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Date: Wed, 9 Jun 2021 23:07:26 -0400
From: Qian Cai <quic_qiancai@...cinc.com>
To: Viresh Kumar <viresh.kumar@...aro.org>,
Rafael Wysocki <rjw@...ysocki.net>,
Ben Segall <bsegall@...gle.com>,
Catalin Marinas <catalin.marinas@....com>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Ingo Molnar <mingo@...hat.com>,
Juri Lelli <juri.lelli@...hat.com>,
Mel Gorman <mgorman@...e.de>,
Peter Zijlstra <peterz@...radead.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>,
Sudeep Holla <sudeep.holla@....com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Will Deacon <will@...nel.org>
CC: <linux-pm@...r.kernel.org>,
Ionela Voinescu <ionela.voinescu@....com>,
<linux-acpi@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V6 0/4] cpufreq: cppc: Add support for frequency
invariance
On 6/9/2021 11:46 AM, Qian Cai wrote:
>
>
> On 3/10/2021 12:23 AM, Viresh Kumar wrote:
>> Hello,
>>
>> CPPC cpufreq driver is used for ARM servers and this patch series tries
>> to provide counter-based frequency invariance support for them in the
>> absence for architecture specific counters (like AMUs).
>>
>> This is tested by:
>> - Vincent Guittot on ThunderX2.
>> - Ionela Voinescu on Juno R2.
>> - /me with hacks on Hikey, as I don't have access to the right hardware.
>
> Git blame pointed out this series for a use-after-free during CPU offline/online. Any thoughts?
FYI, it could trigger a linked-list corruption instead below sometimes.
Reverting only the 4th patch (cpufreq: CPPC: Add support for frequency invariance) alone fixed the use-after-free. The corruption seems gone as well.
[ 258.585467][ T704] WARNING: CPU: 1 PID: 704 at drivers/cpufreq/cppc_cpufreq.c:124 cppc_scale_freq_workfn+0x2d0/0x368 [cppc_cpufreq]
[ 258.593303][ C13] list_add corruption. prev->next should be next (ffff0008d88e6e48), but was ffff009b676bed30. (prev=ffff009b676bed30).
[ 259.155595][ C13] Call trace:
[ 259.158727][ C13] __list_add_valid+0xf0/0xf8
[ 259.163251][ C13] kthread_insert_work+0x114/0x5c8
[ 259.168209][ C13] kthread_queue_work+0xf8/0x138
[ 259.172993][ C13] cppc_irq_work+0x24/0x30 [cppc_cpufreq]
[ 259.178566][ C13] irq_work_single+0xec/0x1e0
[ 259.183091][ C13] irq_work_run_list+0x88/0xb8
[ 259.187701][ C13] irq_work_run+0x28/0x48
[ 259.191876][ C13] ipi_handler+0x3dc/0x7a0
[ 259.196140][ C13] handle_percpu_devid_irq+0x240/0xb70
[ 259.201447][ C13] handle_domain_irq+0xe4/0x168
[ 259.206144][ C13] gic_handle_irq+0x5c/0x150
[ 259.210582][ C13] do_interrupt_handler+0x58/0xa8
[ 259.215453][ C13] el1_interrupt+0x30/0x48
[ 259.219717][ C13] el1h_64_irq_handler+0x18/0x28
[ 259.224502][ C13] el1h_64_irq+0x74/0x78
[ 259.228590][ C13] _stext+0x264/0x1114
[ 259.232504][ C13] irq_exit+0x53c/0x610
[ 259.236507][ C13] handle_domain_irq+0xe8/0x168
[ 259.241203][ C13] gic_handle_irq+0x5c/0x150
[ 259.245640][ C13] call_on_irq_stack+0x28/0x50
[ 259.250250][ C13] do_interrupt_handler+0x80/0xa8
[ 259.255120][ C13] el1_interrupt+0x30/0x48
[ 259.259383][ C13] el1h_64_irq_handler+0x18/0x28
[ 259.264167][ C13] el1h_64_irq+0x74/0x78
[ 259.268255][ C13] cpuidle_enter_state+0x2a4/0xff0
[ 259.273214][ C13] cpuidle_enter+0x60/0xb0
[ 259.277476][ C13] call_cpuidle+0x44/0xc0
[ 259.281652][ C13] do_idle+0x36c/0x420
