[PATCH] ata: ahci_st: fixup layering violations / drvdata errors

[PATCH] ata: ahci_st: fixup layering violations / drvdata errors

[Brian Norris]

When working on another SATA driver that uses libahci_platform, I
noticed an error in this driver; it tries to the the driver data for its
device, while libata also thinks it can set the driver data. See:

  ahci_platform_init_host()
  -> ata_host_alloc_pinfo()
     -> ata_host_alloc()
        -> dev_set_drvdata()

So instead of sticking the IP-specific platform data into drvdata, let's
use the plat_data variable that is reserved for this use.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Cc: Srinivas Kandagatla <srinivas.kandagatla@gmail.com>
Cc: Maxime Coquelin <maxime.coquelin@st.com>
Cc: Patrice Chotard <patrice.chotard@st.com>
---
This is ONLY compile tested; I don't have hardware to run. This looks like it
could have ramifications on suspend/resume support, and hot device removal
(e.g., sysfs unbind), so it might qualify as -stable, if someone can test it

 drivers/ata/ahci_st.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/ata/ahci_st.c b/drivers/ata/ahci_st.c
index bc971af262e7..2bd2375c2ab1 100644
--- a/drivers/ata/ahci_st.c
+++ b/drivers/ata/ahci_st.c
@@ -37,7 +37,6 @@ struct st_ahci_drv_data {
 	struct reset_control *pwr;
 	struct reset_control *sw_rst;
 	struct reset_control *pwr_rst;
-	struct ahci_host_priv *hpriv;
 };
 
 static void st_ahci_configure_oob(void __iomem *mmio)
@@ -57,7 +56,9 @@ static void st_ahci_configure_oob(void __iomem *mmio)
 
 static int st_ahci_deassert_resets(struct device *dev)
 {
-	struct st_ahci_drv_data *drv_data = dev_get_drvdata(dev);
+	struct ata_host *host = dev_get_drvdata(dev);
+	struct ahci_host_priv *hpriv = host->private_data;
+	struct st_ahci_drv_data *drv_data = hpriv->plat_data;
 	int err;
 
 	if (drv_data->pwr) {
@@ -68,7 +69,7 @@ static int st_ahci_deassert_resets(struct device *dev)
 		}
 	}
 
-	st_ahci_configure_oob(drv_data->hpriv->mmio);
+	st_ahci_configure_oob(hpriv->mmio);
 
 	if (drv_data->sw_rst) {
 		err = reset_control_deassert(drv_data->sw_rst);
@@ -92,8 +93,8 @@ static int st_ahci_deassert_resets(struct device *dev)
 static void st_ahci_host_stop(struct ata_host *host)
 {
 	struct ahci_host_priv *hpriv = host->private_data;
+	struct st_ahci_drv_data *drv_data = hpriv->plat_data;
 	struct device *dev = host->dev;
-	struct st_ahci_drv_data *drv_data = dev_get_drvdata(dev);
 	int err;
 
 	if (drv_data->pwr) {
@@ -107,7 +108,9 @@ static void st_ahci_host_stop(struct ata_host *host)
 
 static int st_ahci_probe_resets(struct platform_device *pdev)
 {
-	struct st_ahci_drv_data *drv_data = platform_get_drvdata(pdev);
+	struct ata_host *host = dev_get_drvdata(&pdev->dev);
+	struct ahci_host_priv *hpriv = host->private_data;
+	struct st_ahci_drv_data *drv_data = hpriv->plat_data;
 
 	drv_data->pwr = devm_reset_control_get(&pdev->dev, "pwr-dwn");
 	if (IS_ERR(drv_data->pwr)) {
@@ -161,8 +164,7 @@ static int st_ahci_probe(struct platform_device *pdev)
 	hpriv = ahci_platform_get_resources(pdev);
 	if (IS_ERR(hpriv))
 		return PTR_ERR(hpriv);
-
-	drv_data->hpriv = hpriv;
+	hpriv->plat_data = drv_data;
 
 	err = st_ahci_probe_resets(pdev);
 	if (err)
@@ -185,8 +187,9 @@ static int st_ahci_probe(struct platform_device *pdev)
 #ifdef CONFIG_PM_SLEEP
 static int st_ahci_suspend(struct device *dev)
 {
-	struct st_ahci_drv_data *drv_data = dev_get_drvdata(dev);
-	struct ahci_host_priv *hpriv = drv_data->hpriv;
+	struct ata_host *host = dev_get_drvdata(dev);
+	struct ahci_host_priv *hpriv = host->private_data;
+	struct st_ahci_drv_data *drv_data = hpriv->plat_data;
 	int err;
 
