Date:   Mon, 3 Oct 2022 16:10:33 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>, rafael@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        rui.zhang@...el.com,
        Broadcom Kernel Team <bcm-kernel-feedback-list@...adcom.com>,
        Support Opensource <support.opensource@...semi.com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        Andy Gross <agross@...nel.org>,
        Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Alim Akhtar <alim.akhtar@...sung.com>, netdev@...r.kernel.org,
        platform-driver-x86@...r.kernel.org,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-omap@...r.kernel.org
Subject: Re: [PATCH v8 00/29] Rework the trip points creation

Hi Daniel,

On 03.10.2022 11:25, Daniel Lezcano wrote:
> This work is the pre-requisite of handling correctly when the trip
> point are crossed. For that we need to rework how the trip points are
> declared and assigned to a thermal zone.
>
> Even if it appears to be a common sense to have the trip points being
> ordered, this no guarantee neither documentation telling that is the
> case.
>
> One solution could have been to create an ordered array of trips built
> when registering the thermal zone by calling the different get_trip*
> ops. However those ops receive a thermal zone pointer which is not
> known as it is in the process of creating it.
>
> This cyclic dependency shows we have to rework how we manage the trip
> points.
>
> Actually, all the trip points definition can be common to the backend
> sensor drivers and we can factor out the thermal trip structure in all
> of them.
>
> Then, as we register the thermal trips array, they will be available
> in the thermal zone structure and a core function can return the trip
> given its id.
>
> The get_trip_* ops won't be needed anymore and could be removed. The
> resulting code will be another step forward to a self encapsulated
> generic thermal framework.
>
> Most of the drivers can be converted more or less easily. This series
> does a first round with most of the drivers. Some remain and will be
> converted but with a smaller set of changes as the conversion is a bit
> more complex.
>
> Changelog:
> v8:
> - Pretty oneline change and parenthesis removal (Rafael)
> - Collected tags
> v7:
> - Added missing return 0 in the x86_pkg_temp driver
> v6:
> - Improved the code for the get_crit_temp() function as suggested by 
> Rafael
> - Removed inner parenthesis in the set_trip_temp() function and invert the
> conditions. Check the type of the trip point is unchanged
> - Folded patch 4 with 1
> - Add per thermal zone info message in the bang-bang governor
> - Folded the fix for an uninitialized variable in 
> int340x_thermal_zone_add()
> v5:
> - Fixed a deadlock when calling thermal_zone_get_trip() while
> handling the thermal zone lock
> - Remove an extra line in the sysfs change
> - Collected tags
> v4:
> - Remove extra lines on exynos changes as reported by Krzysztof Kozlowski
> - Collected tags
> v3:
> - Reorg the series to be git-bisect safe
> - Added the set_trip generic function
> - Added the get_crit_temp generic function
> - Removed more dead code in the thermal-of
> - Fixed the exynos changelog
> - Fixed the error check for the exynos drivers
> - Collected tags
> v2:
> - Added missing EXPORT_SYMBOL_GPL() for thermal_zone_get_trip()
> - Removed tab whitespace in the acerhdf driver
> - Collected tags
>
> Cc: Raju Rangoju <rajur@...lsio.com>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Eric Dumazet <edumazet@...gle.com>
> Cc: Jakub Kicinski <kuba@...nel.org>
> Cc: Paolo Abeni <pabeni@...hat.com>
> Cc: Peter Kaestle <peter@...e.net>
> Cc: Hans de Goede <hdegoede@...hat.com>
> Cc: Mark Gross <markgross@...nel.org>
> Cc: Miquel Raynal <miquel.raynal@...tlin.com>
> Cc: "Rafael J. Wysocki" <rafael@...nel.org>
> Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
> Cc: Amit Kucheria <amitk@...nel.org>
> Cc: Zhang Rui <rui.zhang@...el.com>
> Cc: Nicolas Saenz Julienne <nsaenz@...nel.org>
> Cc: Broadcom Kernel Team <bcm-kernel-feedback-list@...adcom.com>
> Cc: Florian Fainelli <f.fainelli@...il.com>
> Cc: Ray Jui <rjui@...adcom.com>
> Cc: Scott Branden <sbranden@...adcom.com>
> Cc: Support Opensource <support.opensource@...semi.com>
> Cc: Lukasz Luba <lukasz.luba@....com>
> Cc: Shawn Guo <shawnguo@...nel.org>
> Cc: Sascha Hauer <s.hauer@...gutronix.de>
> Cc: Pengutronix Kernel Team <kernel@...gutronix.de>
> Cc: Fabio Estevam <festevam@...il.com>
> Cc: NXP Linux Team <linux-imx@....com>
> Cc: Thara Gopinath <thara.gopinath@...aro.org>
> Cc: Andy Gross <agross@...nel.org>
> Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
> Cc: "Niklas Söderlund" <niklas.soderlund@...natech.se>
> Cc: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> Cc: Alim Akhtar <alim.akhtar@...sung.com>
> Cc: Thierry Reding <thierry.reding@...il.com>
> Cc: Jonathan Hunter <jonathanh@...dia.com>
> Cc: Eduardo Valentin <edubezval@...il.com>
> Cc: Keerthy <j-keerthy@...com>
> Cc: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
> Cc: Masami Hiramatsu <mhiramat@...nel.org>
> Cc: Antoine Tenart <atenart@...nel.org>
> Cc: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
> Cc: Dmitry Osipenko <digetx@...il.com>
> Cc: netdev@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Cc: platform-driver-x86@...r.kernel.org
> Cc: linux-pm@...r.kernel.org
> Cc: linux-rpi-kernel@...ts.infradead.org
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-arm-msm@...r.kernel.org
> Cc: linux-renesas-soc@...r.kernel.org
> Cc: linux-samsung-soc@...r.kernel.org
> Cc: linux-tegra@...r.kernel.org
> Cc: linux-omap@...r.kernel.org
>
> Daniel Lezcano (29):
> thermal/core: Add a generic thermal_zone_get_trip() function
> thermal/sysfs: Always expose hysteresis attributes
> thermal/core: Add a generic thermal_zone_set_trip() function
> thermal/core/governors: Use thermal_zone_get_trip() instead of ops
> functions
> thermal/of: Use generic thermal_zone_get_trip() function
> thermal/of: Remove unused functions
> thermal/drivers/exynos: Use generic thermal_zone_get_trip() function
> thermal/drivers/exynos: of_thermal_get_ntrips()
> thermal/drivers/exynos: Replace of_thermal_is_trip_valid() by
> thermal_zone_get_trip()
> thermal/drivers/tegra: Use generic thermal_zone_get_trip() function
> thermal/drivers/uniphier: Use generic thermal_zone_get_trip() function
> thermal/drivers/hisi: Use generic thermal_zone_get_trip() function
> thermal/drivers/qcom: Use generic thermal_zone_get_trip() function
> thermal/drivers/armada: Use generic thermal_zone_get_trip() function
> thermal/drivers/rcar_gen3: Use the generic function to get the number
> of trips
> thermal/of: Remove of_thermal_get_ntrips()
> thermal/of: Remove of_thermal_is_trip_valid()
> thermal/of: Remove of_thermal_set_trip_hyst()
> thermal/of: Remove of_thermal_get_crit_temp()
> thermal/drivers/st: Use generic trip points
> thermal/drivers/imx: Use generic thermal_zone_get_trip() function
> thermal/drivers/rcar: Use generic thermal_zone_get_trip() function
> thermal/drivers/broadcom: Use generic thermal_zone_get_trip() function
> thermal/drivers/da9062: Use generic thermal_zone_get_trip() function
> thermal/drivers/ti: Remove unused macros ti_thermal_get_trip_value() /
> ti_thermal_trip_is_valid()
> thermal/drivers/acerhdf: Use generic thermal_zone_get_trip() function
> thermal/drivers/cxgb4: Use generic thermal_zone_get_trip() function
> thermal/intel/int340x: Replace parameter to simplify
> thermal/drivers/intel: Use generic thermal_zone_get_trip() function

I've tested this v8 patchset after fixing the issue with Exynos TMU with 
https://lore.kernel.org/all/20221003132943.1383065-1-daniel.lezcano@linaro.org/ 
patch and I got the following lockdep warning on all Exynos-based boards:


======================================================
WARNING: possible circular locking dependency detected
6.0.0-rc1-00083-ge5c9d117223e #12945 Not tainted
------------------------------------------------------
swapper/0/1 is trying to acquire lock:
c1ce66b0 (&data->lock#2){+.+.}-{3:3}, at: exynos_get_temp+0x3c/0xc8

but task is already holding lock:
c2979b94 (&tz->lock){+.+.}-{3:3}, at: 
thermal_zone_device_update.part.0+0x3c/0x528

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&tz->lock){+.+.}-{3:3}:
        mutex_lock_nested+0x1c/0x24
        thermal_zone_get_trip+0x20/0x44
        exynos_tmu_initialize+0x144/0x1e0
        exynos_tmu_probe+0x2b0/0x728
        platform_probe+0x5c/0xb8
        really_probe+0xe0/0x414
        __driver_probe_device+0xa0/0x208
        driver_probe_device+0x30/0xc0
        __driver_attach+0xf0/0x1f0
        bus_for_each_dev+0x70/0xb0
        bus_add_driver+0x174/0x218
        driver_register+0x88/0x11c
        do_one_initcall+0x64/0x380
        kernel_init_freeable+0x1c0/0x224
        kernel_init+0x18/0x12c
        ret_from_fork+0x14/0x2c
        0x0

-> #0 (&data->lock#2){+.+.}-{3:3}:
        lock_acquire+0x124/0x3e4
        __mutex_lock+0x90/0x948
        mutex_lock_nested+0x1c/0x24
        exynos_get_temp+0x3c/0xc8
        __thermal_zone_get_temp+0x5c/0x12c
        thermal_zone_device_update.part.0+0x78/0x528
        __thermal_cooling_device_register.part.0+0x298/0x354
        __cpufreq_cooling_register.constprop.0+0x138/0x218
        of_cpufreq_cooling_register+0x48/0x8c
        cpufreq_online+0x8d0/0xb2c
        cpufreq_add_dev+0xb0/0xec
        subsys_interface_register+0x108/0x118
        cpufreq_register_driver+0x15c/0x380
        dt_cpufreq_probe+0x2e4/0x434
        platform_probe+0x5c/0xb8
        really_probe+0xe0/0x414
        __driver_probe_device+0xa0/0x208
        driver_probe_device+0x30/0xc0
        __driver_attach+0xf0/0x1f0
        bus_for_each_dev+0x70/0xb0
        bus_add_driver+0x174/0x218
        driver_register+0x88/0x11c
        do_one_initcall+0x64/0x380
        kernel_init_freeable+0x1c0/0x224
        kernel_init+0x18/0x12c
        ret_from_fork+0x14/0x2c
        0x0

other info that might help us debug this:

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&tz->lock);
                                lock(&data->lock#2);
                                lock(&tz->lock);
   lock(&data->lock#2);

  *** DEADLOCK ***

5 locks held by swapper/0/1:
  #0: c1c8648c (&dev->mutex){....}-{3:3}, at: __driver_attach+0xe4/0x1f0
  #1: c1210434 (cpu_hotplug_lock){++++}-{0:0}, at: 
cpufreq_register_driver+0xc4/0x380
  #2: c1ed8298 (subsys mutex#8){+.+.}-{3:3}, at: 
subsys_interface_register+0x4c/0x118
  #3: c131f944 (thermal_list_lock){+.+.}-{3:3}, at: 
__thermal_cooling_device_register.part.0+0x238/0x354
  #4: c2979b94 (&tz->lock){+.+.}-{3:3}, at: 
thermal_zone_device_update.part.0+0x3c/0x528

