This is a note to let you know that I've just added the patch titled
IB/qib: Correct reference counting in debugfs qp_stats
to the 3.16-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ib-qib-correct-reference-counting-in-debugfs-qp_stats.patch
and it can be found in the queue-3.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 85cbb7c728bf39c45a9789b88c9471c0d7a58b0e Mon Sep 17 00:00:00 2001
From: Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx>
Date: Fri, 19 Sep 2014 08:32:19 -0400
Subject: IB/qib: Correct reference counting in debugfs qp_stats
From: Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx>
Signed-off-by: Roland Dreier <roland@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
}
Patches currently in stable-queue which might be from mike.marciniszyn@xxxxxxxxx are
queue-3.16/ib-qib-correct-reference-counting-in-debugfs-qp_stats.patch
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