[ 259.285568][ C13] cpu_startup_entry+0x30/0x88
[ 259.290177][ C13] secondary_start_kernel+0x28c/0x2d8
[ 259.295395][ C13] __secondary_switched+0x90/0x94
[ 259.300269][ C13] Code: aa0103e3 91020000 aa1303e1 941b5a28 (d4210000)
[ 259.307049][ C13] ---[ end trace dabb4391495b1abe ]---
[ 259.312353][ C13] Kernel panic - not syncing: Oops - BUG: Fatal exception in interrupt
>
> cppc_scale_freq_workfn+0x2e8/0x368:
> cppc_perf_from_fbctrs at /usr/src/linux-next/drivers/cpufreq/cppc_cpufreq.c:584
> (inlined by) cppc_scale_freq_workfn at /usr/src/linux-next/drivers/cpufreq/cppc_cpufreq.c:119
>
> [ 9334.586904][ T694] BUG: KASAN: use-after-free in cppc_scale_freq_workfn+0x2e8/0x368 [cppc_cpufreq]
> [ 9334.595966][ T694] Read of size 4 at addr ffff0008d52557b4 by task cppc_fie/694
> [ 9334.603360][ T694]
> [ 9334.605543][ T694] CPU: 2 PID: 694 Comm: cppc_fie Tainted: G W 5.13.0-rc5-next-20210609+ #19
> [ 9334.615368][ T694] Hardware name: MiTAC RAPTOR EV-883832-X3-0001/RAPTOR, BIOS 1.6 06/28/2020
> [ 9334.623888][ T694] Call trace:
> [ 9334.627025][ T694] dump_backtrace+0x0/0x3b8
> [ 9334.631385][ T694] show_stack+0x20/0x30
> [ 9334.635394][ T694] dump_stack_lvl+0x144/0x190
> [ 9334.639925][ T694] print_address_description.constprop.0+0x74/0x3c8
> [ 9334.646368][ T694] kasan_report+0x1f0/0x208
> [ 9334.650724][ T694] __asan_report_load4_noabort+0x34/0x60
> [ 9334.656208][ T694] cppc_scale_freq_workfn+0x2e8/0x368 [cppc_cpufreq]
> [ 9334.662740][ T694] kthread_worker_fn+0x2f0/0xda0
> [ 9334.667532][ T694] kthread+0x3ac/0x460
> [ 9334.671453][ T694] ret_from_fork+0x10/0x18
> [ 9334.675722][ T694]
> [ 9334.677904][ T694] Allocated by task 607:
> [ 9334.681996][ T694] kasan_save_stack+0x28/0x58
> [ 9334.686525][ T694] 94] cppc_cpufre7164][ T694] cpufreq_add_dev+0x164/0x1b8
> [ 9334.711779][ T694] subsys_interface_register+0x218/0x360
> [ 9334.717265][ T694] cpufreq_register_driver+0x2a4/0x4c0
> [ 9334.722577][ T694] 0xffff80000af902a4
> [ 9334.726412][ T694] do_one_initcall+0x170/0xb98
> [ 9334.731029][ T694] do_init_module+0x18c/0x648
> [ 9334.735559][ T694] load_module+0x2618/0x3240
> [ 9334.740001][ T694] __do_sys_finit_module+0x118/0x1a8
> [ 9334.745138][ T694] __arm64_sys_finit_module+0x74/0xa8
> [ 9334.750360][ T694] invoke_syscall.constprop.0+0xdc/0x1d8
> [ 9334.755846][ T694] do_el0_svc+0x1f8/0x298
> [ 9334.760028][ T694] el0_svc+0x20/0x30
> [ 9334.763775][ T694] el0t_64_sync_handler+0xb0/0xb8
> [ 9334.768651][ T694] el0t_64_sync+0x178/0x17c
> [ 9334.773006][ T694]
> [ 9334.775187][ T694] The buggy address belongs to the object at ffff0008d5255780
> [ 9334.775187][ T694] which belongs to the cache kmalloc-128 of size 128
> [ 9334.789089][ T694] The buggy address is located 52 bytes inside of
> [ 9334.789089][ T694] 128-byte region [ffff0008d5255780, ffff0008d5255800)
> [ 9334.802125][ T694] The buggy address belongs to the page:
> [ 9334.807606][ T694] page:ffffffc002354940 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff0008d5255780 pfn:0x95525
> [ 9334.818907][ T694] flags: 0x7ffff800000200(slab|node=0|zone=0|lastcpupid=0xfffff)
> [ 9334.826480][ T694] raw: 007ffff800000200 ffff000012900448 ffffffc00240f8c8 ffff000012910580
> [ 9334.834915][ T694] raw: ffff0008d5255780 0000000000aa00a9 00000001ffffffff 0000000000000000
