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8ae954caf4
linux/drivers/clocksource
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Niklas Söderlund 8ae954caf4 clocksource/drivers/sh_cmt: Fix potential deadlock when calling runtime PM 
The ch->lock is used to protect the whole enable() and read() of
sh_cmt's implementation of struct clocksource. The enable()
implementation calls pm_runtime_get_sync() which may result in the clock
source to be read() triggering a cyclic lockdep warning for the
ch->lock.

The sh_cmt driver implement its own balancing of calls to
sh_cmt_{enable,disable}() with flags in sh_cmt_{start,stop}(). It does
this to deal with that start and stop are shared between the clock
source and clock event providers. While this could be improved on
verifying corner cases based on any substantial rework on all devices
this driver supports might prove hard.

As a first step separate the PM handling for clock event and clock
source. Always put/get the device when enabling/disabling the clock
source but keep the clock event logic unchanged. This allows the sh_cmt
implementation of struct clocksource to call PM without holding the
ch->lock and avoiding the deadlock.

Triggering and log of the deadlock warning,

  # echo e60f0000.timer > /sys/devices/system/clocksource/clocksource0/current_clocksource
  [   46.948370] ======================================================
  [   46.954730] WARNING: possible circular locking dependency detected
  [   46.961094] 5.10.0-rc6-arm64-renesas-00001-g0e5fd7414e8b #36 Not tainted
  [   46.967985] ------------------------------------------------------
  [   46.974342] migration/0/11 is trying to acquire lock:
  [   46.979543] ffff0000403ed220 (&dev->power.lock){-...}-{2:2}, at: __pm_runtime_resume+0x40/0x74
  [   46.988445]
  [   46.988445] but task is already holding lock:
  [   46.994441] ffff000040ad0298 (&ch->lock){....}-{2:2}, at: sh_cmt_start+0x28/0x210
  [   47.002173]
  [   47.002173] which lock already depends on the new lock.
  [   47.002173]
  [   47.010573]
  [   47.010573] the existing dependency chain (in reverse order) is:
  [   47.018262]
  [   47.018262] -> #3 (&ch->lock){....}-{2:2}:
  [   47.024033]        lock_acquire.part.0+0x120/0x330
  [   47.028970]        lock_acquire+0x64/0x80
  [   47.033105]        _raw_spin_lock_irqsave+0x7c/0xc4
  [   47.038130]        sh_cmt_start+0x28/0x210
  [   47.042352]        sh_cmt_clocksource_enable+0x28/0x50
  [   47.047644]        change_clocksource+0x9c/0x160
  [   47.052402]        multi_cpu_stop+0xa4/0x190
  [   47.056799]        cpu_stopper_thread+0x90/0x154
  [   47.061557]        smpboot_thread_fn+0x244/0x270
  [   47.066310]        kthread+0x154/0x160
  [   47.070175]        ret_from_fork+0x10/0x20
  [   47.074390]
  [   47.074390] -> #2 (tk_core.seq.seqcount){----}-{0:0}:
  [   47.081136]        lock_acquire.part.0+0x120/0x330
  [   47.086070]        lock_acquire+0x64/0x80
  [   47.090203]        seqcount_lockdep_reader_access.constprop.0+0x74/0x100
  [   47.097096]        ktime_get+0x28/0xa0
  [   47.100960]        hrtimer_start_range_ns+0x210/0x2dc
  [   47.106164]        generic_sched_clock_init+0x70/0x88
  [   47.111364]        sched_clock_init+0x40/0x64
  [   47.115853]        start_kernel+0x494/0x524
  [   47.120156]
  [   47.120156] -> #1 (hrtimer_bases.lock){-.-.}-{2:2}:
  [   47.126721]        lock_acquire.part.0+0x120/0x330
  [   47.136042]        lock_acquire+0x64/0x80
  [   47.144461]        _raw_spin_lock_irqsave+0x7c/0xc4
