From: Ido Schimmel idosch@nvidia.com
[ Upstream commit 6d206b1ea9f48433a96edec7028586db1d947911 ]
The cooling levels array is supposed to prevent the system fans from being configured below a 20% duty cycle as otherwise some of them get stuck at 0 RPM.
Due to an off-by-one error, the last element in the array was not initialized, causing it to be set to zero, which in turn lead to fans being configured with a 0% duty cycle in maximum cooling state.
Since commit 332fdf951df8 ("mlxsw: thermal: Fix out-of-bounds memory accesses") the contents of the array are static. Therefore, instead of fixing the initialization of the array, simply remove it and adjust thermal_cooling_device_ops::set_cur_state() so that the configured duty cycle is never set below 20%.
Before:
# cat /sys/class/thermal/thermal_zone0/cdev0/type mlxsw_fan # echo 10 > /sys/class/thermal/thermal_zone0/cdev0/cur_state # cat /sys/class/hwmon/hwmon0/name mlxsw # cat /sys/class/hwmon/hwmon0/pwm1 0
After:
# cat /sys/class/thermal/thermal_zone0/cdev0/type mlxsw_fan # echo 10 > /sys/class/thermal/thermal_zone0/cdev0/cur_state # cat /sys/class/hwmon/hwmon0/name mlxsw # cat /sys/class/hwmon/hwmon0/pwm1 255
This bug was uncovered when the thermal subsystem repeatedly tried to configure the cooling devices to their maximum state due to another issue [1]. This resulted in the fans being stuck at 0 RPM, which eventually lead to the system undergoing thermal shutdown.
[1] https://lore.kernel.org/netdev/ZA3CFNhU4AbtsP4G@shredder/
Fixes: a421ce088ac8 ("mlxsw: core: Extend cooling device with cooling levels") Signed-off-by: Ido Schimmel idosch@nvidia.com Reviewed-by: Vadim Pasternak vadimp@nvidia.com Signed-off-by: Petr Machata petrm@nvidia.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/mellanox/mlxsw/core_thermal.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c b/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c index c5240d38c9dbd..09ed6e5fa6c34 100644 --- a/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c +++ b/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c @@ -105,7 +105,6 @@ struct mlxsw_thermal { struct thermal_zone_device *tzdev; int polling_delay; struct thermal_cooling_device *cdevs[MLXSW_MFCR_PWMS_MAX]; - u8 cooling_levels[MLXSW_THERMAL_MAX_STATE + 1]; struct thermal_trip trips[MLXSW_THERMAL_NUM_TRIPS]; struct mlxsw_cooling_states cooling_states[MLXSW_THERMAL_NUM_TRIPS]; struct mlxsw_thermal_area line_cards[]; @@ -468,7 +467,7 @@ static int mlxsw_thermal_set_cur_state(struct thermal_cooling_device *cdev, return idx;
/* Normalize the state to the valid speed range. */ - state = thermal->cooling_levels[state]; + state = max_t(unsigned long, MLXSW_THERMAL_MIN_STATE, state); mlxsw_reg_mfsc_pack(mfsc_pl, idx, mlxsw_state_to_duty(state)); err = mlxsw_reg_write(thermal->core, MLXSW_REG(mfsc), mfsc_pl); if (err) { @@ -859,10 +858,6 @@ int mlxsw_thermal_init(struct mlxsw_core *core, } }
- /* Initialize cooling levels per PWM state. */ - for (i = 0; i < MLXSW_THERMAL_MAX_STATE; i++) - thermal->cooling_levels[i] = max(MLXSW_THERMAL_MIN_STATE, i); - thermal->polling_delay = bus_info->low_frequency ? MLXSW_THERMAL_SLOW_POLL_INT : MLXSW_THERMAL_POLL_INT;