On 02/03/2023 10:47, Thierry Reding wrote:
On Wed, Mar 01, 2023 at 09:14:44PM +0100, Daniel Lezcano wrote:The function tegra_tsensor_enable_hw_channel() takes the thermal zone lock to prevent "a potential" race with a call to set_trips() callback. The driver must not play with the thermal framework core code internals. The tegra_tsensor_enable_hw_channel() is called by: - the suspend / resume callbacks - the probe function after the thermal zones are registered The thermal zone lock taken in this function is supposed to protect from a call to the set_trips() callback which writes in the same register. The potential race is when suspend / resume are called at the same time as set_trips. This one is called only in thermal_zone_device_update(). - At suspend time, the 'in_suspend' is set, thus the thermal_zone_device_update() bails out immediately and set_trips is not called during this moment. - At resume time, the thermal zone is updated at PM_POST_SUSPEND, thus the driver has already set the TH2 temperature. - At probe time, we register the thermal zone and then we set the TH2. The only scenario I can see so far is the interrupt fires, the thermal_zone_update() is called exactly at the moment tegra_tsensor_enable_hw_channel() a few lines after registering it. Enable the channels before setting up the interrupt. We close the potential race window without using the thermal zone's lock. Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> Suggested-by: Thierry Reding <thierry.reding@xxxxxxxxx> --- drivers/thermal/tegra/tegra30-tsensor.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-)Acked-by: Thierry Reding <treding@xxxxxxxxxx>
Thanks for your review May I ask you to have a look at patch 2 and 8 ? Thanks -- Daniel -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog
