---
- branch: MAIN
  date: Sun Jan 16 20:24:34 UTC 2022
  files:
  - new: '1.24'
    old: '1.23'
    path: src/sys/dev/ic/tpm.c
    pathrev: src/sys/dev/ic/tpm.c@1.24
    type: modified
  id: 20220116T202434Z.d3a69872b57887702b6d7ee8ab2ade75f14f2f15
  log: |
    tpm(4): Fix suspend and rework I/O transaction lock.

    Use sc->sc_lock over individual I/O transactions, not open/close of
    the whole device.  This way there is a bounded time before the tpm is
    unbusied even if userland is getting at it, so userland can't hold up
    suspend indefinitely.  Of course, the tpm might be suspended and
    resumed in the middle of the user's session this way -- tough.

    This limits the response buffer to 1024 bytes -- which is already a
    bit hefty to have on the stack (but it's probably not very deep on
    the stack from userland so maybe not a big deal).  If it turns out we
    need more, we can use kmem to allocate a buffer on the heap, with the
    caveat that it might fail.  This is necessary so that suspend doesn't
    block indefinitely on uiomove in tpmread.
  module: src
  subject: 'CVS commit: src/sys/dev/ic'
  unixtime: '1642364674'
  user: riastradh