> [ 9334.843347][ T694] page dumped because: kasan: bad access detected
> [ 9334.849609][ T694]
> [ 9334.851790][ T694] Memory state around the buggy address:
> [ 9334.857272][ T694] ffff0008d5255680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 9334.865184][ T694] ffff0008d5255700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 9334.873096][ T694] >ffff0008d5255780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> [ 9334.881007][ T694] ^
> [ 9334.886489][ T694] ffff0008d5255800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 9334.894401][ T694] ffff0008d5255880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 9334.902312][ T694] ==================================================================
> [ 9334.910223][ T694] Disabling lock debugging due to kernel taint
> [ 9334.916638][T62553] CPU1: shutdown
> [ 9334.920044][T62553] psci: CPU1 killed (polled 0 ms)
> [ 9335.175037][ T22] IRQ 326: no longer affine to CPU2
> [ 9335.180136][ T22] IRQ 382: no longer affine to CPU2
> [ 9335.185320][T62553] CPU2: shutdown
> [ 9335.188751][T62553] psci: CPU2 killed (polled 0 ms)
> [ 9335.469684][ T27] IRQ 327: no longer affine to CPU3
> [ 9335.474792][ T27] IRQ 361: no longer affine to CPU3
> [ 9335.479938][T62553] CPU3: shutdown
> [ 9335.483344][T62553] psci: CPU3 killed (polled 0 ms)
> [ 9335.797240][ T32] IRQ 15: no longer affine to CPU4
> [ 9335.802343][ T32] IRQ 334: no longer affine to CPU4
> [ 9335.807554][T62553] CPU4: shutdown
> [ 9335.810973][T62553] psci: CPU4 killed (polled 0 ms)
> [ 9336.064091][T62553] CPU5: shutdown
> [ 9336.067529][T62553] psci: CPU5 killed (polled 0 ms)
> [ 9336.346263][T62553] CPU6: shutdown
> [ 9336.349668][T62553] psci: CPU6 killed (polled 0 ms)
> [ 9336.586727][T62553] CPU7: shutdown
> [ 9336.590140][T62553] psci: CPU7 killed (polled 0 ms)
> [ 9336.846866][T62553] CPU8: shutdown
> [ 9336.850273][T62553] psci: CPU8 killed (polled 0 ms)
> [ 9357.773249][T62671] loop0: detected capacity change from 0 to 8
> [ 9471.525541][ T191] INFO: task cpuhp/9:56 blocked for more than 122 seconds.
> [ 9471.532603][ T191] Tainted: G B W 5.13.0-rc5-next-20210609+ #19
> [ 9471.540291][ T191] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 9471.548837][ T191] task:cpuhp/9 state:D stack:58816 pid: 56 ppid: 2 flags:0x00000008
> [ 9471.557924][ T191] Call trace:
> [ 9471.561063][ T191] __switch_to+0x184/0x400
> [ 9471.565338][ T191] __schedule+0x744/0x1930
> [ 9471.569632][ T191] schedule+0x1d0/0x3e8
> [ 9471.573641][ T191] schedule_timeout+0x188/0x1f8
> [ 9471.578380][ T191] wait_for_completion+0x15c/0x270
> [ 9471.583348][ T191] kthread_flush_work+0x15c/0x248
> [ 9471.588274][ T191] __kthread_cancel_work_sync+0x1a0/0x230
> [ 9471.593851][ T191] kthread_cancel_work_sync+0x1c/0x28
> [ 9471.599114][ T191] sugov_stop+0x104/0x148
> [ 9471.603302][ T191] cpufreq_stop_governor+0x78/0x138
> [ 9471.608390][ T191] cpufreq_offline+0x7c/0x748
> [ 9471.612924][ T191] cpuhp_cpufreq_offline+0x18/0x28
> [ 9471.617924][ T191] cpuhp_invoke_callback+0x54c/0x2be0
> [ 9471.623153][ T191] cpuhp_thread_fun+0x204/0x588
> [ 9471.627892][ T191] smpboot_thread_fn+0x3c8/0xbf8
> [ 9471.632687][ T191] kthread+0x3ac/0x460
> [ 9471.636646][ T191] ret_from_fork+0x10/0x18
> [ 9471.640998][ T191] INFO: task irqbalance:940 blocked for more than 122 seconds.
