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IB/hfi1,IB/qib: Fix qp_stats sleep with rcu read lock held

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The qp init function does a kzalloc() while holding the RCU
lock that encounters the following warning with a debug kernel
when a cat of the qp_stats is done:

[  231.723948] rcu_scheduler_active = 1, debug_locks = 0
[  231.731939] 3 locks held by cat/11355:
[  231.736492]  #0:  (debugfs_srcu){......}, at: [<ffffffff813001a5>] debugfs_use_file_start+0x5/0x90
[  231.746955]  #1:  (&p->lock){+.+.+.}, at: [<ffffffff81289a6c>] seq_read+0x4c/0x3c0
[  231.755873]  #2:  (rcu_read_lock){......}, at: [<ffffffffa0a0c535>] _qp_stats_seq_start+0x5/0xd0 [hfi1]
[  231.766862]

The init functions do an implicit next which requires the rcu read lock
before the kzalloc().

Fix for both drivers is to change the scope of the init function to only
do the allocation and the initialization of the just allocated iter.

The implict next is moved back into the respective start functions to fix
the issue.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
CC: <stable@vger.kernel.org> # 4.6.x-
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
This commit is contained in:
Mike Marciniszyn 2016-08-12 11:17:37 -04:00 committed by Doug Ledford
parent abb658ef05
commit c62fb260a8
4 changed files with 18 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/infiniband/hw/hfi1/debugfs.c
View File

@ -223,28 +223,32 @@ DEBUGFS_SEQ_FILE_OPEN(ctx_stats)
DEBUGFS_FILE_OPS(ctx_stats);
static void *_qp_stats_seq_start(struct seq_file *s, loff_t *pos)
__acquires(RCU)
__acquires(RCU)
{
struct qp_iter *iter;
loff_t n = *pos;
rcu_read_lock();
iter = qp_iter_init(s->private);
/* stop calls rcu_read_unlock */
rcu_read_lock();
if (!iter)
return NULL;
while (n--) {
do {
if (qp_iter_next(iter)) {
kfree(iter);
return NULL;
}
}
} while (n--);
return iter;
}
static void *_qp_stats_seq_next(struct seq_file *s, void *iter_ptr,
loff_t *pos)
__must_hold(RCU)
{
struct qp_iter *iter = iter_ptr;
@ -259,7 +263,7 @@ 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)
__releases(RCU)
__releases(RCU)
{
rcu_read_unlock();
}

4
drivers/infiniband/hw/hfi1/qp.c
View File

@ -656,10 +656,6 @@ struct qp_iter *qp_iter_init(struct hfi1_ibdev *dev)
iter->dev = dev;
iter->specials = dev->rdi.ibdev.phys_port_cnt * 2;
if (qp_iter_next(iter)) {
kfree(iter);
return NULL;
}
return iter;
}

12
drivers/infiniband/hw/qib/qib_debugfs.c
View File

@ -189,27 +189,32 @@ static int _ctx_stats_seq_show(struct seq_file *s, void *v)
DEBUGFS_FILE(ctx_stats)
static void *_qp_stats_seq_start(struct seq_file *s, loff_t *pos)
__acquires(RCU)
{
struct qib_qp_iter *iter;
loff_t n = *pos;
rcu_read_lock();
iter = qib_qp_iter_init(s->private);
/* stop calls rcu_read_unlock */
rcu_read_lock();
if (!iter)
return NULL;
while (n--) {
do {
if (qib_qp_iter_next(iter)) {
kfree(iter);
return NULL;
}
}
} while (n--);
return iter;
}
static void *_qp_stats_seq_next(struct seq_file *s, void *iter_ptr,
loff_t *pos)
__must_hold(RCU)
{
struct qib_qp_iter *iter = iter_ptr;
@ -224,6 +229,7 @@ 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)
__releases(RCU)
{
rcu_read_unlock();
}

4
drivers/infiniband/hw/qib/qib_qp.c
View File

@ -573,10 +573,6 @@ struct qib_qp_iter *qib_qp_iter_init(struct qib_ibdev *dev)
return NULL;
iter->dev = dev;
if (qib_qp_iter_next(iter)) {
kfree(iter);
return NULL;
}
return iter;
}