sna: Preallocate pwrite scratch buffer for old fashioned cursor updates

We need to avoid all allocations within the signal handlers, so
preallocate the transfer buffer.

References: https://bugs.freedesktop.org/show_bug.cgi?id=77975
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/sna/sna.h b/src/sna/sna.h
index bd6eb491..fc73f7e6 100644
--- a/src/sna/sna.h
+++ b/src/sna/sna.h
@@ -297,6 +297,8 @@ struct sna {
 
 		unsigned max_size;
 		bool use_gtt;
+
+		void *scratch;
 	} cursor;
 
 	struct sna_dri {