[PATCH] extcon: fix extcon_get_extcon_dev() error handling

[PATCH] extcon: fix extcon_get_extcon_dev() error handling

[Dan Carpenter]

The extcon_get_extcon_dev() function returns error pointers on error
and NULL when it's a -EPROBE_DEFER defer situation.  There are eight
callers and only two of them handled this correctly.  In the other
callers an error pointer return would lead to a crash.

What prevents crashes is that errors can only happen in the case of
a bug in the caller or if CONFIG_EXTCON is disabled.  Six out of
eight callers use the Kconfig to either depend on or select
CONFIG_EXTCON.  Thus the real life impact of these bugs is tiny.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
The two callers where the drivers can be built without CONFIG_EXTCON
are TYPEC_FUSB302 and CHARGER_MAX8997.

If we apply this patch, it might be a good idea to send it to -stable
so that backported code that relies on handling error pointers does
not break silently.

 drivers/extcon/extcon.c                |  2 +-
 drivers/power/supply/axp288_charger.c  | 17 ++++++++++-------
 drivers/power/supply/charger-manager.c |  7 ++-----
 drivers/power/supply/max8997_charger.c | 10 +++++-----
 drivers/usb/dwc3/drd.c                 |  9 ++-------
 drivers/usb/phy/phy-omap-otg.c         |  4 ++--
 drivers/usb/typec/tcpm/fusb302.c       |  4 ++--
 drivers/extcon/extcon-axp288.c         |  4 ++--
 8 files changed, 26 insertions(+), 31 deletions(-)

diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
index e7a9561a826d..a35e99928807 100644
--- a/drivers/extcon/extcon.c
+++ b/drivers/extcon/extcon.c
@@ -876,7 +876,7 @@ struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name)
 		if (!strcmp(sd->name, extcon_name))
 			goto out;
 	}
-	sd = NULL;
+	sd = ERR_PTR(-EPROBE_DEFER);
 out:
 	mutex_unlock(&extcon_dev_list_lock);
 	return sd;
diff --git a/drivers/power/supply/axp288_charger.c b/drivers/power/supply/axp288_charger.c
index ec41f6cd3f93..4acfeb52a44e 100644
--- a/drivers/power/supply/axp288_charger.c
+++ b/drivers/power/supply/axp288_charger.c
@@ -848,17 +848,20 @@ static int axp288_charger_probe(struct platform_device *pdev)
 	info->regmap_irqc = axp20x->regmap_irqc;
 
 	info->cable.edev = extcon_get_extcon_dev(AXP288_EXTCON_DEV_NAME);
-	if (info->cable.edev == NULL) {
-		dev_dbg(dev, "%s is not ready, probe deferred\n",
-			AXP288_EXTCON_DEV_NAME);
-		return -EPROBE_DEFER;
+	if (IS_ERR(info->cable.edev)) {
+		dev_err_probe(dev, PTR_ERR(info->cable.edev),
+			      "extcon_get_extcon_dev(%s) failed\n",
+			      AXP288_EXTCON_DEV_NAME);
+		return PTR_ERR(info->cable.edev);
 	}
 
 	if (acpi_dev_present(USB_HOST_EXTCON_HID, NULL, -1)) {
 		info->otg.cable = extcon_get_extcon_dev(USB_HOST_EXTCON_NAME);
-		if (info->otg.cable == NULL) {
-			dev_dbg(dev, "EXTCON_USB_HOST is not ready, probe deferred\n");
-			return -EPROBE_DEFER;
+		if (IS_ERR(info->otg.cable)) {
+			dev_err_probe(dev, PTR_ERR(info->otg.cable),
+				      "extcon_get_extcon_dev(%s) failed\n",
+				      USB_HOST_EXTCON_NAME);
+			return PTR_ERR(info->otg.cable);
 		}
 		dev_info(dev, "Using " USB_HOST_EXTCON_HID " extcon for usb-id\n");
 	}
diff --git a/drivers/power/supply/charger-manager.c b/drivers/power/supply/charger-manager.c
index d67edb760c94..92db79400a6a 100644
--- a/drivers/power/supply/charger-manager.c
+++ b/drivers/power/supply/charger-manager.c
@@ -985,13 +985,10 @@ static int charger_extcon_init(struct charger_manager *cm,
 	cable->nb.notifier_call = charger_extcon_notifier;
 
 	cable->extcon_dev = extcon_get_extcon_dev(cable->extcon_name);
-	if (IS_ERR_OR_NULL(cable->extcon_dev)) {
+	if (IS_ERR(cable->extcon_dev)) {
 		pr_err("Cannot find extcon_dev for %s (cable: %s)\n",
 			cable->extcon_name, cable->name);
-		if (cable->extcon_dev == NULL)
-			return -EPROBE_DEFER;
-		else
-			return PTR_ERR(cable->extcon_dev);
+		return PTR_ERR(cable->extcon_dev);
 	}
 
 	for (i = 0; i < ARRAY_SIZE(extcon_mapping); i++) {
diff --git a/drivers/power/supply/max8997_charger.c b/drivers/power/supply/max8997_charger.c
index 25207fe2aa68..634658adf313 100644
--- a/drivers/power/supply/max8997_charger.c
+++ b/drivers/power/supply/max8997_charger.c
@@ -248,13 +248,13 @@ static int max8997_battery_probe(struct platform_device *pdev)
 		dev_info(&pdev->dev, "couldn't get charger regulator\n");
 	}
 	charger->edev = extcon_get_extcon_dev("max8997-muic");
-	if (IS_ERR_OR_NULL(charger->edev)) {
-		if (!charger->edev)
-			return -EPROBE_DEFER;
-		dev_info(charger->dev, "couldn't get extcon device\n");
+	if (IS_ERR(charger->edev)) {
+		dev_err_probe(charger->dev, PTR_ERR(charger->edev),
+			      "couldn't get extcon device: max8997-muic\n");
+		return PTR_ERR(charger->edev);
 	}
 
