It is enough to have three values of rcu_gp.ctr, 00 for INACTIVE,
01 or 11 for ACTIVE. So it is possible to replace add operation
with xor operation when changing rcu_gp.ctr value.

Signed-off-by: yaowenbin <[email protected]>
---
 src/urcu-qsbr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/urcu-qsbr.c b/src/urcu-qsbr.c
index 3709412..46135f9 100644
--- a/src/urcu-qsbr.c
+++ b/src/urcu-qsbr.c
@@ -391,7 +391,7 @@ void urcu_qsbr_synchronize_rcu(void)
                goto out;

        /* Increment current G.P. */
-       CMM_STORE_SHARED(urcu_qsbr_gp.ctr, urcu_qsbr_gp.ctr + URCU_QSBR_GP_CTR);
+       CMM_STORE_SHARED(urcu_qsbr_gp.ctr, urcu_qsbr_gp.ctr ^ URCU_QSBR_GP_CTR);

        /*
         * Must commit urcu_qsbr_gp.ctr update to memory before waiting for
-- 
2.27.0
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