  [   47.153721]        hrtimer_start_range_ns+0x68/0x2dc
  [   47.163054]        rpm_suspend+0x308/0x5dc
  [   47.171473]        rpm_idle+0xc4/0x2a4
  [   47.179550]        pm_runtime_work+0x98/0xc0
  [   47.188209]        process_one_work+0x294/0x6f0
  [   47.197142]        worker_thread+0x70/0x45c
  [   47.205661]        kthread+0x154/0x160
  [   47.213673]        ret_from_fork+0x10/0x20
  [   47.221957]
  [   47.221957] -> #0 (&dev->power.lock){-...}-{2:2}:
  [   47.236292]        check_noncircular+0x128/0x140
  [   47.244907]        __lock_acquire+0x13b0/0x204c
  [   47.253332]        lock_acquire.part.0+0x120/0x330
  [   47.262033]        lock_acquire+0x64/0x80
  [   47.269826]        _raw_spin_lock_irqsave+0x7c/0xc4
  [   47.278430]        __pm_runtime_resume+0x40/0x74
  [   47.286758]        sh_cmt_start+0x84/0x210
  [   47.294537]        sh_cmt_clocksource_enable+0x28/0x50
  [   47.303449]        change_clocksource+0x9c/0x160
  [   47.311783]        multi_cpu_stop+0xa4/0x190
  [   47.319720]        cpu_stopper_thread+0x90/0x154
  [   47.328022]        smpboot_thread_fn+0x244/0x270
  [   47.336298]        kthread+0x154/0x160
  [   47.343708]        ret_from_fork+0x10/0x20
  [   47.351445]
  [   47.351445] other info that might help us debug this:
  [   47.351445]
  [   47.370225] Chain exists of:
  [   47.370225]   &dev->power.lock --> tk_core.seq.seqcount --> &ch->lock
  [   47.370225]
  [   47.392003]  Possible unsafe locking scenario:
  [   47.392003]
  [   47.405314]        CPU0                    CPU1
  [   47.413569]        ----                    ----
  [   47.421768]   lock(&ch->lock);
  [   47.428425]                                lock(tk_core.seq.seqcount);
  [   47.438701]                                lock(&ch->lock);
  [   47.447930]   lock(&dev->power.lock);
  [   47.455172]
  [   47.455172]  *** DEADLOCK ***
  [   47.455172]
  [   47.471433] 3 locks held by migration/0/11:
  [   47.479099]  #0: ffff8000113c9278 (timekeeper_lock){-.-.}-{2:2}, at: change_clocksource+0x2c/0x160
  [   47.491834]  #1: ffff8000113c8f88 (tk_core.seq.seqcount){----}-{0:0}, at: multi_cpu_stop+0xa4/0x190
  [   47.504727]  #2: ffff000040ad0298 (&ch->lock){....}-{2:2}, at: sh_cmt_start+0x28/0x210
  [   47.516541]
  [   47.516541] stack backtrace:
  [   47.528480] CPU: 0 PID: 11 Comm: migration/0 Not tainted 5.10.0-rc6-arm64-renesas-00001-g0e5fd7414e8b #36
  [   47.542147] Hardware name: Renesas Salvator-X 2nd version board based on r8a77965 (DT)
  [   47.554241] Call trace:
  [   47.560832]  dump_backtrace+0x0/0x190
  [   47.568670]  show_stack+0x14/0x30
  [   47.576144]  dump_stack+0xe8/0x130
  [   47.583670]  print_circular_bug+0x1f0/0x200
  [   47.592015]  check_noncircular+0x128/0x140
  [   47.600289]  __lock_acquire+0x13b0/0x204c
  [   47.608486]  lock_acquire.part.0+0x120/0x330
  [   47.616953]  lock_acquire+0x64/0x80
  [   47.624582]  _raw_spin_lock_irqsave+0x7c/0xc4
  [   47.633114]  __pm_runtime_resume+0x40/0x74
  [   47.641371]  sh_cmt_start+0x84/0x210
  [   47.649115]  sh_cmt_clocksource_enable+0x28/0x50
  [   47.657916]  change_clocksource+0x9c/0x160
  [   47.666165]  multi_cpu_stop+0xa4/0x190
  [   47.674056]  cpu_stopper_thread+0x90/0x154
  [   47.682308]  smpboot_thread_fn+0x244/0x270
  [   47.690560]  kthread+0x154/0x160
  [   47.697927]  ret_from_fork+0x10/0x20
  [   47.708447] clocksource: Switched to clocksource e60f0000.timer

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20201205021921.1456190-2-niklas.soderlund+renesas@ragnatech.se
2020-12-07 20:10:05 +01:00
..