 	err = ahci_platform_suspend_host(dev);
@@ -208,8 +211,8 @@ static int st_ahci_suspend(struct device *dev)
 
 static int st_ahci_resume(struct device *dev)
 {
-	struct st_ahci_drv_data *drv_data = dev_get_drvdata(dev);
-	struct ahci_host_priv *hpriv = drv_data->hpriv;
+	struct ata_host *host = dev_get_drvdata(dev);
+	struct ahci_host_priv *hpriv = host->private_data;
 	int err;
 
 	err = ahci_platform_enable_resources(hpriv);
-- 
1.9.1

Re: [PATCH] ata: ahci_st: fixup layering violations / drvdata errors

[Maxime Coquelin]

Hello Brian,

On 04/08/2015 08:59 PM, Brian Norris wrote:
> When working on another SATA driver that uses libahci_platform, I
> noticed an error in this driver; it tries to the the driver data for its
> device, while libata also thinks it can set the driver data. See:
>
>    ahci_platform_init_host()
>    -> ata_host_alloc_pinfo()
>       -> ata_host_alloc()
>          -> dev_set_drvdata()
>
> So instead of sticking the IP-specific platform data into drvdata, let's
> use the plat_data variable that is reserved for this use.
>
> Signed-off-by: Brian Norris <computersforpeace@gmail.com>
> Cc: Srinivas Kandagatla <srinivas.kandagatla@gmail.com>
> Cc: Maxime Coquelin <maxime.coquelin@st.com>
> Cc: Patrice Chotard <patrice.chotard@st.com>
> ---
> This is ONLY compile tested; I don't have hardware to run. This looks like it
> could have ramifications on suspend/resume support, and hot device removal
> (e.g., sysfs unbind), so it might qualify as -stable, if someone can test it
>
>   drivers/ata/ahci_st.c | 25 ++++++++++++++-----------
>   1 file changed, 14 insertions(+), 11 deletions(-)
>
>

Your patch looks sensible, thanks for spotting this issue.

Peter, do you have the SATA setup in place to test Brian's patch?

Once tested, you can add my:
Acked-by: Maxime Coquelin <maxime.coquelin@st.com>

Thanks,
Maxime

Re: [PATCH] ata: ahci_st: fixup layering violations / drvdata errors

[Sergei Shtylyov]

Hello.

On 4/8/2015 9:59 PM, Brian Norris wrote:

> When working on another SATA driver that uses libahci_platform, I
> noticed an error in this driver; it tries to the the driver data for its
> device, while libata also thinks it can set the driver data. See:

>    ahci_platform_init_host()
>    -> ata_host_alloc_pinfo()
>       -> ata_host_alloc()
>          -> dev_set_drvdata()

> So instead of sticking the IP-specific platform data into drvdata, let's
> use the plat_data variable that is reserved for this use.

> Signed-off-by: Brian Norris <computersforpeace@gmail.com>
> Cc: Srinivas Kandagatla <srinivas.kandagatla@gmail.com>
> Cc: Maxime Coquelin <maxime.coquelin@st.com>
> Cc: Patrice Chotard <patrice.chotard@st.com>
> ---
> This is ONLY compile tested; I don't have hardware to run. This looks like it
> could have ramifications on suspend/resume support, and hot device removal
> (e.g., sysfs unbind), so it might qualify as -stable, if someone can test it

>   drivers/ata/ahci_st.c | 25 ++++++++++++++-----------
>   1 file changed, 14 insertions(+), 11 deletions(-)

> diff --git a/drivers/ata/ahci_st.c b/drivers/ata/ahci_st.c
> index bc971af262e7..2bd2375c2ab1 100644
> --- a/drivers/ata/ahci_st.c
> +++ b/drivers/ata/ahci_st.c
[...]
> @@ -107,7 +108,9 @@ static void st_ahci_host_stop(struct ata_host *host)
>
>   static int st_ahci_probe_resets(struct platform_device *pdev)
>   {
> -	struct st_ahci_drv_data *drv_data = platform_get_drvdata(pdev);
> +	struct ata_host *host = dev_get_drvdata(&pdev->dev);

    Why not just platform_get_drvdata()?

[...]

MBR, Sergei

Re: [PATCH] ata: ahci_st: fixup layering violations / drvdata errors

[Peter Griffin]

Hi Maxime,

On Thu, 09 Apr 2015, Maxime Coquelin wrote:
> Hello Brian,
> 
<snip>
> >  drivers/ata/ahci_st.c | 25 ++++++++++++++-----------
> >  1 file changed, 14 insertions(+), 11 deletions(-)
> >
> >
> 
> Your patch looks sensible, thanks for spotting this issue.
> 
> Peter, do you have the SATA setup in place to test Brian's patch?

