When the cache_type for the scsi device is changed, the scsi layer
issues a MODE_SELECT command. The caching mode details are communicated
via a request buffer associated with the scsi command with data
direction set as DMA_TO_DEVICE (scsi_mode_select). When this command
reaches the libata layer, as a part of generic initial setup, libata
layer sets up the scatterlist for the command using the scsi command
(ata_scsi_qc_new). This command is then translated by the libata layer
into ATA_CMD_SET_FEATURES (ata_scsi_mode_select_xlat). The libata layer
treats this as a non data command (ata_mselect_caching), since it only
needs an ata taskfile to pass the caching on/off information to the
device. It does not need the scatterlist that has been setup, so it does
not perform dma_map_sg on the scatterlist (ata_qc_issue). Unfortunately,
when this command reaches the libsas layer(sas_ata_qc_issue), libsas
layer sees it as a non data command with a scatterlist. It cannot
extract the correct dma length, since the scatterlist has not been
mapped with dma_map_sg for a DMA operation. When this partially
constructed SAS task reaches pm80xx LLDD, it results in below warning.
"pm80xx_chip_sata_req 6058: The sg list address
start_addr=0x0000000000000000 data_len=0x0end_addr_high=0xffffffff
end_addr_low=0xffffffff has crossed 4G boundary"
This patch assigns appropriate value to num_sectors for ata non data
commands.
Signed-off-by: Jolly Shah <[email protected]>
---
drivers/scsi/libsas/sas_ata.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index 024e5a550759..94ec08cebbaa 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -209,10 +209,12 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
task->num_scatter = si;
}
- if (qc->tf.protocol == ATA_PROT_NODATA)
+ if (qc->tf.protocol == ATA_PROT_NODATA) {
task->data_dir = DMA_NONE;
- else
+ task->num_scatter = 0;
+ } else {
task->data_dir = qc->dma_dir;
+ }
task->scatter = qc->sg;
task->ata_task.retry_count = 1;
task->task_state_flags = SAS_TASK_STATE_PENDING;
--
2.31.0.rc2.261.g7f71774620-goog
在 2021/3/17 3:39, Jolly Shah 写道:
> When the cache_type for the scsi device is changed, the scsi layer
> issues a MODE_SELECT command. The caching mode details are communicated
> via a request buffer associated with the scsi command with data
> direction set as DMA_TO_DEVICE (scsi_mode_select). When this command
> reaches the libata layer, as a part of generic initial setup, libata
> layer sets up the scatterlist for the command using the scsi command
> (ata_scsi_qc_new). This command is then translated by the libata layer
> into ATA_CMD_SET_FEATURES (ata_scsi_mode_select_xlat). The libata layer
> treats this as a non data command (ata_mselect_caching), since it only
> needs an ata taskfile to pass the caching on/off information to the
> device. It does not need the scatterlist that has been setup, so it does
> not perform dma_map_sg on the scatterlist (ata_qc_issue). Unfortunately,
> when this command reaches the libsas layer(sas_ata_qc_issue), libsas
> layer sees it as a non data command with a scatterlist. It cannot
> extract the correct dma length, since the scatterlist has not been
> mapped with dma_map_sg for a DMA operation. When this partially
> constructed SAS task reaches pm80xx LLDD, it results in below warning.
>
> "pm80xx_chip_sata_req 6058: The sg list address
> start_addr=0x0000000000000000 data_len=0x0end_addr_high=0xffffffff
> end_addr_low=0xffffffff has crossed 4G boundary"
>
> This patch assigns appropriate value to num_sectors for ata non data
> commands.
>
> Signed-off-by: Jolly Shah <[email protected]>
> ---
> drivers/scsi/libsas/sas_ata.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
> index 024e5a550759..94ec08cebbaa 100644
> --- a/drivers/scsi/libsas/sas_ata.c
> +++ b/drivers/scsi/libsas/sas_ata.c
> @@ -209,10 +209,12 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
> task->num_scatter = si;
> }
>
> - if (qc->tf.protocol == ATA_PROT_NODATA)
> + if (qc->tf.protocol == ATA_PROT_NODATA) {
> task->data_dir = DMA_NONE;
> - else
> + task->num_scatter = 0;
> + } else {
> task->data_dir = qc->dma_dir;
> + }
> task->scatter = qc->sg;
> task->ata_task.retry_count = 1;
> task->task_state_flags = SAS_TASK_STATE_PENDING;
>
Thanks for the patch. Except the warning, any functional errors?
