Peter Fang f412d52546 dm: protect pthread_cond_wait() against spurious wakeups ...

Users of pthread_cond_wait() should take care of spurious wakeups and it
is usually used in conjunction with a predicate. Not doing so can result
in unintended behavior. For example:

virtio_net_tx_thread():
  entry -> pthread_cond_wait() -> spurious wakeup ->
  vq_clear_used_ring_flags() -> segfault (vq->used uninitialized)

tpm_crb_request_deliver():
  entry -> pthread_cond_wait() -> spurious wakeup ->
  swtpm_handle_request() called needlessly

virtio_rnd_get_entropy():
  entry -> pthread_cond_wait() -> spurious wakeup ->
  no avail ring processing ->
  virtio_rnd_notify() skips pthread_cond_signal() due to
  rnd->in_progress ->
  vq_endchains() called needlessly ->
  wait in pthread_cond_wait() indefinitely

Fix these uses of pthread_cond_wait() by using predicates.

The only use case without a clear predicate is the tx thread in
virtio-mei, because it works with two-dimensional linked lists.

v1 -> v2:
- fix bugs and comments
- reduce code redundancy

Tracked-On: #2763
Signed-off-by: Peter Fang <peter.fang@intel.com>
Reviewed-by: Shuo A Liu <shuo.a.liu@intel.com>

2019-04-04 00:27:10 +08:00

..

tpm_crb.c

dm: protect pthread_cond_wait() against spurious wakeups

2019-04-04 00:27:10 +08:00

tpm_emulator.c

dm: use strnlen to replace strlen

2018-12-25 18:40:04 +08:00

tpm_internal.h

DM: Support TPM2 CRB device virtualization

2018-11-29 09:19:16 +08:00

tpm.c

dm: use strncpy to replace strcpy

2018-12-25 18:40:04 +08:00