acpi_pm.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 243 2019-06-19 17:09:07 +02:00
arc_timer.c clocksource/drivers/arc_timer: Remove duplicate error message 2020-05-22 23:58:56 +02:00
arm_arch_timer.c clocksource/drivers/arm_arch_timer: Correct fault programming of CNTKCTL_EL1.EVNTI 2020-12-05 19:34:04 +01:00
arm_global_timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
armv7m_systick.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
asm9260_timer.c clocksource/drivers/asm9260: Add a check for of_clk_get 2019-11-04 10:40:10 +01:00
bcm2835_timer.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
bcm_kona_timer.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
clksrc_st_lpc.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
clksrc-dbx500-prcmu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 197 2019-05-30 11:29:22 -07:00
clps711x-timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
dummy_timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
dw_apb_timer_of.c clocksource/drivers/dw_apb_timer_of: Add error handling if no clock available 2020-12-05 19:33:55 +01:00
dw_apb_timer.c clocksource: dw_apb_timer: Make CPU-affiliation being optional 2020-05-23 00:02:41 +02:00
em_sti.c clocksource/drivers/em_sti: Fix variable declaration in em_sti_probe 2020-01-16 19:06:57 +01:00
exynos_mct.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
h8300_timer8.c clocksource/drivers/h8300_timer8: Fix wrong return value in h8300_8timer_init() 2020-08-24 13:01:38 +02:00
h8300_timer16.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
h8300_tpu.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hyperv_timer.c hv: clocksource: Add notrace attribute to read_hv_sched_clock_*() functions 2020-09-28 09:04:48 +00:00
i8253.c clockevents/drivers/i8253: Add support for PIT shutdown quirk 2018-11-04 11:04:46 +01:00
ingenic-ost.c clocksource: Add driver for the Ingenic JZ47xx OST 2020-02-27 09:37:29 +01:00
ingenic-sysost.c clocksource/drivers/ingenic: Add support for the Ingenic X1000 OST. 2020-07-23 16:58:09 +02:00
ingenic-timer.c clocksource/drivers/ingenic: Fix section mismatch 2020-12-03 19:16:26 +01:00
jcore-pit.c
Kconfig clocksource/drivers/riscv: Make RISCV_TIMER depends on RISCV_SBI 2020-12-03 19:16:26 +01:00
Makefile clocksource/drivers/nps: Remove EZChip NPS clocksource driver 2020-12-03 19:16:18 +01:00
mips-gic-timer.c clocksource: mips-gic-timer: Mark GIC timer as unstable if ref clock changes 2020-05-23 00:03:16 +02:00
mmio.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
mps2-timer.c clocksource/drivers/mps2-timer: Use semicolons rather than commas to separate statements 2020-10-01 10:07:26 +02:00
mxs_timer.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
nomadik-mtu.c clocksource/drivers/nomadik-mtu: Handle 32kHz clock 2020-07-23 16:57:43 +02:00
numachip.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282 2019-06-05 17:36:37 +02:00
renesas-ostm.c clocksource/drivers/renesas-ostm: Use unique device name instead of ostm 2019-11-04 10:38:46 +01:00
samsung_pwm_timer.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
scx200_hrt.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sh_cmt.c clocksource/drivers/sh_cmt: Fix potential deadlock when calling runtime PM 2020-12-07 20:10:05 +01:00
sh_mtu2.c remove ioremap_nocache and devm_ioremap_nocache 2020-01-06 09:45:59 +01:00
sh_tmu.c remove ioremap_nocache and devm_ioremap_nocache 2020-01-06 09:45:59 +01:00
timer-armada-370-xp.c clocksource/drivers/armada-370-xp: Use semicolons rather than commas to separate statements 2020-10-02 16:27:28 +02:00
timer-atcpit100.c clocksource/drivers: Set clockevent device cpumask to cpu_possible_mask 2018-07-26 11:26:30 +02:00
timer-atlas7.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-atmel-pit.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
timer-atmel-st.c clocksource/drivers/atmel-st: Remove useless 'status' 2020-04-15 10:57:15 +02:00
timer-atmel-tcb.c clocksource/drivers/timer-atmel-tcb: Add sama5d2 support 2020-07-11 18:58:24 +02:00
timer-cadence-ttc.c clocksource/drivers/cadence_ttc: Fix memory leak in ttc_setup_clockevent() 2020-12-03 19:16:26 +01:00
timer-clint.c clocksource: clint: Export clint_time_val for modules 2020-09-29 23:55:27 -07:00
timer-cs5535.c clocksource/drivers/timer-cs5535: Request irq with non-NULL dev_id 2020-03-12 19:23:06 +01:00