-	if (!IS_ERR(charger->reg) && !IS_ERR_OR_NULL(charger->edev)) {
+	if (!IS_ERR(charger->reg)) {
 		INIT_WORK(&charger->extcon_work, max8997_battery_extcon_evt_worker);
 		ret = devm_add_action(&pdev->dev, max8997_battery_extcon_evt_stop_work, charger);
 		if (ret) {
diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
index d7f76835137f..a490f79131c1 100644
--- a/drivers/usb/dwc3/drd.c
+++ b/drivers/usb/dwc3/drd.c
@@ -454,13 +454,8 @@ static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
 	 * This device property is for kernel internal use only and
 	 * is expected to be set by the glue code.
 	 */
-	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
-		edev = extcon_get_extcon_dev(name);
-		if (!edev)
-			return ERR_PTR(-EPROBE_DEFER);
-
-		return edev;
-	}
+	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0)
+		return extcon_get_extcon_dev(name);
 
 	/*
 	 * Try to get an extcon device from the USB PHY controller's "port"
diff --git a/drivers/usb/phy/phy-omap-otg.c b/drivers/usb/phy/phy-omap-otg.c
index ee0863c6553e..6e6ef8c0bc7e 100644
--- a/drivers/usb/phy/phy-omap-otg.c
+++ b/drivers/usb/phy/phy-omap-otg.c
@@ -95,8 +95,8 @@ static int omap_otg_probe(struct platform_device *pdev)
 		return -ENODEV;
 
 	extcon = extcon_get_extcon_dev(config->extcon);
-	if (!extcon)
-		return -EPROBE_DEFER;
+	if (IS_ERR(extcon))
+		return PTR_ERR(extcon);
 
 	otg_dev = devm_kzalloc(&pdev->dev, sizeof(*otg_dev), GFP_KERNEL);
 	if (!otg_dev)
diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
index 7a2a17866a82..8594b59bd527 100644
--- a/drivers/usb/typec/tcpm/fusb302.c
+++ b/drivers/usb/typec/tcpm/fusb302.c
@@ -1706,8 +1706,8 @@ static int fusb302_probe(struct i2c_client *client,
 	 */
 	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
 		chip->extcon = extcon_get_extcon_dev(name);
-		if (!chip->extcon)
-			return -EPROBE_DEFER;
+		if (IS_ERR(chip->extcon))
+			return PTR_ERR(chip->extcon);
 	}
 
 	chip->vbus = devm_regulator_get(chip->dev, "vbus");
diff --git a/drivers/extcon/extcon-axp288.c b/drivers/extcon/extcon-axp288.c
index 7c6d5857ff25..180be768c215 100644
--- a/drivers/extcon/extcon-axp288.c
+++ b/drivers/extcon/extcon-axp288.c
@@ -394,8 +394,8 @@ static int axp288_extcon_probe(struct platform_device *pdev)
 		if (adev) {
 			info->id_extcon = extcon_get_extcon_dev(acpi_dev_name(adev));
 			put_device(&adev->dev);
-			if (!info->id_extcon)
-				return -EPROBE_DEFER;
+			if (IS_ERR(info->id_extcon))
+				return PTR_ERR(info->id_extcon);
 
 			dev_info(dev, "controlling USB role\n");
 		} else {
-- 
2.20.1

Re: [PATCH] extcon: fix extcon_get_extcon_dev() error handling

[Sebastian Reichel]

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Hi,

On Thu, Nov 18, 2021 at 02:32:22PM +0300, Dan Carpenter wrote:
> The extcon_get_extcon_dev() function returns error pointers on error
> and NULL when it's a -EPROBE_DEFER defer situation.  There are eight
> callers and only two of them handled this correctly.  In the other
> callers an error pointer return would lead to a crash.
> 
> What prevents crashes is that errors can only happen in the case of
> a bug in the caller or if CONFIG_EXTCON is disabled.  Six out of
> eight callers use the Kconfig to either depend on or select
> CONFIG_EXTCON.  Thus the real life impact of these bugs is tiny.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> The two callers where the drivers can be built without CONFIG_EXTCON
> are TYPEC_FUSB302 and CHARGER_MAX8997.
> 
> If we apply this patch, it might be a good idea to send it to -stable
> so that backported code that relies on handling error pointers does
> not break silently.
> 
>  drivers/extcon/extcon.c                |  2 +-
>  drivers/power/supply/axp288_charger.c  | 17 ++++++++++-------
>  drivers/power/supply/charger-manager.c |  7 ++-----
>  drivers/power/supply/max8997_charger.c | 10 +++++-----
>  drivers/usb/dwc3/drd.c                 |  9 ++-------
>  drivers/usb/phy/phy-omap-otg.c         |  4 ++--
>  drivers/usb/typec/tcpm/fusb302.c       |  4 ++--
>  drivers/extcon/extcon-axp288.c         |  4 ++--
>  8 files changed, 26 insertions(+), 31 deletions(-)