stack backtrace:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.0.0-rc1-00083-ge5c9d117223e 
#12945
Hardware name: Samsung Exynos (Flattened Device Tree)
  unwind_backtrace from show_stack+0x10/0x14
  show_stack from dump_stack_lvl+0x58/0x70
  dump_stack_lvl from check_noncircular+0xf0/0x158
  check_noncircular from __lock_acquire+0x15e8/0x2a7c
  __lock_acquire from lock_acquire+0x124/0x3e4
  lock_acquire from __mutex_lock+0x90/0x948
  __mutex_lock from mutex_lock_nested+0x1c/0x24
  mutex_lock_nested from exynos_get_temp+0x3c/0xc8
  exynos_get_temp from __thermal_zone_get_temp+0x5c/0x12c
  __thermal_zone_get_temp from thermal_zone_device_update.part.0+0x78/0x528
  thermal_zone_device_update.part.0 from 
__thermal_cooling_device_register.part.0+0x298/0x354
  __thermal_cooling_device_register.part.0 from 
__cpufreq_cooling_register.constprop.0+0x138/0x218
  __cpufreq_cooling_register.constprop.0 from 
of_cpufreq_cooling_register+0x48/0x8c
  of_cpufreq_cooling_register from cpufreq_online+0x8d0/0xb2c
  cpufreq_online from cpufreq_add_dev+0xb0/0xec
  cpufreq_add_dev from subsys_interface_register+0x108/0x118
  subsys_interface_register from cpufreq_register_driver+0x15c/0x380
  cpufreq_register_driver from dt_cpufreq_probe+0x2e4/0x434
  dt_cpufreq_probe from platform_probe+0x5c/0xb8
  platform_probe from really_probe+0xe0/0x414
  really_probe from __driver_probe_device+0xa0/0x208
  __driver_probe_device from driver_probe_device+0x30/0xc0
  driver_probe_device from __driver_attach+0xf0/0x1f0
  __driver_attach from bus_for_each_dev+0x70/0xb0
  bus_for_each_dev from bus_add_driver+0x174/0x218
  bus_add_driver from driver_register+0x88/0x11c
  driver_register from do_one_initcall+0x64/0x380
  do_one_initcall from kernel_init_freeable+0x1c0/0x224
  kernel_init_freeable from kernel_init+0x18/0x12c
  kernel_init from ret_from_fork+0x14/0x2c
Exception stack(0xf082dfb0 to 0xf082dff8)
...

Let me know if You need anything more to test.


> drivers/net/ethernet/chelsio/cxgb4/cxgb4.h | 2 -
> .../ethernet/chelsio/cxgb4/cxgb4_thermal.c | 41 +----
> drivers/platform/x86/acerhdf.c | 73 +++-----
> drivers/thermal/armada_thermal.c | 39 ++---
> drivers/thermal/broadcom/bcm2835_thermal.c | 8 +-
> drivers/thermal/da9062-thermal.c | 52 +-----
> drivers/thermal/gov_bang_bang.c | 39 +++--
> drivers/thermal/gov_fair_share.c | 18 +-
> drivers/thermal/gov_power_allocator.c | 51 +++---
> drivers/thermal/gov_step_wise.c | 22 ++-
> drivers/thermal/hisi_thermal.c | 11 +-
> drivers/thermal/imx_thermal.c | 72 +++-----
> .../int340x_thermal/int340x_thermal_zone.c | 33 ++--
> .../int340x_thermal/int340x_thermal_zone.h | 4 +-
> .../processor_thermal_device.c | 10 +-
> drivers/thermal/intel/x86_pkg_temp_thermal.c | 120 +++++++------
> drivers/thermal/qcom/qcom-spmi-temp-alarm.c | 39 ++---
> drivers/thermal/rcar_gen3_thermal.c | 2 +-
> drivers/thermal/rcar_thermal.c | 53 +-----
> drivers/thermal/samsung/exynos_tmu.c | 57 +++----
> drivers/thermal/st/st_thermal.c | 47 +----
> drivers/thermal/tegra/soctherm.c | 33 ++--
> drivers/thermal/tegra/tegra30-tsensor.c | 17 +-
> drivers/thermal/thermal_core.c | 160 +++++++++++++++---
> drivers/thermal/thermal_core.h | 24 +--
> drivers/thermal/thermal_helpers.c | 28 +--
> drivers/thermal/thermal_netlink.c | 21 +--
> drivers/thermal/thermal_of.c | 116 -------------
> drivers/thermal/thermal_sysfs.c | 133 +++++----------
> drivers/thermal/ti-soc-thermal/ti-thermal.h | 15 --
> drivers/thermal/uniphier_thermal.c | 27 ++-
> include/linux/thermal.h | 10 ++
> 32 files changed, 559 insertions(+), 818 deletions(-)
>
Best regards

-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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