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Commit a602538e authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

srcu: Add DEBUG_OBJECTS_RCU_HEAD functionality 



This commit adds DEBUG_OBJECTS_RCU_HEAD checking to detect call_srcu()
counterparts to double-free bugs.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent d4efe6c5

kernel/rcu/srcutree.c

+18 −1
Original line number Diff line number Diff line
@@ -761,6 +761,13 @@ static bool srcu_might_be_idle(struct srcu_struct *sp) 
	return true; /* With reasonable probability, idle! */

}



/*

 * SRCU callback function to leak a callback.

 */

static void srcu_leak_callback(struct rcu_head *rhp)

{

}



/*

 * Enqueue an SRCU callback on the srcu_data structure associated with

 * the current CPU and the specified srcu_struct structure, initiating
@@ -799,6 +806,12 @@ void __call_srcu(struct srcu_struct *sp, struct rcu_head *rhp, 
	struct srcu_data *sdp;



	check_init_srcu_struct(sp);

	if (debug_rcu_head_queue(rhp)) {

		/* Probable double call_srcu(), so leak the callback. */

		WRITE_ONCE(rhp->func, srcu_leak_callback);

		WARN_ONCE(1, "call_srcu(): Leaked duplicate callback\n");

		return;

	}

	rhp->func = func;

	local_irq_save(flags);

	sdp = this_cpu_ptr(sp->sda);
@@ -973,9 +986,12 @@ void srcu_barrier(struct srcu_struct *sp) 
		spin_lock_irq(&sdp->lock);

		atomic_inc(&sp->srcu_barrier_cpu_cnt);

		sdp->srcu_barrier_head.func = srcu_barrier_cb;

		debug_rcu_head_queue(&sdp->srcu_barrier_head);

		if (!rcu_segcblist_entrain(&sdp->srcu_cblist,

					   &sdp->srcu_barrier_head, 0))

					   &sdp->srcu_barrier_head, 0)) {

			debug_rcu_head_unqueue(&sdp->srcu_barrier_head);

			atomic_dec(&sp->srcu_barrier_cpu_cnt);

		}

		spin_unlock_irq(&sdp->lock);

	}
@@ -1100,6 +1116,7 @@ static void srcu_invoke_callbacks(struct work_struct *work) 
	spin_unlock_irq(&sdp->lock);

	rhp = rcu_cblist_dequeue(&ready_cbs);

	for (; rhp != NULL; rhp = rcu_cblist_dequeue(&ready_cbs)) {

		debug_rcu_head_unqueue(rhp);

		local_bh_disable();

		rhp->func(rhp);

		local_bh_enable();