Acked-by: Sebastian Reichel <sebastian.reichel@collabora.com> # for power-supply

-- Sebastian

> 
> diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
> index e7a9561a826d..a35e99928807 100644
> --- a/drivers/extcon/extcon.c
> +++ b/drivers/extcon/extcon.c
> @@ -876,7 +876,7 @@ struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name)
>  		if (!strcmp(sd->name, extcon_name))
>  			goto out;
>  	}
> -	sd = NULL;
> +	sd = ERR_PTR(-EPROBE_DEFER);
>  out:
>  	mutex_unlock(&extcon_dev_list_lock);
>  	return sd;
> diff --git a/drivers/power/supply/axp288_charger.c b/drivers/power/supply/axp288_charger.c
> index ec41f6cd3f93..4acfeb52a44e 100644
> --- a/drivers/power/supply/axp288_charger.c
> +++ b/drivers/power/supply/axp288_charger.c
> @@ -848,17 +848,20 @@ static int axp288_charger_probe(struct platform_device *pdev)
>  	info->regmap_irqc = axp20x->regmap_irqc;
>  
>  	info->cable.edev = extcon_get_extcon_dev(AXP288_EXTCON_DEV_NAME);
> -	if (info->cable.edev == NULL) {
> -		dev_dbg(dev, "%s is not ready, probe deferred\n",
> -			AXP288_EXTCON_DEV_NAME);
> -		return -EPROBE_DEFER;
> +	if (IS_ERR(info->cable.edev)) {
> +		dev_err_probe(dev, PTR_ERR(info->cable.edev),
> +			      "extcon_get_extcon_dev(%s) failed\n",
> +			      AXP288_EXTCON_DEV_NAME);
> +		return PTR_ERR(info->cable.edev);
>  	}
>  
>  	if (acpi_dev_present(USB_HOST_EXTCON_HID, NULL, -1)) {
>  		info->otg.cable = extcon_get_extcon_dev(USB_HOST_EXTCON_NAME);
> -		if (info->otg.cable == NULL) {
> -			dev_dbg(dev, "EXTCON_USB_HOST is not ready, probe deferred\n");
> -			return -EPROBE_DEFER;
> +		if (IS_ERR(info->otg.cable)) {
> +			dev_err_probe(dev, PTR_ERR(info->otg.cable),
> +				      "extcon_get_extcon_dev(%s) failed\n",
> +				      USB_HOST_EXTCON_NAME);
> +			return PTR_ERR(info->otg.cable);
>  		}
>  		dev_info(dev, "Using " USB_HOST_EXTCON_HID " extcon for usb-id\n");
>  	}
> diff --git a/drivers/power/supply/charger-manager.c b/drivers/power/supply/charger-manager.c
> index d67edb760c94..92db79400a6a 100644
> --- a/drivers/power/supply/charger-manager.c
> +++ b/drivers/power/supply/charger-manager.c
> @@ -985,13 +985,10 @@ static int charger_extcon_init(struct charger_manager *cm,
>  	cable->nb.notifier_call = charger_extcon_notifier;
>  
>  	cable->extcon_dev = extcon_get_extcon_dev(cable->extcon_name);
> -	if (IS_ERR_OR_NULL(cable->extcon_dev)) {
> +	if (IS_ERR(cable->extcon_dev)) {
>  		pr_err("Cannot find extcon_dev for %s (cable: %s)\n",
>  			cable->extcon_name, cable->name);
> -		if (cable->extcon_dev == NULL)
> -			return -EPROBE_DEFER;
> -		else
> -			return PTR_ERR(cable->extcon_dev);
> +		return PTR_ERR(cable->extcon_dev);
>  	}
>  
>  	for (i = 0; i < ARRAY_SIZE(extcon_mapping); i++) {
> diff --git a/drivers/power/supply/max8997_charger.c b/drivers/power/supply/max8997_charger.c
> index 25207fe2aa68..634658adf313 100644
> --- a/drivers/power/supply/max8997_charger.c
> +++ b/drivers/power/supply/max8997_charger.c
> @@ -248,13 +248,13 @@ static int max8997_battery_probe(struct platform_device *pdev)
>  		dev_info(&pdev->dev, "couldn't get charger regulator\n");
>  	}
>  	charger->edev = extcon_get_extcon_dev("max8997-muic");
> -	if (IS_ERR_OR_NULL(charger->edev)) {
> -		if (!charger->edev)
> -			return -EPROBE_DEFER;
> -		dev_info(charger->dev, "couldn't get extcon device\n");
> +	if (IS_ERR(charger->edev)) {
> +		dev_err_probe(charger->dev, PTR_ERR(charger->edev),
> +			      "couldn't get extcon device: max8997-muic\n");
> +		return PTR_ERR(charger->edev);
>  	}
>  
> -	if (!IS_ERR(charger->reg) && !IS_ERR_OR_NULL(charger->edev)) {
> +	if (!IS_ERR(charger->reg)) {
>  		INIT_WORK(&charger->extcon_work, max8997_battery_extcon_evt_worker);
>  		ret = devm_add_action(&pdev->dev, max8997_battery_extcon_evt_stop_work, charger);
>  		if (ret) {
> diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
> index d7f76835137f..a490f79131c1 100644
> --- a/drivers/usb/dwc3/drd.c
> +++ b/drivers/usb/dwc3/drd.c
> @@ -454,13 +454,8 @@ static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
>  	 * This device property is for kernel internal use only and
>  	 * is expected to be set by the glue code.
>  	 */
> -	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
> -		edev = extcon_get_extcon_dev(name);
> -		if (!edev)
> -			return ERR_PTR(-EPROBE_DEFER);
> -
> -		return edev;
> -	}
> +	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0)
> +		return extcon_get_extcon_dev(name);
>  
>  	/*
>  	 * Try to get an extcon device from the USB PHY controller's "port"
> diff --git a/drivers/usb/phy/phy-omap-otg.c b/drivers/usb/phy/phy-omap-otg.c
> index ee0863c6553e..6e6ef8c0bc7e 100644
> --- a/drivers/usb/phy/phy-omap-otg.c
> +++ b/drivers/usb/phy/phy-omap-otg.c
> @@ -95,8 +95,8 @@ static int omap_otg_probe(struct platform_device *pdev)
>  		return -ENODEV;
>  
>  	extcon = extcon_get_extcon_dev(config->extcon);
> -	if (!extcon)
> -		return -EPROBE_DEFER;
> +	if (IS_ERR(extcon))
> +		return PTR_ERR(extcon);
>  
>  	otg_dev = devm_kzalloc(&pdev->dev, sizeof(*otg_dev), GFP_KERNEL);
>  	if (!otg_dev)
> diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> index 7a2a17866a82..8594b59bd527 100644
> --- a/drivers/usb/typec/tcpm/fusb302.c
> +++ b/drivers/usb/typec/tcpm/fusb302.c
> @@ -1706,8 +1706,8 @@ static int fusb302_probe(struct i2c_client *client,
>  	 */
>  	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
>  		chip->extcon = extcon_get_extcon_dev(name);
> -		if (!chip->extcon)
> -			return -EPROBE_DEFER;
> +		if (IS_ERR(chip->extcon))
> +			return PTR_ERR(chip->extcon);
>  	}
>  
>  	chip->vbus = devm_regulator_get(chip->dev, "vbus");
> diff --git a/drivers/extcon/extcon-axp288.c b/drivers/extcon/extcon-axp288.c
> index 7c6d5857ff25..180be768c215 100644
> --- a/drivers/extcon/extcon-axp288.c
> +++ b/drivers/extcon/extcon-axp288.c
> @@ -394,8 +394,8 @@ static int axp288_extcon_probe(struct platform_device *pdev)
>  		if (adev) {
>  			info->id_extcon = extcon_get_extcon_dev(acpi_dev_name(adev));
>  			put_device(&adev->dev);
> -			if (!info->id_extcon)
> -				return -EPROBE_DEFER;
> +			if (IS_ERR(info->id_extcon))
> +				return PTR_ERR(info->id_extcon);
>  
>  			dev_info(dev, "controlling USB role\n");
>  		} else {
> -- 
> 2.20.1
> 