The code looks good to me,
Reviewed-by: Jason Yan <[email protected]>
On 16/03/2021 19:39, Jolly Shah wrote:
> When the cache_type for the scsi device is changed, the scsi layer
> issues a MODE_SELECT command. The caching mode details are communicated
> via a request buffer associated with the scsi command with data
> direction set as DMA_TO_DEVICE (scsi_mode_select). When this command
> reaches the libata layer, as a part of generic initial setup, libata
> layer sets up the scatterlist for the command using the scsi command
> (ata_scsi_qc_new). This command is then translated by the libata layer
> into ATA_CMD_SET_FEATURES (ata_scsi_mode_select_xlat). The libata layer
> treats this as a non data command (ata_mselect_caching), since it only
> needs an ata taskfile to pass the caching on/off information to the
> device. It does not need the scatterlist that has been setup, so it does
> not perform dma_map_sg on the scatterlist (ata_qc_issue).
So if we don't perform the dma_map_sg() on the sgl at this point, then
it seems to me that we should not perform for_each_sg() on it either,
right? That is still what happens in sas_ata_qc_issue() in this case.
> Unfortunately,
> when this command reaches the libsas layer(sas_ata_qc_issue), libsas
> layer sees it as a non data command with a scatterlist. It cannot
> extract the correct dma length, since the scatterlist has not been
> mapped with dma_map_sg for a DMA operation. When this partially
> constructed SAS task reaches pm80xx LLDD, it results in below warning.
>
> "pm80xx_chip_sata_req 6058: The sg list address
> start_addr=0x0000000000000000 data_len=0x0end_addr_high=0xffffffff
> end_addr_low=0xffffffff has crossed 4G boundary"
>
> This patch assigns appropriate value to num_sectors for ata non data
> commands.
>
> Signed-off-by: Jolly Shah <[email protected]>
> ---
> drivers/scsi/libsas/sas_ata.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
> index 024e5a550759..94ec08cebbaa 100644
> --- a/drivers/scsi/libsas/sas_ata.c
> +++ b/drivers/scsi/libsas/sas_ata.c
> @@ -209,10 +209,12 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
> task->num_scatter = si;
> }
>
> - if (qc->tf.protocol == ATA_PROT_NODATA)
> + if (qc->tf.protocol == ATA_PROT_NODATA) {
> task->data_dir = DMA_NONE;
> - else
> + task->num_scatter = 0;
task->num_scatter has already been set in this function. Best not set it
twice.
Thanks,
John
> + } else {
> task->data_dir = qc->dma_dir;
> + }
> task->scatter = qc->sg;
> task->ata_task.retry_count = 1;
> task->task_state_flags = SAS_TASK_STATE_PENDING;
>
Hi Jason,
Thanks for the review.
On Tue, Mar 16, 2021 at 6:50 PM Jason Yan <[email protected]> wrote:
>
>
> 在 2021/3/17 3:39, Jolly Shah 写道:
> > When the cache_type for the scsi device is changed, the scsi layer
> > issues a MODE_SELECT command. The caching mode details are communicated
> > via a request buffer associated with the scsi command with data
> > direction set as DMA_TO_DEVICE (scsi_mode_select). When this command
> > reaches the libata layer, as a part of generic initial setup, libata
> > layer sets up the scatterlist for the command using the scsi command
> > (ata_scsi_qc_new). This command is then translated by the libata layer
> > into ATA_CMD_SET_FEATURES (ata_scsi_mode_select_xlat). The libata layer
> > treats this as a non data command (ata_mselect_caching), since it only
> > needs an ata taskfile to pass the caching on/off information to the
> > device. It does not need the scatterlist that has been setup, so it does
> > not perform dma_map_sg on the scatterlist (ata_qc_issue). Unfortunately,
> > when this command reaches the libsas layer(sas_ata_qc_issue), libsas
> > layer sees it as a non data command with a scatterlist. It cannot
> > extract the correct dma length, since the scatterlist has not been
> > mapped with dma_map_sg for a DMA operation. When this partially
> > constructed SAS task reaches pm80xx LLDD, it results in below warning.
> >
> > "pm80xx_chip_sata_req 6058: The sg list address
> > start_addr=0x0000000000000000 data_len=0x0end_addr_high=0xffffffff
> > end_addr_low=0xffffffff has crossed 4G boundary"
> >
> > This patch assigns appropriate value to num_sectors for ata non data
> > commands.
