---
- branch: MAIN
  date: Fri Jan 14 22:25:49 UTC 2022
  files:
  - new: '1.21'
    old: '1.20'
    path: src/sys/dev/i2c/ihidev.c
    pathrev: src/sys/dev/i2c/ihidev.c@1.21
    type: modified
  - new: '1.6'
    old: '1.5'
    path: src/sys/dev/i2c/ihidev.h
    pathrev: src/sys/dev/i2c/ihidev.h@1.6
    type: modified
  id: 20220114T222549Z.74bf18f9110c9a3fcc42a60187aacd36b0a01061
  log: |
    ihidev(4): Fix locking and interrupt handler.

    - Can't run iic_exec in softint because it does cv_wait, at least on
      some i2c controllers -- defer to workqueue instead.

    - Fix violations of locking rules:
      . Do not take a lock at higher IPL than it is defined at!
      . Do not sleep under a lock!
      . Definitely do not sleep under a spin lock!
      In this case, sc_intr_lock was defined at IPL_VM but used at IPL_TTY,
      and i2c transactions -- possibly causing sleep for cv_wait -- were
      issued under it.

      But in this case, the interrupt handler needs only a single bit to
      mark whether the work is pending, so just use atomic_swap for that.

    - Use an adaptive lock (IPL_NONE) for i2c transactions.

    - Detach children, and do so before freeing anything.
  module: src
  subject: 'CVS commit: src/sys/dev/i2c'
  unixtime: '1642199149'
  user: riastradh