From: Jon Hunter <jonathanh@nvidia.com>
To: Guenter Roeck <linux@roeck-us.net>,
Dmitry Osipenko <digetx@gmail.com>,
Jean Delvare <jdelvare@suse.com>
Cc: linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org,
linux-tegra@vger.kernel.org
Subject: Re: [PATCH v3 2/4] hwmon: (lm90) Use hwmon_notify_event()
Date: Mon, 21 Feb 2022 15:49:16 +0000 [thread overview]
Message-ID: <84ddad27-eb22-0ba6-594f-2fc6d098dc2a@nvidia.com> (raw)
In-Reply-To: <2aae3bac-c9b3-ab47-aae4-a3c7b6fb4bb5@roeck-us.net>
On 21/02/2022 15:43, Guenter Roeck wrote:
...
>> 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.
>>
> As mentioned separately, this is not the problem.
Yes I can see that now.
> I think the problem may be that this is not a devicetree system
> (or the lm90 devide does not have a devicetree node), but thermal
> notification currently only works in such systems because the hwmon
> subsystem uses the devicetree registration method. At the same time,
> CONFIG_THERMAL_OF is obviously enabled. Unfortunately, the hwmon code
> does not bail out in that situation due to another bug.
The platform I see this on does use device-tree and it does have a node
for the ti,tmp451 device which uses the lm90 device. This platform uses
the device-tree source
arch/arm64/boot/dts/nvidia/tegra194-p2972-0000.dts and the tmp451 node
is in arch/arm64/boot/dts/nvidia/tegra194-p2888.dtsi.
Cheers
Jon
--
nvpublic
next prev parent reply other threads:[~2022-02-21 15:49 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-18 21:54 [PATCH v3 0/4] HWMON LM90 interrupt fixes and improvements Dmitry Osipenko
2021-06-18 21:54 ` [PATCH v3 1/4] hwmon: (lm90) Don't override interrupt trigger type Dmitry Osipenko
2021-06-18 21:54 ` [PATCH v3 2/4] hwmon: (lm90) Use hwmon_notify_event() Dmitry Osipenko
2022-02-21 12:01 ` Jon Hunter
2022-02-21 12:36 ` Dmitry Osipenko
2022-02-21 12:56 ` Jon Hunter
2022-02-21 12:59 ` Dmitry Osipenko
2022-02-21 13:50 ` Jon Hunter
2022-02-21 13:59 ` Dmitry Osipenko
2022-02-21 15:25 ` Guenter Roeck
2022-02-21 15:43 ` Guenter Roeck
2022-02-21 15:49 ` Jon Hunter [this message]
2022-02-21 16:02 ` Guenter Roeck
2022-02-21 16:13 ` Dmitry Osipenko
2022-02-21 16:16 ` Jon Hunter
2022-02-21 16:20 ` Dmitry Osipenko
2022-02-21 16:42 ` Guenter Roeck
2022-02-21 16:22 ` Jon Hunter
2022-02-21 18:38 ` Guenter Roeck
2022-02-21 16:23 ` Guenter Roeck
2021-06-18 21:54 ` [PATCH v3 3/4] hwmon: (lm90) Unmask hardware interrupt Dmitry Osipenko
2021-06-18 21:54 ` [PATCH v3 4/4] hwmon: (lm90) Disable interrupt on suspend Dmitry Osipenko
2021-06-19 11:10 ` [PATCH v3 0/4] HWMON LM90 interrupt fixes and improvements Guenter Roeck
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