drm/i915: Make i915_pipe_crc_read() oops proof

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Currently i915_pipe_crc_read() will drop pipe_crc->lock for the entire
duration of the copy_to_user() loop, which means it'll access
pipe_crc->entries without any protection. If another thread sneaks in
and frees pipe_crc->entries the code will oops.

Reorganize the code to hold the lock around everything except
copy_to_user(). After the copy the lock is reacquired and the the number
of available entries is rechecked.

Since this is a debug feature simplify the error handling a bit by
consuming the crc entry even if copy_to_user() would fail.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

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Ville Syrjälä 2014-12-09 21:28:32 +02:00 • committed by Daniel Vetter

parent 3cf54b34da

commit 9ad6d99f18

1 changed files with 22 additions and 17 deletions

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drivers/gpu/drm/i915/i915_debugfs.c

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