The last_rw map is initialized with a value of 0 but later assigned the
value args.sector + args.nr_sector, which has type sector_t = u64.
bpftrace complains about the type mismatch between int64 and uint64:
trace/seq_io.bt:18:3-59: ERROR: Type mismatch for @last_rw: trying to assign value of type 'uint64' when map already contains a value of type 'int64'
        @last_rw[$dev, str($2)] = (args.sector + args.nr_sector);

Cast the initial value to uint64 so bpftrace will load the program.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
---
 tools/testing/selftests/ublk/trace/seq_io.bt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/ublk/trace/seq_io.bt b/tools/testing/selftests/ublk/trace/seq_io.bt
index 272ac54c9d5f..507a3ca05abf 100644
--- a/tools/testing/selftests/ublk/trace/seq_io.bt
+++ b/tools/testing/selftests/ublk/trace/seq_io.bt
@@ -2,11 +2,11 @@
 	$1: 	dev_t
 	$2: 	RWBS
 	$3:     strlen($2)
 */
 BEGIN {
-	@last_rw[$1, str($2)] = 0;
+	@last_rw[$1, str($2)] = (uint64)0;
 }
 tracepoint:block:block_rq_complete
 {
 	$dev = $1;
 	if ((int64)args.dev == $1 && !strncmp(args.rwbs, str($2), $3)) {
-- 
2.45.2