linux-kernel - Re: [PATCH v2 1/2] extcon: fix hang and extcon_get/set_cable

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Date:	Fri, 10 Jul 2015 17:54:47 +0200
From:	Chanwoo Choi <cwchoi00@...il.com>
To:	Roger Quadros <rogerq@...com>
Cc:	ivan.ivanov@...aro.org, linux-omap@...r.kernel.org,
	linux-usb@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v2 1/2] extcon: fix hang and extcon_get/set_cable_state().

Hi Roger,

Thanks for your working.

I'll review, test and apply it on next week because I'm on vacation now.

Thanks,
Chanwoo Choi

On Tue, Jul 7, 2015 at 3:06 PM, Roger Quadros <rogerq@...com> wrote:
> Users of find_cable_index_by_name() will cause a kernel hang
> as the while loop counter is never incremented and end condition
> is never reached.
>
> extcon_get_cable_state() and extcon_set_cable_state() are broken
> because they use cable index instead of cable id. This causes
> the first cable state (cable.0) to be always invalid in sysfs
> or extcon_get_cable_state() users.
>
> Introduce a new function find_cable_id_by_name() that fixes
> both of the above issues.
>
> Fixes: commit 73b6ecdb93e8 ("extcon: Redefine the unique id of supported external connectors without 'enum extcon' type")
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
>  drivers/extcon/extcon.c | 38 +++++++++++++++++++++++++++++---------
>  1 file changed, 29 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
> index 76157ab..987dd3c 100644
> --- a/drivers/extcon/extcon.c
> +++ b/drivers/extcon/extcon.c
> @@ -124,22 +124,34 @@ static int find_cable_index_by_id(struct extcon_dev *edev, const unsigned int id
>         return -EINVAL;
>  }
>
> -static int find_cable_index_by_name(struct extcon_dev *edev, const char *name)
> +static int find_cable_id_by_name(struct extcon_dev *edev, const char *name)
>  {
> -       unsigned int id = EXTCON_NONE;
> +       unsigned int id = -EINVAL;
>         int i = 0;
>
> -       if (edev->max_supported == 0)
> -               return -EINVAL;
> -
> -       /* Find the the number of extcon cable */
> +       /* Find the id of extcon cable */
>         while (extcon_name[i]) {
>                 if (!strncmp(extcon_name[i], name, CABLE_NAME_MAX)) {
>                         id = i;
>                         break;
>                 }
> +
> +               i++;
>         }
>
> +       return id;
> +};
> +
> +static int find_cable_index_by_name(struct extcon_dev *edev, const char *name)
> +{
> +       unsigned int id = EXTCON_NONE;
> +
> +       if (edev->max_supported == 0)
> +               return -EINVAL;
> +
> +       /* Find the the number of extcon cable */
> +       id = find_cable_id_by_name(edev, name);
> +
>         if (id == EXTCON_NONE)
>                 return -EINVAL;
>
> @@ -228,9 +240,11 @@ static ssize_t cable_state_show(struct device *dev,
>         struct extcon_cable *cable = container_of(attr, struct extcon_cable,
>                                                   attr_state);
>
> +       int i = cable->cable_index;
> +
>         return sprintf(buf, "%d\n",
>                        extcon_get_cable_state_(cable->edev,
> -                                              cable->cable_index));
> +                                              cable->edev->supported_cable[i]));
>  }
>
>  /**
> @@ -341,6 +355,9 @@ int extcon_get_cable_state_(struct extcon_dev *edev, const unsigned int id)
>  {
>         int index;
>
> +       if (id == EXTCON_NONE)
> +               return -EINVAL;
> +
>         index = find_cable_index_by_id(edev, id);
>         if (index < 0)
>                 return index;
> @@ -361,7 +378,7 @@ EXPORT_SYMBOL_GPL(extcon_get_cable_state_);
>   */
>  int extcon_get_cable_state(struct extcon_dev *edev, const char *cable_name)
>  {
> -       return extcon_get_cable_state_(edev, find_cable_index_by_name
> +       return extcon_get_cable_state_(edev, find_cable_id_by_name
>                                                 (edev, cable_name));
>  }
>  EXPORT_SYMBOL_GPL(extcon_get_cable_state);
> @@ -380,6 +397,9 @@ int extcon_set_cable_state_(struct extcon_dev *edev, unsigned int id,
>         u32 state;
>         int index;
>
> +       if (id == EXTCON_NONE)
> +               return -EINVAL;
> +
>         index = find_cable_index_by_id(edev, id);
>         if (index < 0)
>                 return index;
> @@ -404,7 +424,7 @@ EXPORT_SYMBOL_GPL(extcon_set_cable_state_);
>  int extcon_set_cable_state(struct extcon_dev *edev,
>                         const char *cable_name, bool cable_state)
>  {
> -       return extcon_set_cable_state_(edev, find_cable_index_by_name
> +       return extcon_set_cable_state_(edev, find_cable_id_by_name
>                                         (edev, cable_name), cable_state);
>  }
>  EXPORT_SYMBOL_GPL(extcon_set_cable_state);
> --
> 2.1.4
>
> --
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