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Message-ID: <978e3529-512a-3fc6-3a9f-5f34d5fd6ce7@samsung.com>
Date: Thu, 3 Feb 2022 14:24:44 +0900
From: Chanwoo Choi <cw00.choi@...sung.com>
To: Felipe Balbi <balbi@...nel.org>
Cc: Dan Carpenter <dan.carpenter@...cle.com>,
MyungJoo Ham <myungjoo.ham@...sung.com>,
Guenter Roeck <linux@...ck-us.net>,
Sebastian Reichel <sre@...nel.org>,
Chen-Yu Tsai <wens@...e.org>,
Hans de Goede <hdegoede@...hat.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
linux-usb@...r.kernel.org, linux-omap@...r.kernel.org,
kernel-janitors@...r.kernel.org
Subject: Re: [PATCH v3] extcon: fix extcon_get_extcon_dev() error handling
Hi Felipe,
Gently Ping.
Best Regards,
Chanwoo Choi
On 12/20/21 10:20 AM, Chanwoo Choi wrote:
> Hi Sebastian and Felipe,
>
> If Sebastian and Felipe don't have any additional opinion,
> could you please reply the review for this patch?
>
> And if Sebastian and Felipe agree, I'll merge it to extcon tree.
>
>
> Best Regards,
> Chanwoo Choi
>
>
> On 12/17/21 3:28 PM, Dan Carpenter wrote:
>> The extcon_get_extcon_dev() function returns error pointers on error,
>> NULL when it's a -EPROBE_DEFER defer situation, and ERR_PTR(-ENODEV)
>> when the CONFIG_EXTCON option is disabled. This is very complicated for
>> the callers to handle and a number of them had bugs that would lead to
>> an Oops.
>>
>> In real life, there are two things which prevented crashes. First,
>> error pointers would only be returned if there was bug in the caller
>> where they passed a NULL "extcon_name" and none of them do that.
>> Second, only two out of the eight drivers will build when CONFIG_EXTCON
>> is disabled.
>>
>> The normal way to write this would be to return -EPROBE_DEFER directly
>> when appropriate and return NULL when CONFIG_EXTCON is disabled. Then
>> the error handling is simple and just looks like:
>>
>> dev->edev = extcon_get_extcon_dev(acpi_dev_name(adev));
>> if (IS_ERR(dev->edev))
>> return PTR_ERR(dev->edev);
>>
>> For the two drivers which can build with CONFIG_EXTCON disabled, then
>> extcon_get_extcon_dev() will now return NULL which is not treated as an
>> error and the probe will continue successfully. Those two drivers are
>> "typec_fusb302" and "max8997-battery". In the original code, the
>> typec_fusb302 driver had an 800ms hang in tcpm_get_current_limit() but
>> now that function is a no-op. For the max8997-battery driver everything
>> should continue working as is.
>>
>> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
>> ---
>> v2: return NULL when CONFIG_EXTCON is disabled
>> v3: Add a note to extcon_get_extcon_dev() to say that it may only be
>> called from probe().
>>
>> drivers/extcon/extcon.c | 4 +++-
>> include/linux/extcon.h | 2 +-
>> drivers/extcon/extcon-axp288.c | 4 ++--
>> 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 ++--
>> 9 files changed, 29 insertions(+), 32 deletions(-)
>>
>> diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
>> index e7a9561a826d..9eb92997f3ae 100644
>> --- a/drivers/extcon/extcon.c
>> +++ b/drivers/extcon/extcon.c
>> @@ -863,6 +863,8 @@ EXPORT_SYMBOL_GPL(extcon_set_property_capability);
>> * @extcon_name: the extcon name provided with extcon_dev_register()
>> *
>> * Return the pointer of extcon device if success or ERR_PTR(err) if fail.
>> + * NOTE: This function returns -EPROBE_DEFER so it may only be called from
>> + * probe() functions.
>> */
>> struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name)
>> {
>> @@ -876,7 +878,7 @@ 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/include/linux/extcon.h b/include/linux/extcon.h
>> index 0c19010da77f..685401d94d39 100644
>> --- a/include/linux/extcon.h
>> +++ b/include/linux/extcon.h
>> @@ -296,7 +296,7 @@ static inline void devm_extcon_unregister_notifier_all(struct device *dev,
>>
>> static inline struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name)
>> {
>> - return ERR_PTR(-ENODEV);
>> + return NULL;
>> }
>>
>> static inline struct extcon_dev *extcon_find_edev_by_node(struct device_node *node)
>> 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 {
>> 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 72f9001b0792..96c55eaf3f80 100644
>> --- a/drivers/usb/typec/tcpm/fusb302.c
>> +++ b/drivers/usb/typec/tcpm/fusb302.c
>> @@ -1708,8 +1708,8 @@ 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");
>>
>
>
>
>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
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