kernel/linux.git/drivers/cpuidle, branch v6.1.168

sched: idle: Make skipping governor callbacks more consistent

2026-03-25T10:03:05+00:00

[ Upstream commit d557640e4ce589a24dca5ca7ce3b9680f471325f ] If the cpuidle governor .select() callback is skipped because there is only one idle state in the cpuidle driver, the .reflect() callback should be skipped as well, at least for consistency (if not for correctness), so do it. Fixes: e5c9ffc6ae1b ("cpuidle: Skip governor when only one idle state is available") Signed-off-by: Rafael J. Wysocki Reviewed-by: Christian Loehle Reviewed-by: Aboorva Devarajan Reviewed-by: Frederic Weisbecker Link: https://patch.msgid.link/12857700.O9o76ZdvQC@rafael.j.wysocki Signed-off-by: Sasha Levin

cpuidle: Skip governor when only one idle state is available

2026-03-04T12:20:03+00:00

[ 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 Reviewed-by: Christian Loehle Link: https://patch.msgid.link/20260216185005.1131593-2-aboorvad@linux.ibm.com Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

cpuidle: Fail cpuidle device registration if there is one already

2025-12-06T21:12:16+00:00

[ Upstream commit 7b1b7961170e4fcad488755e5ffaaaf9bd527e8f ] Refuse to register a cpuidle device if the given CPU has a cpuidle device already and print a message regarding it. Without this, an attempt to register a new cpuidle device without unregistering the existing one leads to the removal of the existing cpuidle device without removing its sysfs interface. Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

Revert "cpuidle: menu: Avoid discarding useful information"

2025-10-29T13:04:37+00:00

commit 10fad4012234a7dea621ae17c0c9486824f645a0 upstream. It is reported that commit 85975daeaa4d ("cpuidle: menu: Avoid discarding useful information") led to a performance regression on Intel Jasper Lake systems because it reduced the time spent by CPUs in idle state C7 which is correlated to the maximum frequency the CPUs can get to because of an average running power limit [1]. Before that commit, get_typical_interval() would have returned UINT_MAX whenever it had been unable to make a high-confidence prediction which had led to selecting the deepest available idle state too often and both power and performance had been inadequate as a result of that on some systems. However, this had not been a problem on systems with relatively aggressive average running power limits, like the Jasper Lake systems in question, because on those systems it was compensated by the ability to run CPUs faster. It was addressed by causing get_typical_interval() to return a number based on the recent idle duration information available to it even if it could not make a high-confidence prediction, but that clearly did not take the possible correlation between idle power and available CPU capacity into account. For this reason, revert most of the changes made by commit 85975daeaa4d, except for one cosmetic cleanup, and add a comment explaining the rationale for returning UINT_MAX from get_typical_interval() when it is unable to make a high-confidence prediction. Fixes: 85975daeaa4d ("cpuidle: menu: Avoid discarding useful information") Closes: https://lore.kernel.org/linux-pm/36iykr223vmcfsoysexug6s274nq2oimcu55ybn6ww4il3g3cv@cohflgdbpnq7/ [1] Reported-by: Sergey Senozhatsky Cc: All applicable Signed-off-by: Rafael J. Wysocki Link: https://patch.msgid.link/3663603.iIbC2pHGDl@rafael.j.wysocki Signed-off-by: Greg Kroah-Hartman

cpuidle: governors: menu: Avoid using invalid recent intervals data

2025-10-19T14:23:11+00:00

commit fa3fa55de0d6177fdcaf6fc254f13cc8f33c3eed upstream. Marc has reported that commit 85975daeaa4d ("cpuidle: menu: Avoid discarding useful information") caused the number of wakeup interrupts to increase on an idle system [1], which was not expected to happen after merely allowing shallower idle states to be selected by the governor in some cases. However, on the system in question, all of the idle states deeper than WFI are rejected by the driver due to a firmware issue [2]. This causes the governor to only consider the recent interval duriation data corresponding to attempts to enter WFI that are successful and the recent invervals table is filled with values lower than the scheduler tick period. Consequently, the governor predicts an idle duration below the scheduler tick period length and avoids stopping the tick more often which leads to the observed symptom. Address it by modifying the governor to update the recent intervals table also when entering the previously selected idle state fails, so it knows that the short idle intervals might have been the minority had the selected idle states been actually entered every time. Fixes: 85975daeaa4d ("cpuidle: menu: Avoid discarding useful information") Link: https://lore.kernel.org/linux-pm/86o6sv6n94.wl-maz@kernel.org/ [1] Link: https://lore.kernel.org/linux-pm/7ffcb716-9a1b-48c2-aaa4-469d0df7c792@arm.com/ [2] Signed-off-by: Rafael J. Wysocki Tested-by: Christian Loehle Tested-by: Marc Zyngier Reviewed-by: Christian Loehle Link: https://patch.msgid.link/2793874.mvXUDI8C0e@rafael.j.wysocki Cc: Sergey Senozhatsky Signed-off-by: Greg Kroah-Hartman

