[RFC PATCH 1/3] eeprom: Add a simple EEPROM framework

Srinivas Kandagatla
2015-02-23T15:38:28Z

Thankyou for the comments.

On 23/02/15 15:04, Mark Brown wrote:
> On Thu, Feb 19, 2015 at 05:08:28PM +0000, Srinivas Kandagatla wrote:
>
>> .../devicetree/bindings/eeprom/eeprom.txt | 48 ++++
>> drivers/Kconfig | 2 +
>> drivers/Makefile | 1 +
>> drivers/eeprom/Kconfig | 19 ++
>> drivers/eeprom/Makefile | 9 +
>> drivers/eeprom/core.c | 290 +++++++++++++++++++++
>> include/linux/eeprom-consumer.h | 73 ++++++
>> include/linux/eeprom-provider.h | 51 ++++
>
> This seems to have a bunch of different things in it - there's some
> binding, there's some framework code, there's some user code for the
> framework... splitting it up more would probably help with review.
> I'd at least make sure the framework is split from the DT code, that
> will cut down on the bulk and help make sure the framework isn't too DT
> tied.

Yes I agree, will make sure that I split it into different patches in
next version.
>
>> + if (read)
>> + rc = regmap_bulk_read(eeprom->regmap, offset,
>> + buf, count/eeprom->stride);
>> + else
>> + rc = regmap_bulk_write(eeprom->regmap, offset,
>> + buf, count/eeprom->stride);
>> +
>> + if (IS_ERR_VALUE(rc))
>> + return 0;
>> +
>> + return count;
>> +}
>
>> +static ssize_t bin_attr_eeprom_read(struct file *filp, struct kobject *kobj,
>> + struct bin_attribute *attr,
>> + char *buf, loff_t offset, size_t count)
>> +{
>> + return bin_attr_eeprom_read_write(kobj, buf, offset, count, true);
>> +}
>
> I'm not sure the factoring out is actually helping the clarity here TBH.
>
ok.

>> +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;
>> +}
>> +EXPORT_SYMBOL(eeprom_unregister);
>
> Here we return having dropped the lock without doing anything else with
> the eeprom, meaning the caller could delete it.
>
>> + mutex_lock(&eeprom_list_mutex);
>> +
>> + list_for_each_entry(e, &eeprom_list, list) {
>> + if (args.np == e->edev.of_node) {
>> + eeprom = e;
>> + break;
>> + }
>> + }
>> + mutex_unlock(&eeprom_list_mutex);
>
> Here we iterate the list, find the relevant eeprom and drop the lock
> while still holding a reference to the eeprom we just found. This means
> that a removal could race with us and free the eeprom underneath us.
> I'm also not seeing anything stopping or even noticing a device being
> removed with a cell active on it.
>
As suggested by Stephen Boyd reference counting on eeprom should ensure
safe removal of eeprom.

>> +/**
>> + * eeprom_cell_get(): Get eeprom cell of device form a given index.
>> + *
>> + * @dev: Device that will be interacted with
>> + * @index: Index of the eeprom cell.
>> + *
>> + * The return value will be an ERR_PTR() on error or a valid pointer
>> + * to a struct eeprom_cell. The eeprom_cell will be freed by the
>> + * eeprom_cell_put().
>> + */
>> +struct eeprom_cell *eeprom_cell_get(struct device *dev, int index);
>
> Normally the kerneldoc goes with the function definition, not the
> prototype.
Thats true, will fix it in next version.
>