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Thu, 16 Dec 2021 06:16:45 +0000 (GMT) Received: from epsmgms1p2.samsung.com (unknown [182.195.42.42]) by epsmtrp2.samsung.com (KnoxPortal) with ESMTP id 20211216061645epsmtrp22bc23d79c6074a7a1666ea7854d8d12f~BJ7bpqVSz0074200742epsmtrp2S; Thu, 16 Dec 2021 06:16:45 +0000 (GMT) X-AuditID: b6c32a35-9adff7000000fa55-6d-61bad9d55a3a Received: from epsmtip2.samsung.com ( [182.195.34.31]) by epsmgms1p2.samsung.com (Symantec Messaging Gateway) with SMTP id D9.FB.08738.DC9DAB16; Thu, 16 Dec 2021 15:16:45 +0900 (KST) Received: from [10.113.221.102] (unknown [10.113.221.102]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20211216061645epsmtip2a861342427123840bb771f000920afbe~BJ7bae5Gp1591415914epsmtip2L; Thu, 16 Dec 2021 06:16:45 +0000 (GMT) From: Chanwoo Choi Subject: Re: [PATCH v2] extcon: fix extcon_get_extcon_dev() error handling To: Dan Carpenter , MyungJoo Ham , Guenter Roeck Cc: Sebastian Reichel , Chen-Yu Tsai , Hans de Goede , Felipe Balbi , Greg Kroah-Hartman , Heikki Krogerus , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-usb@vger.kernel.org, linux-omap@vger.kernel.org, kernel-janitors@vger.kernel.org Organization: Samsung Electronics Message-ID: <562b12ff-e395-c818-787e-7fd6ee6d53fb@samsung.com> Date: Thu, 16 Dec 2021 15:39:46 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:59.0) Gecko/20100101 Thunderbird/59.0 MIME-Version: 1.0 In-Reply-To: <20211123083925.GA3277@kili> Content-Language: en-US Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrHJsWRmVeSWpSXmKPExsWy7bCmru7Vm7sSDaZckrY41vaE3eL1v+ks Fs2L17NZvDk+ncmia/VOFoutt6QtLu+aw2Yxe0k/i8Xn3iOMFouWtTJbPFl4hsniduMKNovT u0ssfh46z+TA57Hh0WpWj02rOtk85p0M9Ng/dw27x8ent1g83u+7yuax83sDu0ffllWMHp83 yQVwRmXbZKQmpqQWKaTmJeenZOal2yp5B8c7x5uaGRjqGlpamCsp5CXmptoqufgE6Lpl5gCd rqRQlphTChQKSCwuVtK3synKLy1JVcjILy6xVUotSMkpMC3QK07MLS7NS9fLSy2xMjQwMDIF KkzIzlh2cT9TwTyfihsz17A3MO6062Lk5JAQMJG49+kLWxcjF4eQwA5GidPTW6GcT4wS2xu2 s4JUCQl8ZpRomZAM0zF99QVWiKJdQPGdn5khnPeMEhd+32IBqWIT0JLY/+IGG4gtLOAl0TX7 EJgtIlAt0T51LVg3s0AHs8T/fevAVvALKEpc/fGYEcTmFbCTuDbnHTOIzSKgKnHx7BuwoaIC YRInt7VA1QhKnJz5BCzOKaAp8b95MVicWUBc4taT+UwQtrzE9rdzwK6TEHjDIbH1YB8bxA8u Ev2TO5ghbGGJV8e3sEPYUhKf3+1lg2hYxijxa3InE4SznlHi5axOqA5jif1LJwMlOIBWaEqs 36UPEVaU2Pl7LtQVfBLvvvawgpRICPBKdLQJQZQoS1x+cJcJwpaUWNzeyTaBUWkWkn9mIflh FpIfZiEsW8DIsopRLLWgODc9tdiwwBAe38n5uZsYwQlby3QH48S3H/QOMTJxMB5ilOBgVhLh fRKxK1GINyWxsiq1KD++qDQntfgQoykwhCcyS4km5wNzRl5JvKGJpYGJmZGxiYWhmaGSOO8L /+mJQgLpiSWp2ampBalFMH1MHJxSDUz9QTmJCz5HxbLN+OOS9PmZpZLKjBytjRcY3wlk/r85 73XNUjnphn99uSVTM/9rG+9+96dKhjf14cXTvbxPpoWG5xzwivl+lPXx1N7obd9mOrGfyXXt