[GIT PULL] aio poll fixes for 5.16-rc5

[Eric Biggers <ebiggers@kernel.org>]

The following changes since commit 0fcfb00b28c0b7884635dacf38e46d60bf3d4eb1:

  Linux 5.16-rc4 (2021-12-05 14:08:22 -0800)

are available in the Git repository at:

  https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git tags/aio-poll-for-linus

for you to fetch changes up to 4b3749865374899e115aa8c48681709b086fe6d3:

  aio: Fix incorrect usage of eventfd_signal_allowed() (2021-12-09 10:52:55 -0800)

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Fix three bugs in aio poll, and one issue with POLLFREE more broadly:

  - aio poll didn't handle POLLFREE, causing a use-after-free.
  - aio poll could block while the file is ready.
  - aio poll called eventfd_signal() when it isn't allowed.
  - POLLFREE didn't handle multiple exclusive waiters correctly.

This has been tested with the libaio test suite, as well as with test
programs I wrote that reproduce the first two bugs.  I am sending this
pull request myself as no one seems to be maintaining this code.

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Eric Biggers (5):
      wait: add wake_up_pollfree()
      binder: use wake_up_pollfree()
      signalfd: use wake_up_pollfree()
      aio: keep poll requests on waitqueue until completed
      aio: fix use-after-free due to missing POLLFREE handling

Xie Yongji (1):
      aio: Fix incorrect usage of eventfd_signal_allowed()

 drivers/android/binder.c        |  21 ++---
 fs/aio.c                        | 186 ++++++++++++++++++++++++++++++++--------
 fs/signalfd.c                   |  12 +--
 include/linux/wait.h            |  26 ++++++
 include/uapi/asm-generic/poll.h |   2 +-
 kernel/sched/wait.c             |   7 ++
 6 files changed, 196 insertions(+), 58 deletions(-)