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Message-ID: <5525F3B3.2000208@roeck-us.net>
Date: Wed, 08 Apr 2015 20:36:19 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Nishanth Menon <nm@...com>, Jean Delvare <jdelvare@...e.de>
CC: linux-kernel@...r.kernel.org, lm-sensors@...sensors.org,
linux-omap@...r.kernel.org, Eduardo Valentin <edubezval@...il.com>
Subject: Re: [PATCH] (gpio-fan): Move the thermal registration after registration
is complete
On 04/08/2015 04:23 PM, Nishanth Menon wrote:
> Thermal framework may already be ready and cooling policies might
> already be functional when we are attempting to register gpio fan as
> a cooling device. This can be reproduced by changing probe order in
> which registration of various modules are done in a system. In such
> a case, kernel generates an oops since the data structures are not
> completely populated with the wrong assumption that thermal framework
> is not yet ready. Fix this by reordering the thermal framework
> registration to occur after hwmon registration of the fan is complete.
>
> Example kernel oops:
> [ 149.005828] Unable to handle kernel NULL pointer dereference at virtual address 0000008c
> [ 149.014369] pgd = ecf48000
> [ 149.017204] [0000008c] *pgd=ac065831, *pte=00000000, *ppte=00000000
> [ 149.023820] Internal error: Oops: 17 [#1] SMP ARM
> [ 149.028745] Modules linked in: gpio_fan(+) cpufreq_dt ipv6 evdev leds_gpio led_class omap_wdt phy_omap_usb2 rtc_palmas palmas_pwrbutton tmp102 ti_soc_thermal dwc3_omap thermal_sys extcon rtc_omap rtc_ds1307 hwmon
> [ 149.048629] CPU: 1 PID: 1183 Comm: modprobe Not tainted 4.0.0-rc7-next-20150407-00002-g7a82da074c99 #3
> [ 149.058383] Hardware name: Generic DRA74X (Flattened Device Tree)
> [ 149.064763] task: edec1240 ti: ec0e0000 task.ti: ec0e0000
> [ 149.070421] PC is at dev_driver_string+0x0/0x38
> [ 149.075165] LR is at __dev_printk+0x24/0x70
> [ 149.079540] pc : [<c03d6cd0>] lr : [<c03d72c4>] psr: 20000013
> [ 149.079540] sp : ec0e1c28 ip : edec1240 fp : 00000000
> [ 149.091568] r10: edf3eee0 r9 : 00000000 r8 : ffffffff
> [ 149.097040] r7 : edf3eea0 r6 : 00000034 r5 : 00000010 r4 : ec0e1c44
> [ 149.103871] r3 : ec0e1c4c r2 : ec0e1c44 r1 : c079d800 r0 : 00000010
> [ 149.110709] Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
> [ 149.118182] Control: 10c5387d Table: acf4806a DAC: 00000015
> [ 149.124198] Process modprobe (pid: 1183, stack limit = 0xec0e0218)
> [ 149.130673] Stack: (0xec0e1c28 to 0xec0e2000)
> [ 149.135235] 1c20: 60000013 c05e2ae0 00000000 edf3ec00 ec934a10 c03d73d4
> ...
> [ 149.392230] 1fe0: befe1888 befe1878 00019418 b6ea08f0 80000010 00000003 00000000 00000000
> [ 149.400798] [<c03d6cd0>] (dev_driver_string) from [<c03d72c4>] (__dev_printk+0x24/0x70)
> [ 149.409193] [<c03d72c4>] (__dev_printk) from [<c03d73d4>] (dev_warn+0x34/0x48)
> [ 149.416767] [<c03d73d4>] (dev_warn) from [<bf0f54fc>] (get_fan_speed_index+0x94/0xa4 [gpio_fan])
> [ 149.425980] [<bf0f54fc>] (get_fan_speed_index [gpio_fan]) from [<bf0f5524>] (gpio_fan_get_cur_state+0x18/0x30 [gpio_fan])
> [ 149.437476] [<bf0f5524>] (gpio_fan_get_cur_state [gpio_fan]) from [<bf02767c>] (thermal_zone_trip_update+0xe8/0x2a4 [thermal_sys])
> [ 149.449794] [<bf02767c>] (thermal_zone_trip_update [thermal_sys]) from [<bf027844>] (step_wise_throttle+0xc/0x74 [thermal_sys])
> [ 149.461832] [<bf027844>] (step_wise_throttle [thermal_sys]) from [<bf024ff4>] (handle_thermal_trip+0x5c/0x188 [thermal_sys])
> [ 149.473603] [<bf024ff4>] (handle_thermal_trip [thermal_sys]) from [<bf0256c4>] (thermal_zone_device_update+0x94/0x108 [thermal_sys])
> [ 149.486104] [<bf0256c4>] (thermal_zone_device_update [thermal_sys]) from [<bf026470>] (__thermal_cooling_device_register+0x2e8/0x374 [thermal_sys])
> [ 149.499956] [<bf026470>] (__thermal_cooling_device_register [thermal_sys]) from [<bf0f58e4>] (gpio_fan_probe+0x350/0x4d0 [gpio_fan])
> [ 149.512438] [<bf0f58e4>] (gpio_fan_probe [gpio_fan]) from [<c03db8a0>] (platform_drv_probe+0x48/0x98)
> [ 149.522109] [<c03db8a0>] (platform_drv_probe) from [<c03da30c>] (driver_probe_device+0x1b0/0x26c)
> [ 149.531399] [<c03da30c>] (driver_probe_device) from [<c03da45c>] (__driver_attach+0x94/0x98)
> [ 149.540238] [<c03da45c>] (__driver_attach) from [<c03d8bb0>] (bus_for_each_dev+0x54/0x88)
> [ 149.548814] [<c03d8bb0>] (bus_for_each_dev) from [<c03d9a34>] (bus_add_driver+0xdc/0x1d4)
> [ 149.557381] [<c03d9a34>] (bus_add_driver) from [<c03dac30>] (driver_register+0x78/0xf4)
> [ 149.565765] [<c03dac30>] (driver_register) from [<c0009784>] (do_one_initcall+0x80/0x1d8)
> [ 149.574340] [<c0009784>] (do_one_initcall) from [<c00c2278>] (do_init_module+0x5c/0x1b8)
> [ 149.582833] [<c00c2278>] (do_init_module) from [<c00c3bbc>] (load_module+0x1720/0x1dcc)
> [ 149.591212] [<c00c3bbc>] (load_module) from [<c00c43d0>] (SyS_finit_module+0x68/0x6c)
> [ 149.599418] [<c00c43d0>] (SyS_finit_module) from [<c000f3c0>] (ret_fast_syscall+0x0/0x4c)
> [ 149.607994] Code: 15830000 e1a00006 e28dd008 e8bd8070 (e590307c)
>
> Cc: Eduardo Valentin <edubezval@...il.com>
>
> Fixes: b5cf88e46bad ("(gpio-fan): Add thermal control hooks")
> Signed-off-by: Nishanth Menon <nm@...com>
> ---
>
Applied to -next.
Thanks,
Guenter
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