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Re: [PATCH] extcon: fix extcon_get_extcon_dev() error handling

[Hans de Goede]

Hi,

On 11/18/21 12:32, Dan Carpenter wrote:
> The extcon_get_extcon_dev() function returns error pointers on error
> and NULL when it's a -EPROBE_DEFER defer situation.  There are eight
> callers and only two of them handled this correctly.  In the other
> callers an error pointer return would lead to a crash.
> 
> What prevents crashes is that errors can only happen in the case of
> a bug in the caller or if CONFIG_EXTCON is disabled.  Six out of
> eight callers use the Kconfig to either depend on or select
> CONFIG_EXTCON.  Thus the real life impact of these bugs is tiny.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Thanks, patch looks good to me:

Reviewed-by: Hans de Goede <hdegoede@redhat.com>

Regards,

Hans


> ---
> The two callers where the drivers can be built without CONFIG_EXTCON
> are TYPEC_FUSB302 and CHARGER_MAX8997.
> 
> If we apply this patch, it might be a good idea to send it to -stable
> so that backported code that relies on handling error pointers does
> not break silently.
> 
>  drivers/extcon/extcon.c                |  2 +-
>  drivers/power/supply/axp288_charger.c  | 17 ++++++++++-------
>  drivers/power/supply/charger-manager.c |  7 ++-----
>  drivers/power/supply/max8997_charger.c | 10 +++++-----
>  drivers/usb/dwc3/drd.c                 |  9 ++-------
>  drivers/usb/phy/phy-omap-otg.c         |  4 ++--
>  drivers/usb/typec/tcpm/fusb302.c       |  4 ++--
>  drivers/extcon/extcon-axp288.c         |  4 ++--
>  8 files changed, 26 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
> index e7a9561a826d..a35e99928807 100644
> --- a/drivers/extcon/extcon.c
> +++ b/drivers/extcon/extcon.c
> @@ -876,7 +876,7 @@ struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name)
>  		if (!strcmp(sd->name, extcon_name))
>  			goto out;
>  	}
> -	sd = NULL;
> +	sd = ERR_PTR(-EPROBE_DEFER);
>  out:
>  	mutex_unlock(&extcon_dev_list_lock);
>  	return sd;
> diff --git a/drivers/power/supply/axp288_charger.c b/drivers/power/supply/axp288_charger.c
> index ec41f6cd3f93..4acfeb52a44e 100644
> --- a/drivers/power/supply/axp288_charger.c
> +++ b/drivers/power/supply/axp288_charger.c
> @@ -848,17 +848,20 @@ static int axp288_charger_probe(struct platform_device *pdev)
>  	info->regmap_irqc = axp20x->regmap_irqc;
>  
>  	info->cable.edev = extcon_get_extcon_dev(AXP288_EXTCON_DEV_NAME);
> -	if (info->cable.edev == NULL) {
> -		dev_dbg(dev, "%s is not ready, probe deferred\n",
> -			AXP288_EXTCON_DEV_NAME);
> -		return -EPROBE_DEFER;
> +	if (IS_ERR(info->cable.edev)) {
> +		dev_err_probe(dev, PTR_ERR(info->cable.edev),
> +			      "extcon_get_extcon_dev(%s) failed\n",
> +			      AXP288_EXTCON_DEV_NAME);
> +		return PTR_ERR(info->cable.edev);
>  	}
>  
>  	if (acpi_dev_present(USB_HOST_EXTCON_HID, NULL, -1)) {
>  		info->otg.cable = extcon_get_extcon_dev(USB_HOST_EXTCON_NAME);
> -		if (info->otg.cable == NULL) {
> -			dev_dbg(dev, "EXTCON_USB_HOST is not ready, probe deferred\n");
> -			return -EPROBE_DEFER;
> +		if (IS_ERR(info->otg.cable)) {
> +			dev_err_probe(dev, PTR_ERR(info->otg.cable),
> +				      "extcon_get_extcon_dev(%s) failed\n",
> +				      USB_HOST_EXTCON_NAME);
> +			return PTR_ERR(info->otg.cable);
>  		}
>  		dev_info(dev, "Using " USB_HOST_EXTCON_HID " extcon for usb-id\n");
>  	}
> diff --git a/drivers/power/supply/charger-manager.c b/drivers/power/supply/charger-manager.c
> index d67edb760c94..92db79400a6a 100644
> --- a/drivers/power/supply/charger-manager.c
> +++ b/drivers/power/supply/charger-manager.c
> @@ -985,13 +985,10 @@ static int charger_extcon_init(struct charger_manager *cm,
>  	cable->nb.notifier_call = charger_extcon_notifier;
>  
>  	cable->extcon_dev = extcon_get_extcon_dev(cable->extcon_name);
> -	if (IS_ERR_OR_NULL(cable->extcon_dev)) {
> +	if (IS_ERR(cable->extcon_dev)) {
