This is a note to let you know that I've just added the patch titled
mlxsw: core_thermal: Fix fan speed in maximum cooling state
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mlxsw-core_thermal-fix-fan-speed-in-maximum-cooling-.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit bdb027a7b89c2f6bfcc23bef62276c7d39bf370f
Author: Ido Schimmel <idosch@xxxxxxxxxx>
Date: Fri Mar 17 16:32:59 2023 +0100
mlxsw: core_thermal: Fix fan speed in maximum cooling state
[ 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@xxxxxxxxxx>
Reviewed-by: Vadim Pasternak <vadimp@xxxxxxxxxx>
Signed-off-by: Petr Machata <petrm@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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;