> [ 9471.648437][ T191] Tainted: G B W 5.13.0-rc5-next-20210609+ #19
> [ 9471.656127][ T191] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 9471.664650][ T191] task:irqbalance state:D stack:55696 pid: 940 ppid: 1 flags:0x00000800
> [ 9471.673753][ T191] Call trace:
> [ 9471.676931][ T191] __switch_to+0x184/0x400
> [ 9471.681207][ T191] __schedule+0x744/0x1930
> [ 9471.685513][ T191] schedule+0x1d0/0x3e8
> [ 9471.689526][ T191] schedule_preempt_disabled+0x80/0x110
> [ 9471.694925][ T191] __mutex_lock+0x618/0x1330
> [ 9471.699401][ T191] mutex_lock_nested+0x6c/0xc0
> [ 9471.704024][ T191] online_show+0x34/0xa8
> [ 9471.708167][ T191] dev_attr_show+0x50/0xc8
> [ 9471.712442][ T191] sysfs_kf_seq_show+0x164/0x368
> [ 9471.717271][ T191] kernfs_seq_show+0x130/0x198
> [ 9471.721893][ T191] seq_read_iter+0x344/0xd50
> [ 9471.726371][ T191] kernfs_fop_read_iter+0x32c/0x4a8
> [ 9471.731426][ T191] new_sync_read+0x2bc/0x4e8
> [ 9471.735905][ T191] vfs_read+0x18c/0x340
> [ 9471.739918][ T191] ksys_read+0xf8/0x1e0
> [ 9471.743927][ T191] __arm64_sys_read+0x74/0xa8
> [ 9471.748479][ T191] invoke_syscall.constprop.0+0xdc/0x1d8
> [ 9471.753967][ T191] do_el0_svc+0x1f8/0x298
> [ 9471.758168][ T191] el0_svc+0x20/0x30
> [ 9471.761916][ T191] el0t_64_sync_handler+0xb0/0xb8
> [ 9471.766828][ T191] el0t_64_sync+0x178/0x17c
> [ 9471.771209][ T191] INFO: task kworker/9:2:27306 blocked for more than 123 seconds.
> [ 9471.778895][ T191] Tainted: G B W 5.13.0-rc5-next-20210609+ #19
> [ 9471.786574][ T191] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 9471.795094][ T191] task:kworker/9:2 state:D stack:57552 pid:27306 ppid: 2 flags:0x00000008
> [ 9471.804179][ T191] Workqueue: events cpuset_hotplug_workfn
> [ 9471.809782][ T191] Call trace:
> [ 9471.812919][ T191] __switch_to+0x184/0x400
> [ 9471.817208][ T191] __schedule+0x744/0x1930
> [ 9471.821479][ T191] schedule+0x1d0/0x3e8
> [ 9471.825512][ T191] percpu_rwsem_wait+0x1a4/0x320
> [ 9471.830303][ T191] __percpu_down_read+0xb0/0x148
> [ 9471.835089][ T191] cpus_read_lock+0x2b4/0x308
> [ 9471.839635][ T191] rebuild_sched_domains+0x24/0x50
> [ 9471.844598][ T191] cpuset_hotplug_workfn+0x21c/0x11e0
> [ 9471.849839][ T191] process_one_work+0x7e4/0x1998
> [ 9471.854629][ T191] worker_thread+0x334/0xad0
> [ 9471.859089][ T191] kthread+0x3ac/0x460
> [ 9471.863011][ T191] ret_from_fork+0x10/0x18
> [ 9471.867318][ T191] INFO: task kworker/31:1:49260 blocked for more than 123 seconds.