>  		pr_err("Cannot find extcon_dev for %s (cable: %s)\n",
>  			cable->extcon_name, cable->name);
> -		if (cable->extcon_dev == NULL)
> -			return -EPROBE_DEFER;
> -		else
> -			return PTR_ERR(cable->extcon_dev);
> +		return PTR_ERR(cable->extcon_dev);
>  	}
>  
>  	for (i = 0; i < ARRAY_SIZE(extcon_mapping); i++) {
> diff --git a/drivers/power/supply/max8997_charger.c b/drivers/power/supply/max8997_charger.c
> index 25207fe2aa68..634658adf313 100644
> --- a/drivers/power/supply/max8997_charger.c
> +++ b/drivers/power/supply/max8997_charger.c
> @@ -248,13 +248,13 @@ static int max8997_battery_probe(struct platform_device *pdev)
>  		dev_info(&pdev->dev, "couldn't get charger regulator\n");
>  	}
>  	charger->edev = extcon_get_extcon_dev("max8997-muic");
> -	if (IS_ERR_OR_NULL(charger->edev)) {
> -		if (!charger->edev)
> -			return -EPROBE_DEFER;
> -		dev_info(charger->dev, "couldn't get extcon device\n");
> +	if (IS_ERR(charger->edev)) {
> +		dev_err_probe(charger->dev, PTR_ERR(charger->edev),
> +			      "couldn't get extcon device: max8997-muic\n");
> +		return PTR_ERR(charger->edev);
>  	}
>  
> -	if (!IS_ERR(charger->reg) && !IS_ERR_OR_NULL(charger->edev)) {
> +	if (!IS_ERR(charger->reg)) {
>  		INIT_WORK(&charger->extcon_work, max8997_battery_extcon_evt_worker);
>  		ret = devm_add_action(&pdev->dev, max8997_battery_extcon_evt_stop_work, charger);
>  		if (ret) {
> diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
> index d7f76835137f..a490f79131c1 100644
> --- a/drivers/usb/dwc3/drd.c
> +++ b/drivers/usb/dwc3/drd.c
> @@ -454,13 +454,8 @@ static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
>  	 * This device property is for kernel internal use only and
>  	 * is expected to be set by the glue code.
>  	 */
> -	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
> -		edev = extcon_get_extcon_dev(name);
> -		if (!edev)
> -			return ERR_PTR(-EPROBE_DEFER);
> -
> -		return edev;
> -	}
> +	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0)
> +		return extcon_get_extcon_dev(name);
>  
>  	/*
>  	 * Try to get an extcon device from the USB PHY controller's "port"
> diff --git a/drivers/usb/phy/phy-omap-otg.c b/drivers/usb/phy/phy-omap-otg.c
> index ee0863c6553e..6e6ef8c0bc7e 100644
> --- a/drivers/usb/phy/phy-omap-otg.c
> +++ b/drivers/usb/phy/phy-omap-otg.c
> @@ -95,8 +95,8 @@ static int omap_otg_probe(struct platform_device *pdev)
>  		return -ENODEV;
>  
>  	extcon = extcon_get_extcon_dev(config->extcon);
> -	if (!extcon)
> -		return -EPROBE_DEFER;
> +	if (IS_ERR(extcon))
> +		return PTR_ERR(extcon);
>  
>  	otg_dev = devm_kzalloc(&pdev->dev, sizeof(*otg_dev), GFP_KERNEL);
>  	if (!otg_dev)
> diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> index 7a2a17866a82..8594b59bd527 100644
> --- a/drivers/usb/typec/tcpm/fusb302.c
> +++ b/drivers/usb/typec/tcpm/fusb302.c
> @@ -1706,8 +1706,8 @@ static int fusb302_probe(struct i2c_client *client,
>  	 */
>  	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
>  		chip->extcon = extcon_get_extcon_dev(name);
> -		if (!chip->extcon)
> -			return -EPROBE_DEFER;
> +		if (IS_ERR(chip->extcon))
> +			return PTR_ERR(chip->extcon);
>  	}
>  
>  	chip->vbus = devm_regulator_get(chip->dev, "vbus");
> diff --git a/drivers/extcon/extcon-axp288.c b/drivers/extcon/extcon-axp288.c
> index 7c6d5857ff25..180be768c215 100644
> --- a/drivers/extcon/extcon-axp288.c
> +++ b/drivers/extcon/extcon-axp288.c
> @@ -394,8 +394,8 @@ static int axp288_extcon_probe(struct platform_device *pdev)
>  		if (adev) {
>  			info->id_extcon = extcon_get_extcon_dev(acpi_dev_name(adev));
>  			put_device(&adev->dev);
> -			if (!info->id_extcon)
> -				return -EPROBE_DEFER;
> +			if (IS_ERR(info->id_extcon))
> +				return PTR_ERR(info->id_extcon);
>  
>  			dev_info(dev, "controlling USB role\n");
>  		} else {
> 

Re: [PATCH] extcon: fix extcon_get_extcon_dev() error handling

[Heikki Krogerus]

