Commit ecc5e6b0 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Uladzislau Rezki (Sony)
Browse files

rcu: Add KCSAN exclusive-writer assertions for rdp->cpu_no_qs.b.exp 



The value of rdp->cpu_no_qs.b.exp may be changed only by the corresponding
CPU, and that CPU is not even allowed to race with itself, for example,
via interrupt handlers.  This commit therefore adds KCSAN exclusive-writer
assertions to check this constraint.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarUladzislau Rezki (Sony) <urezki@gmail.com>
parent 7a323371

kernel/rcu/tree_exp.h

+4 −0
Original line number Diff line number Diff line
@@ -262,6 +262,7 @@ static void rcu_report_exp_rdp(struct rcu_data *rdp) 


	raw_spin_lock_irqsave_rcu_node(rnp, flags);

	WRITE_ONCE(rdp->cpu_no_qs.b.exp, false);

	ASSERT_EXCLUSIVE_WRITER(rdp->cpu_no_qs.b.exp);

	rcu_report_exp_cpu_mult(rnp, flags, rdp->grpmask, true);

}
@@ -721,6 +722,7 @@ static void rcu_exp_sel_wait_wake(unsigned long s) 
/* Request an expedited quiescent state. */

static void rcu_exp_need_qs(void)

{

	ASSERT_EXCLUSIVE_WRITER_SCOPED(*this_cpu_ptr(&rcu_data.cpu_no_qs.b.exp));

	__this_cpu_write(rcu_data.cpu_no_qs.b.exp, true);

	/* Store .exp before .rcu_urgent_qs. */

	smp_store_release(this_cpu_ptr(&rcu_data.rcu_urgent_qs), true);
@@ -753,6 +755,7 @@ static void rcu_exp_handler(void *unused) 
	 * sync_sched_exp_online_cleanup() implementation being a no-op,

	 * so warn if this does happen.

	 */

	ASSERT_EXCLUSIVE_WRITER_SCOPED(rdp->cpu_no_qs.b.exp);

	if (WARN_ON_ONCE(!(READ_ONCE(rnp->expmask) & rdp->grpmask) ||

			 READ_ONCE(rdp->cpu_no_qs.b.exp)))

		return;
@@ -867,6 +870,7 @@ static void rcu_exp_handler(void *unused) 
	struct rcu_node *rnp = rdp->mynode;

	bool preempt_bh_enabled = !(preempt_count() & (PREEMPT_MASK | SOFTIRQ_MASK));



	ASSERT_EXCLUSIVE_WRITER_SCOPED(rdp->cpu_no_qs.b.exp);

	if (!(READ_ONCE(rnp->expmask) & rdp->grpmask) ||

	    __this_cpu_read(rcu_data.cpu_no_qs.b.exp))

		return;

kernel/rcu/tree_plugin.h

+1 −0
Original line number Diff line number Diff line
@@ -275,6 +275,7 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp) 
		rcu_report_exp_rdp(rdp);

	else

		WARN_ON_ONCE(rdp->cpu_no_qs.b.exp);

	ASSERT_EXCLUSIVE_WRITER_SCOPED(rdp->cpu_no_qs.b.exp);

}



/*