Commit c62fb260 authored by Mike Marciniszyn's avatar Mike Marciniszyn Committed by Doug Ledford

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

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: default avatarIra Weiny <ira.weiny@intel.com>
Signed-off-by: default avatarMike Marciniszyn <mike.marciniszyn@intel.com>
CC: <stable@vger.kernel.org> # 4.6.x-
Reviewed-by: default avatarLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
parent abb658ef
...@@ -223,28 +223,32 @@ DEBUGFS_SEQ_FILE_OPEN(ctx_stats) ...@@ -223,28 +223,32 @@ DEBUGFS_SEQ_FILE_OPEN(ctx_stats)
DEBUGFS_FILE_OPS(ctx_stats); DEBUGFS_FILE_OPS(ctx_stats);
static void *_qp_stats_seq_start(struct seq_file *s, loff_t *pos) static void *_qp_stats_seq_start(struct seq_file *s, loff_t *pos)
__acquires(RCU) __acquires(RCU)
{ {
struct qp_iter *iter; struct qp_iter *iter;
loff_t n = *pos; loff_t n = *pos;
rcu_read_lock();
iter = qp_iter_init(s->private); iter = qp_iter_init(s->private);
/* stop calls rcu_read_unlock */
rcu_read_lock();
if (!iter) if (!iter)
return NULL; return NULL;
while (n--) { do {
if (qp_iter_next(iter)) { if (qp_iter_next(iter)) {
kfree(iter); kfree(iter);
return NULL; return NULL;
} }
} } while (n--);
return iter; return iter;
} }
static void *_qp_stats_seq_next(struct seq_file *s, void *iter_ptr, static void *_qp_stats_seq_next(struct seq_file *s, void *iter_ptr,
loff_t *pos) loff_t *pos)
__must_hold(RCU)
{ {
struct qp_iter *iter = iter_ptr; struct qp_iter *iter = iter_ptr;
...@@ -259,7 +263,7 @@ static void *_qp_stats_seq_next(struct seq_file *s, void *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) static void _qp_stats_seq_stop(struct seq_file *s, void *iter_ptr)
__releases(RCU) __releases(RCU)
{ {
rcu_read_unlock(); rcu_read_unlock();
} }
......
...@@ -656,10 +656,6 @@ struct qp_iter *qp_iter_init(struct hfi1_ibdev *dev) ...@@ -656,10 +656,6 @@ struct qp_iter *qp_iter_init(struct hfi1_ibdev *dev)
iter->dev = dev; iter->dev = dev;
iter->specials = dev->rdi.ibdev.phys_port_cnt * 2; iter->specials = dev->rdi.ibdev.phys_port_cnt * 2;
if (qp_iter_next(iter)) {
kfree(iter);
return NULL;
}
return iter; return iter;
} }
......
...@@ -189,27 +189,32 @@ static int _ctx_stats_seq_show(struct seq_file *s, void *v) ...@@ -189,27 +189,32 @@ static int _ctx_stats_seq_show(struct seq_file *s, void *v)
DEBUGFS_FILE(ctx_stats) DEBUGFS_FILE(ctx_stats)
static void *_qp_stats_seq_start(struct seq_file *s, loff_t *pos) static void *_qp_stats_seq_start(struct seq_file *s, loff_t *pos)
__acquires(RCU)
{ {
struct qib_qp_iter *iter; struct qib_qp_iter *iter;
loff_t n = *pos; loff_t n = *pos;
rcu_read_lock();
iter = qib_qp_iter_init(s->private); iter = qib_qp_iter_init(s->private);
/* stop calls rcu_read_unlock */
rcu_read_lock();
if (!iter) if (!iter)
return NULL; return NULL;
while (n--) { do {
if (qib_qp_iter_next(iter)) { if (qib_qp_iter_next(iter)) {
kfree(iter); kfree(iter);
return NULL; return NULL;
} }
} } while (n--);
return iter; return iter;
} }
static void *_qp_stats_seq_next(struct seq_file *s, void *iter_ptr, static void *_qp_stats_seq_next(struct seq_file *s, void *iter_ptr,
loff_t *pos) loff_t *pos)
__must_hold(RCU)
{ {
struct qib_qp_iter *iter = iter_ptr; struct qib_qp_iter *iter = iter_ptr;
...@@ -224,6 +229,7 @@ static void *_qp_stats_seq_next(struct seq_file *s, void *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) static void _qp_stats_seq_stop(struct seq_file *s, void *iter_ptr)
__releases(RCU)
{ {
rcu_read_unlock(); rcu_read_unlock();
} }
......
...@@ -573,10 +573,6 @@ struct qib_qp_iter *qib_qp_iter_init(struct qib_ibdev *dev) ...@@ -573,10 +573,6 @@ struct qib_qp_iter *qib_qp_iter_init(struct qib_ibdev *dev)
return NULL; return NULL;
iter->dev = dev; iter->dev = dev;
if (qib_qp_iter_next(iter)) {
kfree(iter);
return NULL;
}
return iter; return iter;
} }
......
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