Commit de3f2671 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

srcu: Make Tiny SRCU poll_state_synchronize_srcu() more precise 



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: default avatarPaul E. McKenney <paulmck@kernel.org>
parent d66e4cf9

kernel/rcu/srcutiny.c

+2 −2
Original line number Diff line number Diff line
@@ -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);