On Thu, Nov 18, 2021 at 02:32:22PM +0300, Dan Carpenter wrote:
> The extcon_get_extcon_dev() function returns error pointers on error
> and NULL when it's a -EPROBE_DEFER defer situation.  There are eight
> callers and only two of them handled this correctly.  In the other
> callers an error pointer return would lead to a crash.
> 
> What prevents crashes is that errors can only happen in the case of
> a bug in the caller or if CONFIG_EXTCON is disabled.  Six out of
> eight callers use the Kconfig to either depend on or select
> CONFIG_EXTCON.  Thus the real life impact of these bugs is tiny.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
> The two callers where the drivers can be built without CONFIG_EXTCON
> are TYPEC_FUSB302 and CHARGER_MAX8997.
> 
> If we apply this patch, it might be a good idea to send it to -stable
> so that backported code that relies on handling error pointers does
> not break silently.
> 
>  drivers/extcon/extcon.c                |  2 +-
>  drivers/power/supply/axp288_charger.c  | 17 ++++++++++-------
>  drivers/power/supply/charger-manager.c |  7 ++-----
>  drivers/power/supply/max8997_charger.c | 10 +++++-----
>  drivers/usb/dwc3/drd.c                 |  9 ++-------
>  drivers/usb/phy/phy-omap-otg.c         |  4 ++--
>  drivers/usb/typec/tcpm/fusb302.c       |  4 ++--
>  drivers/extcon/extcon-axp288.c         |  4 ++--
>  8 files changed, 26 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
> index e7a9561a826d..a35e99928807 100644
> --- a/drivers/extcon/extcon.c
> +++ b/drivers/extcon/extcon.c
> @@ -876,7 +876,7 @@ struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name)
>  		if (!strcmp(sd->name, extcon_name))
>  			goto out;
>  	}
> -	sd = NULL;
> +	sd = ERR_PTR(-EPROBE_DEFER);
>  out:
>  	mutex_unlock(&extcon_dev_list_lock);
>  	return sd;
> diff --git a/drivers/power/supply/axp288_charger.c b/drivers/power/supply/axp288_charger.c
> index ec41f6cd3f93..4acfeb52a44e 100644
> --- a/drivers/power/supply/axp288_charger.c
> +++ b/drivers/power/supply/axp288_charger.c
> @@ -848,17 +848,20 @@ static int axp288_charger_probe(struct platform_device *pdev)
>  	info->regmap_irqc = axp20x->regmap_irqc;
>  
>  	info->cable.edev = extcon_get_extcon_dev(AXP288_EXTCON_DEV_NAME);
> -	if (info->cable.edev == NULL) {
> -		dev_dbg(dev, "%s is not ready, probe deferred\n",
> -			AXP288_EXTCON_DEV_NAME);
> -		return -EPROBE_DEFER;
> +	if (IS_ERR(info->cable.edev)) {
> +		dev_err_probe(dev, PTR_ERR(info->cable.edev),
> +			      "extcon_get_extcon_dev(%s) failed\n",
> +			      AXP288_EXTCON_DEV_NAME);
> +		return PTR_ERR(info->cable.edev);
>  	}
>  
>  	if (acpi_dev_present(USB_HOST_EXTCON_HID, NULL, -1)) {
>  		info->otg.cable = extcon_get_extcon_dev(USB_HOST_EXTCON_NAME);
> -		if (info->otg.cable == NULL) {
> -			dev_dbg(dev, "EXTCON_USB_HOST is not ready, probe deferred\n");
> -			return -EPROBE_DEFER;
> +		if (IS_ERR(info->otg.cable)) {
> +			dev_err_probe(dev, PTR_ERR(info->otg.cable),
> +				      "extcon_get_extcon_dev(%s) failed\n",
> +				      USB_HOST_EXTCON_NAME);
> +			return PTR_ERR(info->otg.cable);
>  		}
>  		dev_info(dev, "Using " USB_HOST_EXTCON_HID " extcon for usb-id\n");
>  	}
> diff --git a/drivers/power/supply/charger-manager.c b/drivers/power/supply/charger-manager.c
> index d67edb760c94..92db79400a6a 100644
> --- a/drivers/power/supply/charger-manager.c
> +++ b/drivers/power/supply/charger-manager.c
> @@ -985,13 +985,10 @@ static int charger_extcon_init(struct charger_manager *cm,
>  	cable->nb.notifier_call = charger_extcon_notifier;
>  
>  	cable->extcon_dev = extcon_get_extcon_dev(cable->extcon_name);
> -	if (IS_ERR_OR_NULL(cable->extcon_dev)) {
> +	if (IS_ERR(cable->extcon_dev)) {
>  		pr_err("Cannot find extcon_dev for %s (cable: %s)\n",
>  			cable->extcon_name, cable->name);
> -		if (cable->extcon_dev == NULL)
> -			return -EPROBE_DEFER;
> -		else
> -			return PTR_ERR(cable->extcon_dev);
> +		return PTR_ERR(cable->extcon_dev);
>  	}
>  
>  	for (i = 0; i < ARRAY_SIZE(extcon_mapping); i++) {
> diff --git a/drivers/power/supply/max8997_charger.c b/drivers/power/supply/max8997_charger.c
> index 25207fe2aa68..634658adf313 100644
> --- a/drivers/power/supply/max8997_charger.c
> +++ b/drivers/power/supply/max8997_charger.c
> @@ -248,13 +248,13 @@ static int max8997_battery_probe(struct platform_device *pdev)
>  		dev_info(&pdev->dev, "couldn't get charger regulator\n");
>  	}
>  	charger->edev = extcon_get_extcon_dev("max8997-muic");
> -	if (IS_ERR_OR_NULL(charger->edev)) {
> -		if (!charger->edev)
> -			return -EPROBE_DEFER;
> -		dev_info(charger->dev, "couldn't get extcon device\n");
> +	if (IS_ERR(charger->edev)) {
> +		dev_err_probe(charger->dev, PTR_ERR(charger->edev),
> +			      "couldn't get extcon device: max8997-muic\n");
> +		return PTR_ERR(charger->edev);
>  	}
>  
> -	if (!IS_ERR(charger->reg) && !IS_ERR_OR_NULL(charger->edev)) {
> +	if (!IS_ERR(charger->reg)) {
>  		INIT_WORK(&charger->extcon_work, max8997_battery_extcon_evt_worker);
>  		ret = devm_add_action(&pdev->dev, max8997_battery_extcon_evt_stop_work, charger);
>  		if (ret) {
> diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
> index d7f76835137f..a490f79131c1 100644
> --- a/drivers/usb/dwc3/drd.c
> +++ b/drivers/usb/dwc3/drd.c
> @@ -454,13 +454,8 @@ static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
>  	 * This device property is for kernel internal use only and
>  	 * is expected to be set by the glue code.
>  	 */
> -	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
> -		edev = extcon_get_extcon_dev(name);
> -		if (!edev)
> -			return ERR_PTR(-EPROBE_DEFER);
> -
> -		return edev;
> -	}
> +	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0)
> +		return extcon_get_extcon_dev(name);
>  
>  	/*
>  	 * Try to get an extcon device from the USB PHY controller's "port"
> diff --git a/drivers/usb/phy/phy-omap-otg.c b/drivers/usb/phy/phy-omap-otg.c
> index ee0863c6553e..6e6ef8c0bc7e 100644
> --- a/drivers/usb/phy/phy-omap-otg.c
> +++ b/drivers/usb/phy/phy-omap-otg.c
> @@ -95,8 +95,8 @@ static int omap_otg_probe(struct platform_device *pdev)
>  		return -ENODEV;
>  
>  	extcon = extcon_get_extcon_dev(config->extcon);
> -	if (!extcon)
> -		return -EPROBE_DEFER;
> +	if (IS_ERR(extcon))
> +		return PTR_ERR(extcon);
>  
>  	otg_dev = devm_kzalloc(&pdev->dev, sizeof(*otg_dev), GFP_KERNEL);
>  	if (!otg_dev)
> diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> index 7a2a17866a82..8594b59bd527 100644
> --- a/drivers/usb/typec/tcpm/fusb302.c
> +++ b/drivers/usb/typec/tcpm/fusb302.c
> @@ -1706,8 +1706,8 @@ static int fusb302_probe(struct i2c_client *client,
>  	 */
>  	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
>  		chip->extcon = extcon_get_extcon_dev(name);
> -		if (!chip->extcon)
> -			return -EPROBE_DEFER;
> +		if (IS_ERR(chip->extcon))
> +			return PTR_ERR(chip->extcon);
>  	}
>  
>  	chip->vbus = devm_regulator_get(chip->dev, "vbus");
> diff --git a/drivers/extcon/extcon-axp288.c b/drivers/extcon/extcon-axp288.c
> index 7c6d5857ff25..180be768c215 100644
> --- a/drivers/extcon/extcon-axp288.c
> +++ b/drivers/extcon/extcon-axp288.c
> @@ -394,8 +394,8 @@ static int axp288_extcon_probe(struct platform_device *pdev)
>  		if (adev) {
>  			info->id_extcon = extcon_get_extcon_dev(acpi_dev_name(adev));
>  			put_device(&adev->dev);
> -			if (!info->id_extcon)
> -				return -EPROBE_DEFER;
> +			if (IS_ERR(info->id_extcon))
> +				return PTR_ERR(info->id_extcon);
>  
>  			dev_info(dev, "controlling USB role\n");
>  		} else {
> -- 
> 2.20.1