> >
> > Signed-off-by: Jolly Shah <[email protected]>
> > ---
> > drivers/scsi/libsas/sas_ata.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
> > index 024e5a550759..94ec08cebbaa 100644
> > --- a/drivers/scsi/libsas/sas_ata.c
> > +++ b/drivers/scsi/libsas/sas_ata.c
> > @@ -209,10 +209,12 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
> > task->num_scatter = si;
> > }
> >
> > - if (qc->tf.protocol == ATA_PROT_NODATA)
> > + if (qc->tf.protocol == ATA_PROT_NODATA) {
> > task->data_dir = DMA_NONE;
> > - else
> > + task->num_scatter = 0;
> > + } else {
> > task->data_dir = qc->dma_dir;
> > + }
> > task->scatter = qc->sg;
> > task->ata_task.retry_count = 1;
> > task->task_state_flags = SAS_TASK_STATE_PENDING;
> >
>
> Thanks for the patch. Except the warning, any functional errors?
>
No functional errors observed.
Thanks,
Jolly Shah
> The code looks good to me,
>
> Reviewed-by: Jason Yan <[email protected]>
Hi John,
Thanks for the review.
On Wed, Mar 17, 2021 at 4:44 AM John Garry <[email protected]> wrote:
>
> On 16/03/2021 19:39, Jolly Shah wrote:
> > When the cache_type for the scsi device is changed, the scsi layer
> > issues a MODE_SELECT command. The caching mode details are communicated
> > via a request buffer associated with the scsi command with data
> > direction set as DMA_TO_DEVICE (scsi_mode_select). When this command
> > reaches the libata layer, as a part of generic initial setup, libata
> > layer sets up the scatterlist for the command using the scsi command
> > (ata_scsi_qc_new). This command is then translated by the libata layer
> > into ATA_CMD_SET_FEATURES (ata_scsi_mode_select_xlat). The libata layer
> > treats this as a non data command (ata_mselect_caching), since it only
> > needs an ata taskfile to pass the caching on/off information to the
> > device. It does not need the scatterlist that has been setup, so it does
> > not perform dma_map_sg on the scatterlist (ata_qc_issue).
>
> So if we don't perform the dma_map_sg() on the sgl at this point, then
> it seems to me that we should not perform for_each_sg() on it either,
> right? That is still what happens in sas_ata_qc_issue() in this case.
>
Yes that's right. To avoid that, I can add elseif block for
ATA_PROT_NODATA before for_each_sg() is performed. Currently there's
existing code block for ATA_PROT_NODATA after for_each_sg() is
performed,
reused that to reset num_scatter. Please suggest.
> > Unfortunately,
> > when this command reaches the libsas layer(sas_ata_qc_issue), libsas
> > layer sees it as a non data command with a scatterlist. It cannot
> > extract the correct dma length, since the scatterlist has not been
> > mapped with dma_map_sg for a DMA operation. When this partially
> > constructed SAS task reaches pm80xx LLDD, it results in below warning.
> >
> > "pm80xx_chip_sata_req 6058: The sg list address
> > start_addr=0x0000000000000000 data_len=0x0end_addr_high=0xffffffff
> > end_addr_low=0xffffffff has crossed 4G boundary"
> >
> > This patch assigns appropriate value to num_sectors for ata non data
> > commands.
> >
> > Signed-off-by: Jolly Shah <[email protected]>
> > ---
> > drivers/scsi/libsas/sas_ata.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
> > index 024e5a550759..94ec08cebbaa 100644
> > --- a/drivers/scsi/libsas/sas_ata.c
> > +++ b/drivers/scsi/libsas/sas_ata.c
> > @@ -209,10 +209,12 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
> > task->num_scatter = si;
> > }
> >
> > - if (qc->tf.protocol == ATA_PROT_NODATA)
> > + if (qc->tf.protocol == ATA_PROT_NODATA) {
> > task->data_dir = DMA_NONE;
> > - else
> > + task->num_scatter = 0;
>
> task->num_scatter has already been set in this function. Best not set it
> twice.
>
Sure. Please suggest if I should update patch to above suggested
approach. That will avoid setting num_scatter twice.
