Messages in this thread | | | Date | Mon, 21 Feb 2022 12:01:10 +0000 | Subject | Re: [PATCH v3 2/4] hwmon: (lm90) Use hwmon_notify_event() | From | Jon Hunter <> |
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Hi Dmitry,
On 18/06/2021 22:54, Dmitry Osipenko wrote: > Use hwmon_notify_event() to notify userspace and thermal core about > temperature changes. > > Suggested-by: Guenter Roeck <linux@roeck-us.net> > Signed-off-by: Dmitry Osipenko <digetx@gmail.com> > --- > drivers/hwmon/lm90.c | 44 +++++++++++++++++++++++++++++++++----------- > 1 file changed, 33 insertions(+), 11 deletions(-) > > diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c > index 2e057fad05b4..e7b678a40b39 100644 > --- a/drivers/hwmon/lm90.c > +++ b/drivers/hwmon/lm90.c > @@ -465,6 +465,7 @@ enum lm90_temp11_reg_index { > > struct lm90_data { > struct i2c_client *client; > + struct device *hwmon_dev; > u32 channel_config[4]; > struct hwmon_channel_info temp_info; > const struct hwmon_channel_info *info[3]; > @@ -1731,22 +1732,41 @@ static bool lm90_is_tripped(struct i2c_client *client, u16 *status) > > if ((st & (LM90_STATUS_LLOW | LM90_STATUS_LHIGH | LM90_STATUS_LTHRM)) || > (st2 & MAX6696_STATUS2_LOT2)) > - dev_warn(&client->dev, > - "temp%d out of range, please check!\n", 1); > + dev_dbg(&client->dev, > + "temp%d out of range, please check!\n", 1); > if ((st & (LM90_STATUS_RLOW | LM90_STATUS_RHIGH | LM90_STATUS_RTHRM)) || > (st2 & MAX6696_STATUS2_ROT2)) > - dev_warn(&client->dev, > - "temp%d out of range, please check!\n", 2); > + dev_dbg(&client->dev, > + "temp%d out of range, please check!\n", 2); > if (st & LM90_STATUS_ROPEN) > - dev_warn(&client->dev, > - "temp%d diode open, please check!\n", 2); > + dev_dbg(&client->dev, > + "temp%d diode open, please check!\n", 2); > if (st2 & (MAX6696_STATUS2_R2LOW | MAX6696_STATUS2_R2HIGH | > MAX6696_STATUS2_R2THRM | MAX6696_STATUS2_R2OT2)) > - dev_warn(&client->dev, > - "temp%d out of range, please check!\n", 3); > + dev_dbg(&client->dev, > + "temp%d out of range, please check!\n", 3); > if (st2 & MAX6696_STATUS2_R2OPEN) > - dev_warn(&client->dev, > - "temp%d diode open, please check!\n", 3); > + dev_dbg(&client->dev, > + "temp%d diode open, please check!\n", 3); > + > + if (st & LM90_STATUS_LLOW) > + hwmon_notify_event(data->hwmon_dev, hwmon_temp, > + hwmon_temp_min, 0); > + if (st & LM90_STATUS_RLOW) > + hwmon_notify_event(data->hwmon_dev, hwmon_temp, > + hwmon_temp_min, 1); > + if (st2 & MAX6696_STATUS2_R2LOW) > + hwmon_notify_event(data->hwmon_dev, hwmon_temp, > + hwmon_temp_min, 2); > + if (st & LM90_STATUS_LHIGH) > + hwmon_notify_event(data->hwmon_dev, hwmon_temp, > + hwmon_temp_max, 0); > + if (st & LM90_STATUS_RHIGH) > + hwmon_notify_event(data->hwmon_dev, hwmon_temp, > + hwmon_temp_max, 1); > + if (st2 & MAX6696_STATUS2_R2HIGH) > + hwmon_notify_event(data->hwmon_dev, hwmon_temp, > + hwmon_temp_max, 2);
We observed a random null pointer deference crash somewhere in the thermal core (crash log below is not very helpful) when calling mutex_lock(). It looks like we get an interrupt when this crash happens.
Looking at the lm90 driver, per the above, I now see we are calling hwmon_notify_event() from the lm90 interrupt handler. Looking at hwmon_notify_event() I see that ...
hwmon_notify_event() --> hwmon_thermal_notify() --> thermal_zone_device_update() --> update_temperature() --> mutex_lock()
So although I don't completely understand the crash, it does seem that we should not be calling hwmon_notify_event() from the interrupt handler.
