Race condition in TPA6130A2 (Was: Re: Nokia N900 - audio TPA6130A2 problems)

Pali Rohár
2016-04-01T10:43:40Z

On Wednesday 16 March 2016 15:47:10 Sebastian Reichel wrote:
> I just had another look at the driver and I think there is a race
> condition for tpa6130a2_add_controls() and tpa6130a2_stereo_enable().
>
> As far as I can see both functions check for "tpa6130a2_client !=
> NULL". tpa6130a2_client is set before the probe function has finished,
> though. Simplified probe:
>
> ...
> tpa6130a2_client = client;
> set_default_regs();
> acquire_power_gpio();
> acquire_regulator();
> tpa6130a2_power(1); // needs tpa6130a2_client
> check_device();
> tpa6130a2_power(0); // needs tpa6130a2_client
> ...
>
> If tpa6130a2_add_controls() or tpa6130a2_stereo_enable() is called
> after tpa6130a2 probe has started, but before probe has completed,
> tpa6130a2_client is set, but not yet initialized. The race condition
> can be fixed easily by moving the tpa6130a2_client assignment directly
> after the regulator acquisition.
>
> -- Sebastian

Is this race condition really relevant? If yes, then it should be fixed.

--
Pali Rohár
pali.rohar@gmail.com