Thanks,
Jolly Shah
> Thanks,
> John
>
> > + } else {
> > task->data_dir = qc->dma_dir;
> > + }
> > task->scatter = qc->sg;
> > task->ata_task.retry_count = 1;
> > task->task_state_flags = SAS_TASK_STATE_PENDING;
> >
>
On 18/03/2021 00:24, Jolly Shah wrote:
> Hi John,
>
> Thanks for the review.
>
>
> On Wed, Mar 17, 2021 at 4:44 AM John Garry <[email protected]> wrote:
>>
>> On 16/03/2021 19:39, Jolly Shah wrote:
>>> When the cache_type for the scsi device is changed, the scsi layer
>>> issues a MODE_SELECT command. The caching mode details are communicated
>>> via a request buffer associated with the scsi command with data
>>> direction set as DMA_TO_DEVICE (scsi_mode_select). When this command
>>> reaches the libata layer, as a part of generic initial setup, libata
>>> layer sets up the scatterlist for the command using the scsi command
>>> (ata_scsi_qc_new). This command is then translated by the libata layer
>>> into ATA_CMD_SET_FEATURES (ata_scsi_mode_select_xlat). The libata layer
>>> treats this as a non data command (ata_mselect_caching), since it only
>>> needs an ata taskfile to pass the caching on/off information to the
>>> device. It does not need the scatterlist that has been setup, so it does
>>> not perform dma_map_sg on the scatterlist (ata_qc_issue).
>>
>> So if we don't perform the dma_map_sg() on the sgl at this point, then
>> it seems to me that we should not perform for_each_sg() on it either,
>> right? That is still what happens in sas_ata_qc_issue() in this case.
>>
Hi Jolly Shah,
>
> Yes that's right. To avoid that, I can add elseif block for
> ATA_PROT_NODATA before for_each_sg() is performed. Currently there's
> existing code block for ATA_PROT_NODATA after for_each_sg() is
> performed,
> reused that to reset num_scatter. Please suggest.
>
How about just combine the 2x if-else statements into 1x if-elif-else
statement, like:
if (ata_is_atapi(qc->tf.protocol)) {
memcpy(task->ata_task.atapi_packet, qc->cdb, qc->dev->cdb_len);
task->total_xfer_len = qc->nbytes;
task->num_scatter = qc->n_elem;
task->data_dir = qc->dma_dir;
} else if (qc->tf.protocol == ATA_PROT_NODATA) {
task->data_dir = DMA_NONE;
} else {
for_each_sg(qc->sg, sg, qc->n_elem, si)
xfer += sg_dma_len(sg);
task->total_xfer_len = xfer;
task->num_scatter = si;
task->data_dir = qc->dma_dir;
}
>>> Unfortunately,
>>> when this command reaches the libsas layer(sas_ata_qc_issue), libsas
>>> layer sees it as a non data command with a scatterlist. It cannot
>>> extract the correct dma length, since the scatterlist has not been
>>> mapped with dma_map_sg for a DMA operation. When this partially
>>> constructed SAS task reaches pm80xx LLDD, it results in below warning.
>>>
>>> "pm80xx_chip_sata_req 6058: The sg list address
>>> start_addr=0x0000000000000000 data_len=0x0end_addr_high=0xffffffff
>>> end_addr_low=0xffffffff has crossed 4G boundary"
>>>
>>> This patch assigns appropriate value to num_sectors for ata non data
>>> commands.
>>>
>>> Signed-off-by: Jolly Shah <[email protected]>
>>> ---
>>> drivers/scsi/libsas/sas_ata.c | 6 ++++--
>>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
>>> index 024e5a550759..94ec08cebbaa 100644
>>> --- a/drivers/scsi/libsas/sas_ata.c
>>> +++ b/drivers/scsi/libsas/sas_ata.c
>>> @@ -209,10 +209,12 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
>>> task->num_scatter = si;
>>> }
>>>
>>> - if (qc->tf.protocol == ATA_PROT_NODATA)
>>> + if (qc->tf.protocol == ATA_PROT_NODATA) {
>>> task->data_dir = DMA_NONE;
>>> - else
>>> + task->num_scatter = 0;
>>
>> task->num_scatter has already been set in this function. Best not set it
>> twice.
>>
>
> Sure. Please suggest if I should update patch to above suggested
> approach. That will avoid setting num_scatter twice.
>
Thanks,
John
BTW, could we add a fixes tag?
Hi John,
On Thu, Mar 18, 2021 at 9:19 AM John Garry <[email protected]> wrote:
>
> On 18/03/2021 00:24, Jolly Shah wrote:
> > Hi John,
> >
> > Thanks for the review.