> [ 9471.875058][ T191] Tainted: G B W 5.13.0-rc5-next-20210609+ #19
> [ 9471.882732][ T191] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 9471.891280][ T191] task:kworker/31:1 state:D stack:60640 pid:49260 ppid: 2 flags:0x00000008
> [ 9471.900366][ T191] Workqueue: events vmstat_shepherd
> [ 9471.905425][ T191] Call trace:
> [ 9471.908582][ T191] __switch_to+0x184/0x400
> [ 9471.912853][ T191] __schedule+0x744/0x1930
> [ 9471.917142][ T191] schedule+0x1d0/0x3e8
> [ 9471.921150][ T191] percpu_rwsem_wait+0x1a4/0x320
> [ 9471.925960][ T191] __percpu_down_read+0xb0/0x148
> [ 9471.930751][ T191] cpus_read_lock+0x2b4/0x308
> [ 9471.935277][ T191] vmstat_shepherd+0x5c/0x1a8
> [ 9471.939828][ T191] process_one_work+0x7e4/0x1998
> [ 9471.944618][ T191] worker_thread+0x334/0xad0
> [ 9471.949084][ T191] kthread+0x3ac/0x460
> [ 9471.953007][ T191] ret_from_fork+0x10/0x18
> [ 9471.957305][ T191] INFO: task cpuhotplug04.sh:62553 blocked for more than 123 seconds.
> [ 9471.965306][ T191] Tainted: G B W 5.13.0-rc5-next-20210609+ #19
> [ 9471.972991][ T191] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 9471.981538][ T191] task:cpuhotplug04.sh state:D stack:55936 pid:62553 ppid: 7301 flags:0x00000000
> [ 9471.990625][ T191] Call trace:
> [ 9471.993764][ T191] __switch_to+0x184/0x400
> [ 9471.998053][ T191] __schedule+0x744/0x1930
> [ 9472.002322][ T191] schedule+0x1d0/0x3e8
> [ 9472.006352][ T191] schedule_timeout+0x188/0x1f8
> [ 9472.011056][ T191] wait_for_completion+0x15c/0x270
> [ 9472.016038][ T191] __cpuhp_kick_ap+0x158/0x1a8
> [ 9472.020656][ T191] cpuhp_kick_ap+0x200/0x7f8
> [ 9472.025095][ T191] cpuhp_kick_ap_work+0x1f0/0xc98
> [ 9472.029990][ T191] _cpu_down.constprop.0+0x348/0x1118
> [ 9472.035214][ T191] cpu_down+0x50/0x80
> [ 9472.039065][ T191] cpu_device_down+0x4c/0x68
> [ 9472.043507][ T191] cpu_subsys_offline+0x18/0x28
> [ 9472.048229][ T191] device_offline+0x154/0x1e0
> [ 9472.052757][ T191] online_store+0xa4/0x118
> [ 9472.057042][ T191] dev_attr_store+0x44/0x78
> [ 9472.061397][ T191] sysfs_kf_write+0xe8/0x138
> [ 9472.065867][ T191] kernfs_fop_write_iter+0x26c/0x3d0
> [ 9472.071006][ T191] new_sync_write+0x2bc/0x4f8
> [ 9472.075554][ T191] vfs_write+0x718/0xc88
> [ 9472.079649][ T191] ksys_write+0xf8/0x1e0
> [ 9472.083742][ T191] __arm64_sys_write+0x74/0xa8
> [ 9472.088374][ T191] invoke_syscall.constprop.0+0xdc/0x1d8
> [ 9472.093859][ T191] do_el0_svc+0xe4/0x298
> [ 9472.097971][ T191] el0_svc+0x20/0x30
> [ 9472.101718][ T191] el0t_64_sync_handler+0xb0/0xb8
> [ 9472.106610][ T191] el0t_64_sync+0x178/0x17c
> [ 9472.110972][ T191] INFO: lockdep is turned off.
> [ 9594.405358][ T191] INFO: task cpuhp/9:56 blocked for more than 245 seconds.
