thermal/drivers/qcom: Fix lock inversion
authorJohan Hovold <johan+linaro@kernel.org>
Wed, 14 Dec 2022 13:16:17 +0000 (14:16 +0100)
committerDaniel Lezcano <daniel.lezcano@kernel.org>
Fri, 6 Jan 2023 13:14:48 +0000 (14:14 +0100)
commit59edcd91d852f88ef7d208029503f9b5310d0603
treed60f5336acb83a191e542d78bae9054577bd71eb
parentb0b5d063d66e85c24c32bf169fe4879bf08ea580
thermal/drivers/qcom: Fix lock inversion

The thermal-zone-device lock is held by core when setting trip points
and the driver takes its chip lock in the corresponding callback.

Fetching the thermal trip points using thermal_zone_get_trip() also
involves taking the thermal-zone-device lock, which means that the chip
lock can not be held when doing so.

Drop the chip lock temporarily during probe to avoid the lock inversion
that was detected by lockdep:

  ======================================================
  WARNING: possible circular locking dependency detected
  6.1.0-next-20221213 #122 Not tainted
  ------------------------------------------------------
  systemd-udevd/264 is trying to acquire lock:
  ffff741e444a0920 (&chip->lock){+.+.}-{3:3}, at: qpnp_tm_get_temp+0xb4/0x1b0 [qcom_spmi_temp_alarm]

  but task is already holding lock:
  ffff741e44341618 (&tz->lock){+.+.}-{3:3}, at: thermal_zone_device_update+0x2c/0x70

  which lock already depends on the new lock.

Fixes: 78c3e2429be8 ("thermal/drivers/qcom: Use generic thermal_zone_get_trip() function")
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20221214131617.2447-5-johan+linaro@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@kernel.org>
drivers/thermal/qcom/qcom-spmi-temp-alarm.c