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Commit 85cbb7c7 authored by Mike Marciniszyn's avatar Mike Marciniszyn Committed by Roland Dreier
Browse files

IB/qib: Correct reference counting in debugfs qp_stats 



This particular reference count is not needed with the rcu protection,
and the current code leaks a reference count, causing a hang in
qib_qp_destroy().

Cc: <stable@vger.kernel.org>
Reviewed-by: default avatarDennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: default avatarMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
parent f5c4984e

drivers/infiniband/hw/qib/qib_debugfs.c

+2 −1
Original line number Diff line number Diff line
@@ -193,6 +193,7 @@ static void *_qp_stats_seq_start(struct seq_file *s, loff_t *pos) 
	struct qib_qp_iter *iter;

	loff_t n = *pos;



	rcu_read_lock();

	iter = qib_qp_iter_init(s->private);

	if (!iter)

		return NULL;
@@ -224,7 +225,7 @@ static void *_qp_stats_seq_next(struct seq_file *s, void *iter_ptr, 


static void _qp_stats_seq_stop(struct seq_file *s, void *iter_ptr)

{

	/* nothing for now */

	rcu_read_unlock();

}



static int _qp_stats_seq_show(struct seq_file *s, void *iter_ptr)

drivers/infiniband/hw/qib/qib_qp.c

+0 −8
Original line number Diff line number Diff line
@@ -1325,7 +1325,6 @@ int qib_qp_iter_next(struct qib_qp_iter *iter) 
	struct qib_qp *pqp = iter->qp;

	struct qib_qp *qp;



	rcu_read_lock();

	for (; n < dev->qp_table_size; n++) {

		if (pqp)

			qp = rcu_dereference(pqp->next);
@@ -1333,18 +1332,11 @@ int qib_qp_iter_next(struct qib_qp_iter *iter) 
			qp = rcu_dereference(dev->qp_table[n]);

		pqp = qp;

		if (qp) {

			if (iter->qp)

				atomic_dec(&iter->qp->refcount);

			atomic_inc(&qp->refcount);

			rcu_read_unlock();

			iter->qp = qp;

			iter->n = n;

			return 0;

		}

	}

	rcu_read_unlock();

	if (iter->qp)

		atomic_dec(&iter->qp->refcount);

	return ret;

}