• Mike Marciniszyn's avatar
    IB/hfi1,IB/qib: Fix qp_stats sleep with rcu read lock held · c62fb260
    Mike Marciniszyn authored
    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>
    c62fb260
qp.c 25.9 KB