[PATCH 0/2] fixes for yt8511 phy driver

[PATCH 0/2] fixes for yt8511 phy driver

[Peter Geis]

The Intel clang bot caught a few uninitialized variables in the new
Motorcomm driver. While investigating the issue, it was found that the
driver would have unintended effects when used in an unsupported mode.

Fixed the uninitialized ret variable and abort loading the driver in
unsupported modes.

Thank you to the Intel clang bot for catching these.

Peter Geis (2):
  net: phy: fix yt8511 clang uninitialized variable warning
  net: phy: abort loading yt8511 driver in unsupported modes

 drivers/net/phy/motorcomm.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

-- 
2.25.1

[PATCH 1/2] net: phy: fix yt8511 clang uninitialized variable warning

[Peter Geis]

clang doesn't preinitialize variables. If phy_select_page failed and
returned an error, phy_restore_page would be called with `ret` being
uninitialized.
Even though phy_restore_page won't use `ret` in this scenario,
initialize `ret` to silence the warning.

Fixes: b1b41c047f73 ("net: phy: add driver for Motorcomm yt8511 phy")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Geis <pgwipeout@gmail.com>
---
 drivers/net/phy/motorcomm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/phy/motorcomm.c b/drivers/net/phy/motorcomm.c
index 796b68f4b499..5795f446c528 100644
--- a/drivers/net/phy/motorcomm.c
+++ b/drivers/net/phy/motorcomm.c
@@ -51,7 +51,7 @@ static int yt8511_write_page(struct phy_device *phydev, int page)
 static int yt8511_config_init(struct phy_device *phydev)
 {
 	unsigned int ge, fe;
-	int ret, oldpage;
+	int oldpage, ret = 0;
 
 	/* set clock mode to 125mhz */
 	oldpage = phy_select_page(phydev, YT8511_EXT_CLK_GATE);
-- 
2.25.1

[PATCH 2/2] net: phy: abort loading yt8511 driver in unsupported modes

[Peter Geis]

While investigating the clang `ge` uninitialized variable report, it was
discovered the default switch would have unintended consequences. Due to
the switch to __phy_modify, the driver would modify the ID values in the
default scenario.

Fix this by promoting the interface mode switch and aborting when the
mode is not a supported RGMII mode.

This prevents the `ge` and `fe` variables from ever being used
uninitialized.

Fixes: b1b41c047f73 ("net: phy: add driver for Motorcomm yt8511 phy")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Geis <pgwipeout@gmail.com>
---
 drivers/net/phy/motorcomm.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/net/phy/motorcomm.c b/drivers/net/phy/motorcomm.c
index 5795f446c528..53178e978da7 100644
--- a/drivers/net/phy/motorcomm.c
+++ b/drivers/net/phy/motorcomm.c
@@ -53,15 +53,10 @@ static int yt8511_config_init(struct phy_device *phydev)
 	unsigned int ge, fe;
 	int oldpage, ret = 0;
 
-	/* set clock mode to 125mhz */
 	oldpage = phy_select_page(phydev, YT8511_EXT_CLK_GATE);
 	if (oldpage < 0)
 		goto err_restore_page;
 
-	ret = __phy_modify(phydev, YT8511_PAGE, 0, YT8511_CLK_125M);
-	if (ret < 0)
-		goto err_restore_page;
-
 	/* set rgmii delay mode */
 	switch (phydev->interface) {
 	case PHY_INTERFACE_MODE_RGMII:
@@ -80,14 +75,20 @@ static int yt8511_config_init(struct phy_device *phydev)
 		ge = YT8511_DELAY_RX | YT8511_DELAY_GE_TX_EN;
 		fe = YT8511_DELAY_FE_TX_EN;
 		break;
-	default: /* leave everything alone in other modes */
-		break;
+	default: /* do not support other modes */
+		ret = -EOPNOTSUPP;
+		goto err_restore_page;
 	}
 
 	ret = __phy_modify(phydev, YT8511_PAGE, (YT8511_DELAY_RX | YT8511_DELAY_GE_TX_EN), ge);
 	if (ret < 0)
 		goto err_restore_page;
 