BTW I have not reproduced this myself yet, so I have just been reviewing the code to try and understand this.
Jon
[ 7465.595066] Unable to handle kernel NULL pointer dereference at virtual address 00000000000003cd [ 7465.596619] Mem abort info: [ 7465.597854] ESR = 0x96000021 [ 7465.599097] EC = 0x25: DABT (current EL), IL = 32 bits [ 7465.600338] SET = 0, FnV = 0 [ 7465.601526] EA = 0, S1PTW = 0 [ 7465.602705] FSC = 0x21: alignment fault [ 7465.603885] Data abort info: [ 7465.605017] ISV = 0, ISS = 0x00000021 [ 7465.606171] CM = 0, WnR = 0 [ 7465.607301] user pgtable: 64k pages, 48-bit VAs, pgdp=00000001041f1800 [ 7465.608490] [00000000000003cd] pgd=0000000000000000, p4d=0000000000000000, pud=0000000000000000 [ 7465.609814] Internal error: Oops: 96000021 [#1] PREEMPT SMP [ 7465.610991] Modules linked in: bridge stp llc snd_soc_tegra210_admaif snd_soc_tegra_pcm snd_soc_tegra210_mixer snd_soc_tegra210_mvc snd_soc_tegra210_i2s snd_soc_tegra210_dmic sn d_soc_tegra210_adx snd_soc_tegra210_sfc snd_soc_tegra210_amx snd_soc_tegra210_ahub tegra210_adma snd_soc_rt5659 snd_soc_rl6231 pwm_tegra tegra_aconnect snd_hda_codec_hdmi rfkill snd_hda_tegra snd_hda_codec at24 phy_tegra194_p2u snd_hda_core lm90 snd_soc_tegra_audio_graph_card tegra_bpmp_thermal snd_soc_audio_graph_card snd_soc_simple_card_utils pwm_fan crct10dif_ce pcie_tegra194 cec drm_kms_helper drm ip_tables x_tables ipv6 [ 7465.632232] CPU: 2 PID: 433 Comm: irq/140-lm90 Tainted: G O 5.16.0-tegra-g9d109504d83a #1 [ 7465.636285] Hardware name: Unknown NVIDIA Jetson AGX Xavier Developer Kit/NVIDIA Jetson AGX Xavier Developer Kit, BIOS v1.1.2-901d3c52 02/07/2022 [ 7465.650457] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 7465.656210] pc : mutex_lock+0x18/0x60 [ 7465.660134] lr : thermal_zone_device_update+0x40/0x2e0 [ 7465.665117] sp : ffff800014c4fc60 [ 7465.668781] x29: ffff800014c4fc60 x28: ffff365ee3f6e000 x27: ffffdde218426790 [ 7465.675882] x26: ffff365ee3f6e000 x25: 0000000000000000 x24: ffff365ee3f6e000 [ 7465.683485] x23: ffffdde218426870 x22: ffff365ee3f6e000 x21: 00000000000003cd [ 7465.690816] x20: ffff365ee8bf3308 x19: ffffffffffffffed x18: 0000000000000000 [ 7465.697982] x17: ffffdde21842689c x16: ffffdde1cb7a0b7c x15: 0000000000000040 [ 7465.705320] x14: ffffdde21a4889a0 x13: 0000000000000228 x12: 0000000000000000 [ 7465.712493] x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 [ 7465.719580] x8 : 0000000001120000 x7 : 0000000000000001 x6 : 0000000000000000 [ 7465.727099] x5 : 0068000878e20f07 x4 : 0000000000000000 x3 : 00000000000003cd [ 7465.734348] x2 : ffff365ee3f6e000 x1 : 0000000000000000 x0 : 00000000000003cd [ 7465.741347] Call trace: [ 7465.744207] mutex_lock+0x18/0x60 [ 7465.747427] hwmon_notify_event+0xfc/0x110 [ 7465.751358] 0xffffdde1cb7a0a90 [ 7465.754574] 0xffffdde1cb7a0b7c [ 7465.757705] irq_thread_fn+0x2c/0xa0 [ 7465.760937] irq_thread+0x134/0x240 [ 7465.764850] kthread+0x178/0x190 [ 7465.768083] ret_from_fork+0x10/0x20 [ 7465.771748] Code: d503201f d503201f d2800001 aa0103e4 (c8e47c02) [ 7465.777865] ---[ end trace f0b3723991411538 ]---
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