Yes I can test, although not until Saturday as I only have remote
access to the board today & tomorrow and the hard drive isn't
plugged in.

regards,

Peter.

Re: [PATCH] ata: ahci_st: fixup layering violations / drvdata errors

[Brian Norris]

On Thu, Apr 09, 2015 at 12:34:02PM +0300, Sergei Shtylyov wrote:
> Hello.
> 
> On 4/8/2015 9:59 PM, Brian Norris wrote:
> 
> >When working on another SATA driver that uses libahci_platform, I
> >noticed an error in this driver; it tries to the the driver data for its
> >device, while libata also thinks it can set the driver data. See:
> 
> >   ahci_platform_init_host()
> >   -> ata_host_alloc_pinfo()
> >      -> ata_host_alloc()
> >         -> dev_set_drvdata()
> 
> >So instead of sticking the IP-specific platform data into drvdata, let's
> >use the plat_data variable that is reserved for this use.
> 
> >Signed-off-by: Brian Norris <computersforpeace@gmail.com>
> >Cc: Srinivas Kandagatla <srinivas.kandagatla@gmail.com>
> >Cc: Maxime Coquelin <maxime.coquelin@st.com>
> >Cc: Patrice Chotard <patrice.chotard@st.com>
> >---
> >This is ONLY compile tested; I don't have hardware to run. This looks like it
> >could have ramifications on suspend/resume support, and hot device removal
> >(e.g., sysfs unbind), so it might qualify as -stable, if someone can test it
> 
> >  drivers/ata/ahci_st.c | 25 ++++++++++++++-----------
> >  1 file changed, 14 insertions(+), 11 deletions(-)
> 
> >diff --git a/drivers/ata/ahci_st.c b/drivers/ata/ahci_st.c
> >index bc971af262e7..2bd2375c2ab1 100644
> >--- a/drivers/ata/ahci_st.c
> >+++ b/drivers/ata/ahci_st.c
> [...]
> >@@ -107,7 +108,9 @@ static void st_ahci_host_stop(struct ata_host *host)
> >
> >  static int st_ahci_probe_resets(struct platform_device *pdev)
> >  {
> >-	struct st_ahci_drv_data *drv_data = platform_get_drvdata(pdev);
> >+	struct ata_host *host = dev_get_drvdata(&pdev->dev);
> 
>    Why not just platform_get_drvdata()?

Just being consistent, as that's what the rest of the driver uses. It
seems like it'd be easy to misconstrue dev_get_drvrdata(&pdev->dev) and
platform_get_drvdata(pdev) as two different things (e.g., when
grepping), when in fact they are the same. Seems like a needless source
of potential confusion.

Why should I use platform_get_drvdata()?

(NB: I didn't notice at first that the driver already was using
platform_get_drvdata(). I pretty much ignored anything that was already
there, since it was all wrong anyway.)

Anyway, I don't care either way, and in fact, I don't care about this
driver much at all as I never expect to use it; I just noticed the
defect when reading.

Brian

Re: [PATCH] ata: ahci_st: fixup layering violations / drvdata errors

[Tejun Heo]

On Thu, Apr 09, 2015 at 10:43:10AM +0100, Peter Griffin wrote:
> Yes I can test, although not until Saturday as I only have remote
> access to the board today & tomorrow and the hard drive isn't
> plugged in.

What's the status on this patch?  Should I push it through
for-4.1-fixes?

Thanks.

-- 
tejun

Re: [PATCH] ata: ahci_st: fixup layering violations / drvdata errors

[Peter Griffin]

Hi Tejun,

On Fri, 17 Apr 2015, Tejun Heo wrote:
> On Thu, Apr 09, 2015 at 10:43:10AM +0100, Peter Griffin wrote:
> > Yes I can test, although not until Saturday as I only have remote
> > access to the board today & tomorrow and the hard drive isn't
> > plugged in.
> 
> What's the status on this patch?  Should I push it through
> for-4.1-fixes?

The layering violation which Brian identified does need fixing. However
please don't take this patch as it currently is, as it causes a NULL
ptr dereference.

I can send an updated version in a moment which: -
1) Fixes the conflict you will get when applying it for v4.1
   (due to my "st_configure_oob must be called after IP is clocked" patch).

2) Fixes the crash which this patch introduces.

regards,

Peter.