[0/2] Fix crash due to open pmu events during unbind

Message

Umesh Nerlige Ramappa Feb. 13, 2024, 6:03 p.m. UTC

Once a user opens an fd for a perf event, if the driver undergoes a
function level reset (FLR), the resources are not cleaned up as
expected. For this discussion FLR is defined as a PCI unbind followed by
a bind. perf_pmu_unregister() would cleanup everything, but when the
user closes the perf fd much later, perf_release() is called and we
encounter null pointer dereferences and/or list corruption in that path
which require a reboot to recover.

The only approach that worked to resolve this was to close the file
associated with the event such that the relevant cleanup happens w.r.t.
the open file. To do so, use the event->owner task and find the file
relevant to the event and close it. This relies on the
file->private_data matching the event object.

Test-with: [e-mail]
Signed-off-by: Umesh Nerlige Ramappa <[e-mail]>

Umesh Nerlige Ramappa (2):
  i915/pmu: Add pmu_teardown helper
  i915/pmu: Cleanup pending events on unbind

 drivers/gpu/drm/i915/i915_pmu.c | 192 ++++++++++++++++++++++++--------
 drivers/gpu/drm/i915/i915_pmu.h |  15 +++
 2 files changed, 161 insertions(+), 46 deletions(-)