-- 
heikki

Re: [PATCH] extcon: fix extcon_get_extcon_dev() error handling

[Guenter Roeck]

On 11/18/21 3:32 AM, Dan Carpenter wrote:
> The extcon_get_extcon_dev() function returns error pointers on error
> and NULL when it's a -EPROBE_DEFER defer situation.  There are eight
> callers and only two of them handled this correctly.  In the other
> callers an error pointer return would lead to a crash.
> 
> What prevents crashes is that errors can only happen in the case of
> a bug in the caller or if CONFIG_EXTCON is disabled.  Six out of
> eight callers use the Kconfig to either depend on or select
> CONFIG_EXTCON.  Thus the real life impact of these bugs is tiny.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> The two callers where the drivers can be built without CONFIG_EXTCON
> are TYPEC_FUSB302 and CHARGER_MAX8997.
> 
[ ... ]
> diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> index 7a2a17866a82..8594b59bd527 100644
> --- a/drivers/usb/typec/tcpm/fusb302.c
> +++ b/drivers/usb/typec/tcpm/fusb302.c
> @@ -1706,8 +1706,8 @@ static int fusb302_probe(struct i2c_client *client,
>   	 */
>   	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
>   		chip->extcon = extcon_get_extcon_dev(name);
> -		if (!chip->extcon)
> -			return -EPROBE_DEFER;
> +		if (IS_ERR(chip->extcon))
> +			return PTR_ERR(chip->extcon);

Why does the code not need to return -EPROBE_DEFER ? The description states
that NULL is returned in that situation. Doesn't that mean that defer situations
are no longer handled with this patch in place ?

Also, with this patch in place, the code will no longer work if extcon is disabled,
because extcon_get_extcon_dev() will return -ENODEV and the above code will bail out.
The behavior of the code wasn't optimal in that case (it would wait until timeout
in tcpm_get_current_limit() before returning), but at least it didn't fail.

