On 20/02/15 17:46, Russell King - ARM Linux wrote:
On Thu, Feb 19, 2015 at 05:08:28PM +0000, Srinivas Kandagatla wrote:
+static struct class eeprom_class = {
+ .name = "eeprom",
+ .dev_groups = eeprom_dev_groups,
+};
+
+int eeprom_register(struct eeprom_device *eeprom)
+{
+ int rval;
+
+ if (!eeprom->regmap || !eeprom->size) {
+ dev_err(eeprom->dev, "Regmap not found\n");
+ return -EINVAL;
+ }
+
+ eeprom->id = ida_simple_get(&eeprom_ida, 0, 0, GFP_KERNEL);
+ if (eeprom->id < 0)
+ return eeprom->id;
+
+ eeprom->edev.class = &eeprom_class;
+ eeprom->edev.parent = eeprom->dev;
+ eeprom->edev.of_node = eeprom->dev ? eeprom->dev->of_node : NULL;
+ dev_set_name(&eeprom->edev, "eeprom%d", eeprom->id);
+
+ device_initialize(&eeprom->edev);
+
+ dev_dbg(&eeprom->edev, "Registering eeprom device %s\n",
+ dev_name(&eeprom->edev));
+
+ rval = device_add(&eeprom->edev);
+ if (rval)
+ return rval;
+
+ mutex_lock(&eeprom_list_mutex);
+ list_add(&eeprom->list, &eeprom_list);
+ mutex_unlock(&eeprom_list_mutex);
+
+ return 0;
+}
+EXPORT_SYMBOL(eeprom_register);
+
+int eeprom_unregister(struct eeprom_device *eeprom)
+{
+ device_del(&eeprom->edev);
+
+ mutex_lock(&eeprom_list_mutex);
+ list_del(&eeprom->list);
+ mutex_unlock(&eeprom_list_mutex);
+
+ return 0;
There's problems with this. "edev" is embedded into eeprom, and "edev"
is a refcounted structure - it has a lifetime, and the lifetime of
eeprom is thus determined by edev.
What this means is that calling eeprom_unregister() and then freeing
the eeprom structure is a potentially unsafe operation - the memory
backing edev must only be freed when the release method for the
struct device has been called.
Thats a good catch, Yes I see the issue.
Moving the struct eeprom_device allocation to eeprom core.c should
address this issue. This makes eeprom self contained and can safely free
the eeprom_device memory in eeprom_class.eeprom_release().
Will fix this in next version.
+struct eeprom_device {
+ struct regmap *regmap;
+ int stride;
+ size_t size;
+ struct device *dev;
Failing to understand and address the driver model life time issues is
a major blocker for this patch. Sorry.
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