Messages in this thread |  | | Subject | Re: [PATCH v2] extcon: fix extcon_get_extcon_dev() error handling | From | Guenter Roeck <> | Date | Tue, 23 Nov 2021 06:48:41 -0800 |
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On 11/23/21 12:43 AM, 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@oracle.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
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