> [ 9594.412416][ T191] Tainted: G B W 5.13.0-rc5-next-20210609+ #19
> [ 9594.420107][ T191] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 9594.428651][ T191] task:cpuhp/9 state:D stack:58816 pid: 56 ppid: 2 flags:0x00000008
> [ 9594.437737][ T191] Call trace:
> [ 9594.440877][ T191] __switch_to+0x184/0x400
> [ 9594.445148][ T191] __schedule+0x744/0x1930
> [ 9594.449438][ T191] schedule+0x1d0/0x3e8
> [ 9594.453447][ T191] schedule_timeout+0x188/0x1f8
> [ 9594.458169][ T191] wait_for_completion+0x15c/0x270
> [ 9594.463133][ T191] kthread_flush_work+0x15c/0x248
> [ 9594.468038][ T191] __kthread_cancel_work_sync+0x1a0/0x230
> [ 9594.473611][ T191] kthread_cancel_work_sync+0x1c/0x28
> [ 9594.478853][ T191] sugov_stop+0x104/0x148
> [ 9594.483036][ T191] cpufreq_stop_governor+0x78/0x138
> [ 9594.488106][ T191] cpufreq_offline+0x7c/0x748
> [ 9594.492634][ T191] cpuhp_cpufreq_offline+0x18/0x28
> [ 9594.497616][ T191] cpuhp_invoke_callback+0x54c/0x2be0
> [ 9594.502840][ T191] cpuhp_thread_fun+0x204/0x588
> [ 9594.507559][ T191] smpboot_thread_fn+0x3c8/0xbf8
> [ 9594.512349][ T191] kthread+0x3ac/0x460
> [ 9594.516291][ T191] ret_from_fork+0x10/0x18
>
>
>>
>> This is based of 5.12-rc2. I will merge these via the arm-cpufreq tree
>> directly.
>>
>> Changes since V5:
>> - New patch to rename freq_scale to arch_freq_scale (Will Deacon).
>> - Separate patch to export arch_freq_scale and helpers (Will Deacon).
>> - Some improvements in the last patch like commit log, moving more stuff
>> to policy init, new fie_disabled flag, etc. (Ionela Voinescu).
>> - Added Reviewed/Acked/Tested-by tags.
>>
>> Changes since V4:
>> - Move some code to policy specific initialization for cppc driver.
>> - Initialize kthread specific stuff only once in cppc driver.
>> - Added a kerneldoc comment in cppc driver and improved changelog as
>> well.
>>
>> Changes since V3:
>> - rebuild_sched_domains_energy() stuff moved from arm64 to drivers/base.
>> - Added Reviewed/Tested-by Ionela for the first patch.
>> - Remove unused max_freq field from structure in cppc driver.
>> - s/cppc_f_i/cppc_freq_inv.
>> - Fix an per-cpu access, there was a bug in earlier version.
>> - Create a single kthread which can run on any CPU and takes care of
>> work from all the CPUs.
>> - Do the whole FIE thing under a new CONFIG option for cppc driver.
>> - Few minor improvements.
>>
>> Changes since V2:
>> - Not sending as an RFC anymore.
>> - Several renames, reordering of code in 1/2 based on Ionela's comments.
>> - Several rebase changes for 2/2.
>> - The freq_scale calculations are optimized a bit.
>> - Better overall commenting and commit logs.
>>
>> Changes since V1:
>> - The interface for setting the callbacks is improved, so different
>> parts looking to provide their callbacks don't need to think about
>> each other.
>>
>> - Moved to per-cpu storage for storing the callback related data, AMU
>> counters have higher priority with this.
>>
>> --
>> Viresh
>>
>> Viresh Kumar (4):
>> arch_topology: Rename freq_scale as arch_freq_scale
>> arch_topology: Allow multiple entities to provide sched_freq_tick()
>> callback
>> arch_topology: Export arch_freq_scale and helpers
>> cpufreq: CPPC: Add support for frequency invariance
>>
>> arch/arm64/include/asm/topology.h | 10 +-
>> arch/arm64/kernel/topology.c | 109 +++++--------
>> drivers/base/arch_topology.c | 89 ++++++++++-
>> drivers/cpufreq/Kconfig.arm | 10 ++
>> drivers/cpufreq/cppc_cpufreq.c | 245 ++++++++++++++++++++++++++++--
>> include/linux/arch_topology.h | 19 ++-
>> kernel/sched/core.c | 1 +
>> 7 files changed, 385 insertions(+), 98 deletions(-)
>>
>>
>> base-commit: a38fd8748464831584a19438cbb3082b5a2dab15
>>
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