+	/* set clock mode to 125mhz */
+	ret = __phy_modify(phydev, YT8511_PAGE, 0, YT8511_CLK_125M);
+	if (ret < 0)
+		goto err_restore_page;
+
 	/* fast ethernet delay is in a separate page */
 	ret = __phy_write(phydev, YT8511_PAGE_SELECT, YT8511_EXT_DELAY_DRIVE);
 	if (ret < 0)
-- 
2.25.1

Re: [PATCH 1/2] net: phy: fix yt8511 clang uninitialized variable warning

[Andrew Lunn]

On Tue, May 25, 2021 at 08:26:14AM -0400, Peter Geis wrote:
> clang doesn't preinitialize variables. If phy_select_page failed and
> returned an error, phy_restore_page would be called with `ret` being
> uninitialized.
> Even though phy_restore_page won't use `ret` in this scenario,
> initialize `ret` to silence the warning.
> 
> Fixes: b1b41c047f73 ("net: phy: add driver for Motorcomm yt8511 phy")
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Peter Geis <pgwipeout@gmail.com>
> ---
>  drivers/net/phy/motorcomm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/phy/motorcomm.c b/drivers/net/phy/motorcomm.c
> index 796b68f4b499..5795f446c528 100644
> --- a/drivers/net/phy/motorcomm.c
> +++ b/drivers/net/phy/motorcomm.c
> @@ -51,7 +51,7 @@ static int yt8511_write_page(struct phy_device *phydev, int page)
>  static int yt8511_config_init(struct phy_device *phydev)
>  {
>  	unsigned int ge, fe;
> -	int ret, oldpage;
> +	int oldpage, ret = 0;

Please keep to reverse Christmas tree.

With that fixed:

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

Re: [PATCH 2/2] net: phy: abort loading yt8511 driver in unsupported modes

[Andrew Lunn]

On Tue, May 25, 2021 at 08:26:15AM -0400, Peter Geis wrote:
> While investigating the clang `ge` uninitialized variable report, it was
> discovered the default switch would have unintended consequences. Due to
> the switch to __phy_modify, the driver would modify the ID values in the
> default scenario.
> 
> Fix this by promoting the interface mode switch and aborting when the
> mode is not a supported RGMII mode.
> 
> This prevents the `ge` and `fe` variables from ever being used
> uninitialized.
> 
> Fixes: b1b41c047f73 ("net: phy: add driver for Motorcomm yt8511 phy")
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Peter Geis <pgwipeout@gmail.com>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

Re: [PATCH 1/2] net: phy: fix yt8511 clang uninitialized variable warning

[Peter Geis]

On Tue, May 25, 2021 at 9:02 AM Andrew Lunn <andrew@lunn.ch> wrote:
>
> On Tue, May 25, 2021 at 08:26:14AM -0400, Peter Geis wrote:
> > clang doesn't preinitialize variables. If phy_select_page failed and
> > returned an error, phy_restore_page would be called with `ret` being
> > uninitialized.
> > Even though phy_restore_page won't use `ret` in this scenario,
> > initialize `ret` to silence the warning.
> >
> > Fixes: b1b41c047f73 ("net: phy: add driver for Motorcomm yt8511 phy")
> > Reported-by: kernel test robot <lkp@intel.com>
> > Signed-off-by: Peter Geis <pgwipeout@gmail.com>
> > ---
> >  drivers/net/phy/motorcomm.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/phy/motorcomm.c b/drivers/net/phy/motorcomm.c
> > index 796b68f4b499..5795f446c528 100644
> > --- a/drivers/net/phy/motorcomm.c
> > +++ b/drivers/net/phy/motorcomm.c
> > @@ -51,7 +51,7 @@ static int yt8511_write_page(struct phy_device *phydev, int page)
> >  static int yt8511_config_init(struct phy_device *phydev)
> >  {
> >       unsigned int ge, fe;
> > -     int ret, oldpage;
> > +     int oldpage, ret = 0;
>
> Please keep to reverse Christmas tree.

Ah, I missed that.
Do you want a v2 or will it be fixed on application?

>
> With that fixed:
>
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>
>
>     Andrew

Thanks!
Peter

Re: [PATCH 1/2] net: phy: fix yt8511 clang uninitialized variable warning

[Andrew Lunn]

> Do you want a v2 or will it be fixed on application?

A v2. And please remember to add the Reviewed-by tags.

  Andrew