Hi,
On 06/18/2014 09:11 AM, Boris BREZILLON wrote:
>
> On 17/06/2014 22:44, Maxime Ripard wrote:
>> On Tue, Jun 17, 2014 at 09:38:40AM +0200, Boris BREZILLON wrote:
>>> The init_data and of_node fields of the axp2xx_matches tables are filled
>>> at each device probe by the axp20x_regulator_parse_dt function (which then
>>> calls the of_regulator_match function).
>>> This means we can probe a new device and consider data initialized during
>>> the probe of another device as valid.
>>>
>>> Reset init_data and of_node field to NULL before each probe in order to
>>> avoid this kind of issue.
>>>
>>> Signed-off-by: Boris BREZILLON <boris.brezillon@xxxxxxxxxxxxxxxxxx>
>>> ---
>>> drivers/regulator/axp20x-regulator.c | 9 +++++++++
>>> 1 file changed, 9 insertions(+)
>>>
>>> diff --git a/drivers/regulator/axp20x-regulator.c b/drivers/regulator/axp20x-regulator.c
>>> index 7a30f49..d42bf6d 100644
>>> --- a/drivers/regulator/axp20x-regulator.c
>>> +++ b/drivers/regulator/axp20x-regulator.c
>>> @@ -324,6 +324,15 @@ static int axp20x_regulator_probe(struct platform_device *pdev)
>>> nregulators = AXP20X_REG_ID_MAX;
>>> }
>>>
>>> + /*
>>> + * Reset matches table (this table might have been modified by a
>>> + * previous AXP2xx device probe).
>>> + */
>>> + for (i = 0; i < nmatches; i++) {
>>> + matches[i].init_data = NULL;
>>> + matches[i].of_node = NULL;
>>> + }
>>> +
>> That looks rather hackish, especially since we've never been in such a
>> case yet, since we have a single PMIC in our system.
>
> Even if something is unlikely to happen, it doesn't mean it's impossible.
> I'm pretty sure there are (or will be) some systems containing several
> identical PMICs in the wild, and fixing this possible bug now prevents
> us (or other developers) from having a big headache debugging this in
> the future.
If you're really worried about this, you should also be worried
about 2 probes running at the same time racing against each other
(I know the bus level code will not do that now, but what about the
future).
If you cannot treat / use the global struct as const, then you really should
have a local copy, and const-ify the global version and use it as a template
to initialize the local copy.
> BTW, what is hackish in this code ?
See above, changing a global struct, and then re-initializing it on the
next probe just is not pretty. TBH this raised my eyebrows the first time
you posted it already, but I decided to let it be. But since we're discussing
this now anyways I have to agree with Maxime.
Regards,
Hans
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