This commit applies the more-precise grace-period-state check used by
rcu_seq_done_exact() to poll_state_synchronize_srcu(). This is important
because Tiny SRCU uses a 16-bit counter, which can wrap quite quickly.
If counter wrap continues to be a problem, then expanding ->srcu_idx
and ->srcu_idx_max to 32 bits might be warranted.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
kernel/rcu/srcutiny.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c
index 92c002d654828..a2af24f214676 100644
--- a/kernel/rcu/srcutiny.c
+++ b/kernel/rcu/srcutiny.c
@@ -240,10 +240,10 @@ EXPORT_SYMBOL_GPL(start_poll_synchronize_srcu);
*/
bool poll_state_synchronize_srcu(struct srcu_struct *ssp, unsigned long cookie)
{
- bool ret = USHORT_CMP_GE(READ_ONCE(ssp->srcu_idx), cookie);
+ unsigned short cur_s = READ_ONCE(ssp->srcu_idx);
barrier();
- return ret;
+ return USHORT_CMP_GE(cur_s, cookie) || USHORT_CMP_LT(cur_s, cookie - 3);
}
EXPORT_SYMBOL_GPL(poll_state_synchronize_srcu);
--
2.31.1.189.g2e36527f23
