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Add gk20a_channel_from_id() to retrieve a channel, given a raw channel
ID, with a reference taken (or NULL if the channel was dead). This makes
it harder to mistakenly use a channel that's dead and thus uncovers bugs
sooner. Convert code to use the new lookup when applicable; work remains
to convert complex uses where a ref should have been taken but hasn't.
The channel ID is also validated against FIFO_INVAL_CHANNEL_ID; NULL is
returned for such IDs. This is often useful and does not hurt when
unnecessary.
However, this does not prevent the case where a channel would be closed
and reopened again when someone would hold a stale channel number. In
all such conditions the caller should hold a reference already.
The only conditions where a channel can be safely looked up by an id and
used without taking a ref are when initializing or deinitializing the
list of channels.
Jira NVGPU-1460
Change-Id: I0a30968d17c1e0784d315a676bbe69c03a73481c
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1955400
Signed-off-by: Debarshi Dutta <ddutta@nvidia.com>
(cherry picked from commit 7df3d58750
in dev-kernel)
Reviewed-on: https://git-master.nvidia.com/r/2008515
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>