diff options
| author | Aboorva Devarajan <aboorvad@linux.ibm.com> | 2026-02-17 00:20:02 +0530 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-02-26 15:01:29 -0800 |
| commit | a0724e40a58a0e323c59707edeae5b71d15800dc (patch) | |
| tree | be2d4a8f79e670d84289bcf73e7fbafa8ef788f0 /drivers/cpuidle | |
| parent | df05c11b55c9c657afd38df5bbdf1159489b998c (diff) | |
cpuidle: Skip governor when only one idle state is available
[ Upstream commit e5c9ffc6ae1bcdb1062527d611043681ac301aca ]
On certain platforms (PowerNV systems without a power-mgt DT node),
cpuidle may register only a single idle state. In cases where that
single state is a polling state (state 0), the ladder governor may
incorrectly treat state 1 as the first usable state and pass an
out-of-bounds index. This can lead to a NULL enter callback being
invoked, ultimately resulting in a system crash.
[ 13.342636] cpuidle-powernv : Only Snooze is available
[ 13.351854] Faulting instruction address: 0x00000000
[ 13.376489] NIP [0000000000000000] 0x0
[ 13.378351] LR [c000000001e01974] cpuidle_enter_state+0x2c4/0x668
Fix this by adding a bail-out in cpuidle_select() that returns state 0
directly when state_count <= 1, bypassing the governor and keeping the
tick running.
Fixes: dc2251bf98c6 ("cpuidle: Eliminate the CPUIDLE_DRIVER_STATE_START symbol")
Signed-off-by: Aboorva Devarajan <aboorvad@linux.ibm.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/20260216185005.1131593-2-aboorvad@linux.ibm.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/cpuidle')
| -rw-r--r-- | drivers/cpuidle/cpuidle.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index c7876e9e024f..65fbb8e807b9 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -359,6 +359,16 @@ noinstr int cpuidle_enter_state(struct cpuidle_device *dev, int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, bool *stop_tick) { + /* + * If there is only a single idle state (or none), there is nothing + * meaningful for the governor to choose. Skip the governor and + * always use state 0 with the tick running. + */ + if (drv->state_count <= 1) { + *stop_tick = false; + return 0; + } + return cpuidle_curr_governor->select(drv, dev, stop_tick); } |