPI_CDB_LEN))
> > + goto bad_cdb_len;
> >
> > - xlat_func = atapi_xlat;
> > - } else {
> > - /* ATA_16 passthru, treat as an ATA command */
> > - if (unlikely(scmd->cmd_len > 16))
> > - goto bad_cdb_len;
> > + xlat_func = atapi_xlat;
> > + } else {
> > + /* ATA_16 passthru, treat as an ATA command */
> > + if (unlikely(scmd->cmd_len > 16))
> > + goto bad_cdb_len;
> >
> > - xlat_func = ata_get_xlat_func(dev, scsi_op);
> > - }
> > + xlat_func = ata_get_xlat_func(dev, scsi_op);
> > }
> >
> > if (xlat_func)
> > - rc = ata_scsi_translate(dev, scmd, xlat_func);
> > - else
> > - ata_scsi_simulate(dev, scmd);
> > + return ata_scsi_translate(dev, scmd, xlat_func);
> >
> > - return rc;
> > + ata_scsi_simulate(dev, scmd);
> > +
> > + return 0;
> >
> > bad_cdb_len:
> > scmd->result = DID_ERROR << 16;
> >
> > Do you see any problem with this change ?
> >
>
> This change looks good to me. Should I include this change in next
> patch? Or you would do this by youself?

Just include the change in your v3, that's fine. But test please. I did test
what I proposed and it worked fine but I prefer more tests.

And given that the patch does more that just changing the command checks, maybe
change the patch title to something like:

ata: libata-scsi: simplify __ata_scsi_queuecmd()

--
Damien Le Moal
Western Digital Research