Mesa expects to be able to map the same buffer, without unmapping it.
This leads to problem on long-running program.
On the other hand, libdrm uses cpu_map_count as a refcount and expects
its value to decrease so it can unmap buffers.
The previoulsy proprosed fix (https://patchwork.freedesktop.org/patch/258005/)
stopped increased the counter when it went past INT_MAX.
This commit instead proposes to use a larger type to store cpu_map_count.
The outcome is the same: long running apps will not crash, only the
implementation differs.
Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/1423
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
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