cpuidle: qcom-spm: fix device and OF node leaks at probe

2025-10-15T09:56:28+00:00

[ Upstream commit cdc06f912670c8c199d5fa9e78b64b7ed8e871d0 ] Make sure to drop the reference to the saw device taken by of_find_device_by_node() after retrieving its driver data during probe(). Also drop the reference to the CPU node sooner to avoid leaking it in case there is no saw node or device. Fixes: 60f3692b5f0b ("cpuidle: qcom_spm: Detach state machine from main SPM handling") Signed-off-by: Johan Hovold Reviewed-by: Konrad Dybcio Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

cpuidle: menu: Avoid discarding useful information

2025-06-04T12:40:11+00:00

[ Upstream commit 85975daeaa4d6ec560bfcd354fc9c08ad7f38888 ] When giving up on making a high-confidence prediction, get_typical_interval() always returns UINT_MAX which means that the next idle interval prediction will be based entirely on the time till the next timer. However, the information represented by the most recent intervals may not be completely useless in those cases. Namely, the largest recent idle interval is an upper bound on the recently observed idle duration, so it is reasonable to assume that the next idle duration is unlikely to exceed it. Moreover, this is still true after eliminating the suspected outliers if the sample set still under consideration is at least as large as 50% of the maximum sample set size. Accordingly, make get_typical_interval() return the current maximum recent interval value in that case instead of UINT_MAX. Signed-off-by: Rafael J. Wysocki Reported-by: Artem Bityutskiy Tested-by: Artem Bityutskiy Reviewed-by: Christian Loehle Tested-by: Christian Loehle Tested-by: Aboorva Devarajan Link: https://patch.msgid.link/7770672.EvYhyI6sBW@rjwysocki.net Signed-off-by: Sasha Levin

cpuidle: riscv-sbi: fix device node release in early exit of for_each_possible_cpu

2025-01-17T12:34:41+00:00

[ Upstream commit 7e25044b804581b9c029d5a28d8800aebde18043 ] The 'np' device_node is initialized via of_cpu_device_node_get(), which requires explicit calls to of_node_put() when it is no longer required to avoid leaking the resource. Instead of adding the missing calls to of_node_put() in all execution paths, use the cleanup attribute for 'np' by means of the __free() macro, which automatically calls of_node_put() when the variable goes out of scope. Given that 'np' is only used within the for_each_possible_cpu(), reduce its scope to release the nood after every iteration of the loop. Fixes: 6abf32f1d9c5 ("cpuidle: Add RISC-V SBI CPU idle driver") Reviewed-by: Andrew Jones Signed-off-by: Javier Carrasco Link: https://lore.kernel.org/r/20241116-cpuidle-riscv-sbi-cleanup-v3-1-a3a46372ce08@gmail.com Signed-off-by: Palmer Dabbelt Signed-off-by: Sasha Levin

cpuidle: Avoid potential overflow in integer multiplication

2024-04-13T11:04:54+00:00

[ Upstream commit 88390dd788db485912ee7f9a8d3d56fc5265d52f ] In detail: In C language, when you perform a multiplication operation, if both operands are of int type, the multiplication operation is performed on the int type, and then the result is converted to the target type. This means that if the product of int type multiplication exceeds the range that int type can represent, an overflow will occur even if you store the result in a variable of int64_t type. For a multiplication of two int values, it is better to use mul_u32_u32() rather than s->exit_latency_ns = s->exit_latency * NSEC_PER_USEC to avoid potential overflow happenning. Signed-off-by: C Cheng Signed-off-by: Bo Ye Reviewed-by: AngeloGioacchino Del Regno [ rjw: New subject ] Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT

2023-09-13T07:42:48+00:00

[ Upstream commit eac030b22ea12cdfcbb2e941c21c03964403c63f ] lppaca_shared_proc() takes a pointer to the lppaca which is typically accessed through get_lppaca(). With DEBUG_PREEMPT enabled, this leads to checking if preemption is enabled, for example: BUG: using smp_processor_id() in preemptible [00000000] code: grep/10693 caller is lparcfg_data+0x408/0x19a0 CPU: 4 PID: 10693 Comm: grep Not tainted 6.5.0-rc3 #2 Call Trace: dump_stack_lvl+0x154/0x200 (unreliable) check_preemption_disabled+0x214/0x220 lparcfg_data+0x408/0x19a0 ... This isn't actually a problem however, as it does not matter which lppaca is accessed, the shared proc state will be the same. vcpudispatch_stats_procfs_init() already works around this by disabling preemption, but the lparcfg code does not, erroring any time /proc/powerpc/lparcfg is accessed with DEBUG_PREEMPT enabled. Instead of disabling preemption on the caller side, rework lppaca_shared_proc() to not take a pointer and instead directly access the lppaca, bypassing any potential preemption checks. Fixes: f13c13a00512 ("powerpc: Stop using non-architected shared_proc field in lppaca") Signed-off-by: Russell Currey [mpe: Rework to avoid needing a definition in paca.h and lppaca.h] Signed-off-by: Michael Ellerman Link: https://msgid.link/20230823055317.751786-4-mpe@ellerman.id.au Signed-off-by: Sasha Levin