[PATCH v2 1/2] extcon: fix hang and extcon_get/set_cable_state().

From: Roger Quadros
Date: Tue Jul 07 2015 - 09:06:36 EST


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@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Roger Quadros <rogerq@xxxxxx>
---
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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