Thanks,
Guenter

Re: [PATCH] extcon: fix extcon_get_extcon_dev() error handling

[Dan Carpenter]

On Thu, Nov 18, 2021 at 06:22:58AM -0800, Guenter Roeck wrote:
> On 11/18/21 3:32 AM, Dan Carpenter wrote:
> > The extcon_get_extcon_dev() function returns error pointers on error
> > and NULL when it's a -EPROBE_DEFER defer situation.  There are eight
> > callers and only two of them handled this correctly.  In the other
> > callers an error pointer return would lead to a crash.
> > 
> > What prevents crashes is that errors can only happen in the case of
> > a bug in the caller or if CONFIG_EXTCON is disabled.  Six out of
> > eight callers use the Kconfig to either depend on or select
> > CONFIG_EXTCON.  Thus the real life impact of these bugs is tiny.
> > 
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > ---
> > The two callers where the drivers can be built without CONFIG_EXTCON
> > are TYPEC_FUSB302 and CHARGER_MAX8997.
> > 
> [ ... ]
> > diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> > index 7a2a17866a82..8594b59bd527 100644
> > --- a/drivers/usb/typec/tcpm/fusb302.c
> > +++ b/drivers/usb/typec/tcpm/fusb302.c
> > @@ -1706,8 +1706,8 @@ static int fusb302_probe(struct i2c_client *client,
> >   	 */
> >   	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
> >   		chip->extcon = extcon_get_extcon_dev(name);
> > -		if (!chip->extcon)
> > -			return -EPROBE_DEFER;
> > +		if (IS_ERR(chip->extcon))
> > +			return PTR_ERR(chip->extcon);
> 
> Why does the code not need to return -EPROBE_DEFER ? The description states
> that NULL is returned in that situation. Doesn't that mean that defer situations
> are no longer handled with this patch in place ?

I'm not sure I understand what you are saying here.  In the original
code, extcon_get_extcon_dev() would return NULL and relied on the
callers to change NULL into a -EPROBE_DEFER.  If extcon_get_extcon_dev()
returned ERR_PTR(-EINVAL) (which is impossible as mentioned) the it
would lead to a crash.

In the new code, the extcon_get_extcon_dev() function returns
-EPROBE_DEFER directly so the caller code is much simpler.

> 
> Also, with this patch in place, the code will no longer work if extcon is disabled,
> because extcon_get_extcon_dev() will return -ENODEV and the above code will bail out.
> The behavior of the code wasn't optimal in that case (it would wait until timeout
> in tcpm_get_current_limit() before returning), but at least it didn't fail.

Huh.  You are right.  Initialy I thought that tcpm_get_current_limit()
would crash.  This is one of the two drivers which I mentioned that can
be built without CONFIG_EXTCON.

I will modify the version of extcon_get_extcon_dev() where CONFIG_EXTCON
is disabled to return NULL.  That is the standard/correct way to write
these.  That will turn tcpm_get_current_limit() into a no-op.

A belt and suspenders approach might be to modify the Kconfig so this
driver selects CONFIG_EXTCON.

regards,
dan carpenter

Re: [PATCH] extcon: fix extcon_get_extcon_dev() error handling

[Guenter Roeck]

On Thu, Nov 18, 2021 at 05:51:35PM +0300, Dan Carpenter wrote:
> On Thu, Nov 18, 2021 at 06:22:58AM -0800, Guenter Roeck wrote:
> > On 11/18/21 3:32 AM, Dan Carpenter wrote:
> > > The extcon_get_extcon_dev() function returns error pointers on error
> > > and NULL when it's a -EPROBE_DEFER defer situation.  There are eight
> > > callers and only two of them handled this correctly.  In the other
> > > callers an error pointer return would lead to a crash.
> > > 
> > > What prevents crashes is that errors can only happen in the case of
> > > a bug in the caller or if CONFIG_EXTCON is disabled.  Six out of
> > > eight callers use the Kconfig to either depend on or select
> > > CONFIG_EXTCON.  Thus the real life impact of these bugs is tiny.
> > > 
> > > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > > ---
> > > The two callers where the drivers can be built without CONFIG_EXTCON
> > > are TYPEC_FUSB302 and CHARGER_MAX8997.
> > > 
> > [ ... ]
> > > diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> > > index 7a2a17866a82..8594b59bd527 100644
> > > --- a/drivers/usb/typec/tcpm/fusb302.c
> > > +++ b/drivers/usb/typec/tcpm/fusb302.c
> > > @@ -1706,8 +1706,8 @@ static int fusb302_probe(struct i2c_client *client,
> > >   	 */
> > >   	if (device_property_read_string(dev, "linux,extcon-name", &name) == 0) {
> > >   		chip->extcon = extcon_get_extcon_dev(name);
> > > -		if (!chip->extcon)
> > > -			return -EPROBE_DEFER;
> > > +		if (IS_ERR(chip->extcon))
> > > +			return PTR_ERR(chip->extcon);
> > 
> > Why does the code not need to return -EPROBE_DEFER ? The description states
> > that NULL is returned in that situation. Doesn't that mean that defer situations
> > are no longer handled with this patch in place ?
> 
> I'm not sure I understand what you are saying here.  In the original
> code, extcon_get_extcon_dev() would return NULL and relied on the
> callers to change NULL into a -EPROBE_DEFER.  If extcon_get_extcon_dev()
> returned ERR_PTR(-EINVAL) (which is impossible as mentioned) the it
> would lead to a crash.
> 
> In the new code, the extcon_get_extcon_dev() function returns
> -EPROBE_DEFER directly so the caller code is much simpler.
> 
Misunderstanding on my side. I didn't get that extcon_get_extcon_dev()
now returns -EPROBE_DEFER.

> > 
> > Also, with this patch in place, the code will no longer work if extcon is disabled,
> > because extcon_get_extcon_dev() will return -ENODEV and the above code will bail out.
> > The behavior of the code wasn't optimal in that case (it would wait until timeout
> > in tcpm_get_current_limit() before returning), but at least it didn't fail.
> 
> Huh.  You are right.  Initialy I thought that tcpm_get_current_limit()
> would crash.  This is one of the two drivers which I mentioned that can
> be built without CONFIG_EXTCON.
> 
> I will modify the version of extcon_get_extcon_dev() where CONFIG_EXTCON
> is disabled to return NULL.  That is the standard/correct way to write
> these.  That will turn tcpm_get_current_limit() into a no-op.
> 
> A belt and suspenders approach might be to modify the Kconfig so this
> driver selects CONFIG_EXTCON.
> 

That would pull in unnecessary extra code, though, if the driver is supposed
to be able to work without it.

Thanks,
Guenter

> regards,
> dan carpenter
>