timer-davinci.c clocksource: davinci: axe a pointless __GFP_NOFAIL 2020-04-09 12:13:20 +02:00
timer-digicolor.c
timer-efm32.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-fsl-ftm.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-fttmr010.c clocksource/drivers/fttmr010: Set interrupt and shutdown 2020-02-21 09:28:38 +01:00
timer-gx6605s.c clocksource/drivers/timer-gx6605s: Fixup counter reload 2020-08-24 13:01:39 +02:00
timer-imx-gpt.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-imx-sysctr.c clocksource/drivers/imx-sysctr: Remove unused includes 2020-03-17 10:11:45 +01:00
timer-imx-tpm.c clocksource/drivers/imx-tpm: Add support for ARM64 2020-04-09 16:24:50 +02:00
timer-integrator-ap.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-ixp4xx.c clocksource/drivers/ixp4xx: Implement delay timer 2019-06-25 19:49:18 +02:00
timer-keystone.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
timer-lpc32xx.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-mediatek.c clocksource/drivers/mediatek: Fix error handling 2019-10-16 17:04:50 +02:00
timer-meson6.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-microchip-pit64b.c clocksource/drivers/timer-microchip-pit64b: Fix rate for gck 2020-03-16 11:19:37 +01:00
timer-milbeaut.c clocksource/drivers/timer-milbeaut: Cleanup common register accesses 2019-05-02 21:55:58 +02:00
timer-mp-csky.c clocksource/drivers/c-sky: fixup ftrace call-graph panic 2018-12-31 23:17:23 +08:00
timer-npcm7xx.c clocksource/drivers/npcm: Fix GENMASK and timer operation 2019-08-27 00:31:39 +02:00
timer-of.c - Some cleanups for the timer-of, use %p0F and the unique device name 2019-11-04 18:49:13 +01:00
timer-of.h clocksource/drivers/timer-of: Store the device node pointer in 'struct timer_of' 2018-01-08 17:57:24 +01:00
timer-orion.c clocksource/drivers/orion: Add missing clk_disable_unprepare() on error path 2020-12-03 19:16:26 +01:00
timer-owl.c clocksource/drivers/owl: Improve owl_timer_init fail messages 2020-02-27 09:42:00 +01:00
timer-oxnas-rps.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 201 2019-05-30 11:29:52 -07:00
timer-pistachio.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-prima2.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-probe.c treewide: Convert macro and uses of __section(foo) to __section("foo") 2020-10-25 14:51:49 -07:00
timer-pxa.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-qcom.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282 2019-06-05 17:36:37 +02:00
timer-rda.c clocksource/drivers/rda: Add clock driver for RDA8810PL SoC 2018-12-18 22:22:23 +01:00
timer-riscv.c RISC-V: Remove CLINT related code from timer and arch 2020-08-20 10:58:13 -07:00
timer-rockchip.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
timer-sp804.c clocksource/drivers/sp804: Use pr_fmt 2020-12-03 19:16:18 +01:00
timer-sp.h clocksource/drivers/sp804: Enable Hisilicon sp804 timer 64bit mode 2020-09-24 10:51:04 +02:00
timer-sprd.c clocksource/drivers/sprd: Register one always-on timer to compensate suspend time 2018-07-26 11:26:34 +02:00
timer-stm32-lp.c clocksource: Add Low Power STM32 timers driver 2020-06-18 11:19:58 +01:00
timer-stm32.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
timer-sun4i.c clocksource: sun4i: Add missing compatibles 2019-08-27 00:31:39 +02:00
timer-sun5i.c clocksource/drivers/sun5i: Fail gracefully when clock rate is unavailable 2019-02-23 12:13:45 +01:00
timer-tango-xtal.c clocksource/drivers/tango-xtal: Rename the file for consistency 2019-02-23 12:13:45 +01:00
timer-tegra.c clocksource/drivers/tegra: Set up maximum-ticks limit properly 2019-06-25 19:49:18 +02:00
timer-ti-32k.c clocksource/drivers: Replace HTTP links with HTTPS ones 2020-07-23 16:57:43 +02:00
timer-ti-dm-systimer.c clocksource/drivers/timer-ti-dm: Do reset before enable 2020-08-24 13:01:39 +02:00
timer-ti-dm.c clocksource/drivers: Replace HTTP links with HTTPS ones 2020-07-23 16:57:43 +02:00
timer-u300.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-versatile.c clocksource/drivers/timer-versatile: Clear OF_POPULATED flag 2020-05-23 00:03:25 +02:00
timer-vf-pit.c clocksource/drivers/timer-vf-pit: Add missing parenthesis 2020-04-05 09:24:58 +02:00
timer-vt8500.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-zevio.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00