| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.16 297/357] IB/qib: Correct reference counting in debugfs qp_stats | Date | Fri, 3 Oct 2014 14:31:23 -0700 |
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3.16-stable review patch. If anyone has any objections, please let me know.
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From: Mike Marciniszyn <mike.marciniszyn@intel.com>
commit 85cbb7c728bf39c45a9789b88c9471c0d7a58b0e upstream.
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().
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com> Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com> Signed-off-by: Roland Dreier <roland@purestorage.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/infiniband/hw/qib/qib_debugfs.c | 3 ++- drivers/infiniband/hw/qib/qib_qp.c | 8 -------- 2 files changed, 2 insertions(+), 9 deletions(-)
--- a/drivers/infiniband/hw/qib/qib_debugfs.c +++ b/drivers/infiniband/hw/qib/qib_debugfs.c @@ -193,6 +193,7 @@ static void *_qp_stats_seq_start(struct 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 s 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) --- a/drivers/infiniband/hw/qib/qib_qp.c +++ b/drivers/infiniband/hw/qib/qib_qp.c @@ -1325,7 +1325,6 @@ int qib_qp_iter_next(struct qib_qp_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 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; }
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