lkml.org 
[lkml]   [2021]   [Nov]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v2] extcon: fix extcon_get_extcon_dev() error handling
From
Date
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>

\
 
 \ /
  Last update: 2021-11-23 15:49    [W:0.090 / U:3.540 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site