> >
> >
> > On Wed, Mar 17, 2021 at 4:44 AM John Garry <[email protected]> wrote:
> >>
> >> On 16/03/2021 19:39, Jolly Shah wrote:
> >>> When the cache_type for the scsi device is changed, the scsi layer
> >>> issues a MODE_SELECT command. The caching mode details are communicated
> >>> via a request buffer associated with the scsi command with data
> >>> direction set as DMA_TO_DEVICE (scsi_mode_select). When this command
> >>> reaches the libata layer, as a part of generic initial setup, libata
> >>> layer sets up the scatterlist for the command using the scsi command
> >>> (ata_scsi_qc_new). This command is then translated by the libata layer
> >>> into ATA_CMD_SET_FEATURES (ata_scsi_mode_select_xlat). The libata layer
> >>> treats this as a non data command (ata_mselect_caching), since it only
> >>> needs an ata taskfile to pass the caching on/off information to the
> >>> device. It does not need the scatterlist that has been setup, so it does
> >>> not perform dma_map_sg on the scatterlist (ata_qc_issue).
> >>
> >> So if we don't perform the dma_map_sg() on the sgl at this point, then
> >> it seems to me that we should not perform for_each_sg() on it either,
> >> right? That is still what happens in sas_ata_qc_issue() in this case.
> >>
>
> Hi Jolly Shah,
>
> >
> > Yes that's right. To avoid that, I can add elseif block for
> > ATA_PROT_NODATA before for_each_sg() is performed. Currently there's
> > existing code block for ATA_PROT_NODATA after for_each_sg() is
> > performed,
> > reused that to reset num_scatter. Please suggest.
> >
>
> How about just combine the 2x if-else statements into 1x if-elif-else
> statement, like:
>
>
> if (ata_is_atapi(qc->tf.protocol)) {
> memcpy(task->ata_task.atapi_packet, qc->cdb, qc->dev->cdb_len);
> task->total_xfer_len = qc->nbytes;
> task->num_scatter = qc->n_elem;
> task->data_dir = qc->dma_dir;
> } else if (qc->tf.protocol == ATA_PROT_NODATA) {
> task->data_dir = DMA_NONE;
> } else {
> for_each_sg(qc->sg, sg, qc->n_elem, si)
> xfer += sg_dma_len(sg);
>
> task->total_xfer_len = xfer;
> task->num_scatter = si;
> task->data_dir = qc->dma_dir;
> }
>
Updated in v2.
> >>> Unfortunately,
> >>> when this command reaches the libsas layer(sas_ata_qc_issue), libsas
> >>> layer sees it as a non data command with a scatterlist. It cannot
> >>> extract the correct dma length, since the scatterlist has not been
> >>> mapped with dma_map_sg for a DMA operation. When this partially
> >>> constructed SAS task reaches pm80xx LLDD, it results in below warning.
> >>>
> >>> "pm80xx_chip_sata_req 6058: The sg list address
> >>> start_addr=0x0000000000000000 data_len=0x0end_addr_high=0xffffffff
> >>> end_addr_low=0xffffffff has crossed 4G boundary"
> >>>
> >>> This patch assigns appropriate value to num_sectors for ata non data
> >>> commands.
> >>>
> >>> Signed-off-by: Jolly Shah <[email protected]>
> >>> ---
> >>> drivers/scsi/libsas/sas_ata.c | 6 ++++--
> >>> 1 file changed, 4 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
> >>> index 024e5a550759..94ec08cebbaa 100644
> >>> --- a/drivers/scsi/libsas/sas_ata.c
> >>> +++ b/drivers/scsi/libsas/sas_ata.c
> >>> @@ -209,10 +209,12 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
> >>> task->num_scatter = si;
> >>> }
> >>>
> >>> - if (qc->tf.protocol == ATA_PROT_NODATA)
> >>> + if (qc->tf.protocol == ATA_PROT_NODATA) {
> >>> task->data_dir = DMA_NONE;
> >>> - else
> >>> + task->num_scatter = 0;
> >>
> >> task->num_scatter has already been set in this function. Best not set it
> >> twice.
> >>
> >
> > Sure. Please suggest if I should update patch to above suggested
> > approach. That will avoid setting num_scatter twice.
> >
>
> Thanks,
> John
>
> BTW, could we add a fixes tag?
Added in v2.
Thanks,
Jolly