Re: [PATCH] extcon: fix extcon_get_extcon_dev() error handling
From: Guenter Roeck <linux@roeck-us.net>
Date: 2021-11-18 14:23:07
Also in:
kernel-janitors, linux-omap, linux-pm, lkml
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 <redacted> --- The two callers where the drivers can be built without CONFIG_EXTCON are TYPEC_FUSB302 and CHARGER_MAX8997.
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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