uzfzVihX0rebcz8uNBZRXs0ne+GlsO0NueWBxspn7nplVp1T6DmrkrrI6k9TWEMRw5pcr1sH /Zj+dixyPBq4vPxByPuzs7MqV0y+3P77dnTbu/9hvrWH6vews3Ls/Zf+Rfdu99PQxS+uHJbm OuqQIS+R8OCffFSo4v/Xj3MmLJ2yUWiD5WMZll6VK4zz3vP66q8RmHVT5d+5uTYbqvhOPJGW 8F/i8OlB+0/zMlF+8bMpzYZPrac6RnYosRRnJBpqMRcVJwIAVQmD7WEEAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrOIsWRmVeSWpSXmKPExsWy7bCSvO7Zm7sSDXafN7Q41vaE3eL1v+ks Fs2L17NZvDk+ncmia/VOFoutt6QtLu+aw2Yxe0k/i8Xn3iOMFouWtTJbPFl4hsniduMKNovT u0ssfh46z+TA57Hh0WpWj02rOtk85p0M9Ng/dw27x8ent1g83u+7yuax83sDu0ffllWMHp83 yQVwRnHZpKTmZJalFunbJXBlLLu4n6lgnk/FjZlr2BsYd9p1MXJySAiYSExffYG1i5GLQ0hg B6PEtBl32SESkhLTLh5l7mLkALKFJQ4fLoaoecsoMevvKhaQGjYBLYn9L26wgdjCAl4SXbMP gdkiAtUSy1bNZAJpYBboYpbY9OI+2FAhgRqJmScWMYHY/AKKEld/PGYEsXkF7CSuzXnHDGKz CKhKXDz7BmyBqECYxM4lj5kgagQlTs58AhbnFNCU+N+8GKyXWUBd4s+8S8wQtrjErSfzmSBs eYntb+cwT2AUnoWkfRaSlllIWmYhaVnAyLKKUTK1oDg3PbfYsMAoL7Vcrzgxt7g0L10vOT93 EyM4brW0djDuWfVB7xAjEwfjIUYJDmYlEd4nEbsShXhTEiurUovy44tKc1KLDzFKc7AoifNe 6DoZLySQnliSmp2aWpBaBJNl4uCUamBKl1s44ZGopcqi04m1Bx9V8V39dUFjzaTep9OFM7fL mGncTV+cGHxhoccq7YbdxsIcjyYdnNx86pBKjvOfbzHue+Yr1h5JfVNd4/tG9FZj6IRfBrce u01ed+KDxE0BLeGDE1WWbZ34Nm1Jb4+UeGj3k+nMr6oPrAlfveoMu6NKJleqbVrJjMe7Ff+1 T7NMXh56NMb1/4e429ttjDf9tWsWsmaddcK1e21Gjbzos70n/S8fvXdf/Zpk5rvfsqWbl9rN jdbdn13ZwjhHNXj1npL2jwzP6/hn8M3QuZi5/nUFW6XducQH56ZNebTE19bdfomGc/y/ZZqF B7wcDq1T4ZxttfEth6pp3Mx3XJ8Kqz88VWIpzkg01GIuKk4EAEsuT1lKAwAA X-CMS-MailID: 20211216061645epcas1p31af8f90a37617fcda7ea6dd0ced0a37e X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: SVC_REQ_APPROVE CMS-TYPE: 101P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20211123084357epcas1p14833147710153f9606f14941ac8b0d96 References: <20211123083925.GA3277@kili> Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Hi Dan, First of all, sorry for late reply. There is one issue. About this issue, I already discussed on patch[1] [1] https://lore.kernel.org/lkml/5BEB63C3.1020504@samsung.com/ extcon_get_extcon_dev() is used for anywhere except for probe step. But EPROBE_DEFER is only used on probe step. So that it is not clear to return EPROBE_DEFER from extcon_get_extcon_dev() because extcon_get_extcon_dev() never know either call it on probe function or not. On 11/23/21 5:43 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 > --- > v2: return NULL when CONFIG_EXTCON is disabled > > 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-axp288.c | 4 ++-- > 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 ++-- > include/linux/extcon.h | 2 +- > 9 files changed, 27 insertions(+), 32 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/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