IB/hfi1,IB/qib: Fix qp_stats sleep with rcu read lock held
authorMike Marciniszyn <mike.marciniszyn@intel.com>
Fri, 12 Aug 2016 15:17:37 +0000 (11:17 -0400)
committerDoug Ledford <dledford@redhat.com>
Mon, 22 Aug 2016 18:31:34 +0000 (14:31 -0400)
commitc62fb260a86dde3df5b2905432caa0e9f6898434
treeeeb8e1aaef184bdd08cc088ead5d10add86923c6
parentabb658ef0529488cfa75e79a2a9f894cb95eaec3
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: 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>
drivers/infiniband/hw/hfi1/debugfs.c
drivers/infiniband/hw/hfi1/qp.c
drivers/infiniband/hw/qib/qib_debugfs.c
drivers/infiniband/hw/qib/qib_qp.c