The rtnl cannot be held durrng the fcoe_interface_put.
If it is the last reference on the fcoe_interface the
fcoe_ctlr_destroy will be called as a part of the
cleanup, ultimately calling cancel_work_sync(&fip->recv_work);

If we are processing a flogi response we will be in
the recv_work context and we will lock the rtnl to
add a new unicast MAC address. This is how the deadlock
can occur.

The fix is simply to move the rtnl_lock/unlock into
fcoe_interface_cleanup so that it can be unlocked before
fcoe_interface_put is called.

Here is the lockdep report:

Jul 21 11:26:35 bubba [  223.870702]
ul 21 11:26:35 bubba [  223.870704] =======================================================
Jul 21 11:26:35 bubba [  223.871255] [ INFO: possible circular locking dependency detected ]
Jul 21 11:26:35 bubba [  223.871530] 3.0.0-rc7+ #1
Jul 21 11:26:35 bubba [  223.871797] -------------------------------------------------------
Jul 21 11:26:35 bubba [  223.872072] lockdeptest.sh/3464 is trying to acquire lock:
Jul 21 11:26:35 bubba [  223.872345]  ((&fip->recv_work)
Jul 21 11:26:35 bubba ){+.+.+.}
Jul 21 11:26:35 bubba , at:
Jul 21 11:26:35 bubba [<ffffffff810531f1>] wait_on_work+0x0/0xbd
Jul 21 11:26:35 bubba [  223.873022]
Jul 21 11:26:35 bubba [  223.873023] but task is already holding lock:
Jul 21 11:26:35 bubba [  223.873555]  (rtnl_mutex
Jul 21 11:26:35 bubba ){+.+.+.}
Jul 21 11:26:35 bubba , at:
Jul 21 11:26:35 bubba [<ffffffff813e8233>] rtnl_lock+0x12/0x14
Jul 21 11:26:35 bubba [  223.874229]
Jul 21 11:26:35 bubba [  223.874230] which lock already depends on the new lock.
Jul 21 11:26:35 bubba [  223.874231]
Jul 21 11:26:35 bubba [  223.875032]
Jul 21 11:26:35 bubba [  223.875033] the existing dependency chain (in reverse order) is:
Jul 21 11:26:35 bubba [  223.875573]
Jul 21 11:26:35 bubba [  223.875573] -> #1
Jul 21 11:26:35 bubba (rtnl_mutex
Jul 21 11:26:35 bubba ){+.+.+.}
Jul 21 11:26:35 bubba :
Jul 21 11:26:35 bubba [  223.876301]
Jul 21 11:26:35 bubba [<ffffffff8106c14a>] lock_acquire+0xd2/0xf7
Jul 21 11:26:35 bubba [  223.876645]
Jul 21 11:26:35 bubba [<ffffffff8151d975>] __mutex_lock_common+0x47/0x30d
Jul 21 11:26:35 bubba [  223.876991]
Jul 21 11:26:35 bubba [<ffffffff8151dd36>] mutex_lock_nested+0x3b/0x40
Jul 21 11:26:35 bubba [  223.877334]
Jul 21 11:26:35 bubba [<ffffffff813e8233>] rtnl_lock+0x12/0x14
Jul 21 11:26:35 bubba [  223.877675]
Jul 21 11:26:35 bubba [<ffffffffa003d5a0>] fcoe_update_src_mac+0x2b/0x80 [fcoe]
Jul 21 11:26:35 bubba [  223.878022]
Jul 21 11:26:35 bubba [<ffffffffa003d698>] fcoe_flogi_resp+0x5e/0x79 [fcoe]
Jul 21 11:26:35 bubba [  223.878366]
Jul 21 11:26:35 bubba [<ffffffffa001566f>] fc_exch_recv+0x7f5/0x9da [libfc]
Jul 21 11:26:35 bubba [  223.878713]
Jul 21 11:26:35 bubba [<ffffffffa00327d8>] fcoe_ctlr_recv_work+0x71f/0x10dc [libfcoe]
Jul 21 11:26:35 bubba [  223.879258]
Jul 21 11:26:35 bubba [<ffffffff81053761>] process_one_work+0x1d7/0x347
Jul 21 11:26:35 bubba [  223.879601]
Jul 21 11:26:35 bubba [<ffffffff81054ade>] worker_thread+0xf8/0x17c
Jul 21 11:26:35 bubba [  223.879944]
Jul 21 11:26:35 bubba [<ffffffff81058184>] kthread+0x7d/0x85
Jul 21 11:26:35 bubba [  223.880287]
Jul 21 11:26:35 bubba [<ffffffff81526414>] kernel_thread_helper+0x4/0x10
Jul 21 11:26:35 bubba [  223.880634]
Jul 21 11:26:35 bubba [  223.880635] -> #0
Jul 21 11:26:35 bubba ((&fip->recv_work)
Jul 21 11:26:35 bubba ){+.+.+.}
Jul 21 11:26:35 bubba :
Jul 21 11:26:35 bubba [  223.881357]
Jul 21 11:26:35 bubba [<ffffffff8106b93e>] __lock_acquire+0xb1d/0xe2c
Jul 21 11:26:35 bubba [  223.881695]
Jul 21 11:26:35 bubba [<ffffffff8106c14a>] lock_acquire+0xd2/0xf7
Jul 21 11:26:35 bubba [  223.882033]
Jul 21 11:26:35 bubba [<ffffffff81053241>] wait_on_work+0x50/0xbd
Jul 21 11:26:35 bubba [  223.882378]
Jul 21 11:26:35 bubba [<ffffffff81053b32>] __cancel_work_timer+0xb6/0xf4
Jul 21 11:26:35 bubba [  223.882718]
Jul 21 11:26:35 bubba [<ffffffff81053b8a>] cancel_work_sync+0xb/0xd
Jul 21 11:26:35 bubba [  223.883057]
Jul 21 11:26:35 bubba [<ffffffffa00317e6>] fcoe_ctlr_destroy+0x1d/0x67 [libfcoe]
Jul 21 11:26:35 bubba [  223.883399]
Jul 21 11:26:35 bubba [<ffffffffa003e51e>] fcoe_interface_release+0x21/0x45 [fcoe]
Jul 21 11:26:35 bubba [  223.883940]
Jul 21 11:26:35 bubba [<ffffffff811fbbe6>] kref_put+0x43/0x4d
Jul 21 11:26:35 bubba [  223.884280]
Jul 21 11:26:35 bubba [<ffffffffa003ebba>] fcoe_interface_put+0x17/0x19 [fcoe]
Jul 21 11:26:35 bubba [  223.884624]
Jul 21 11:26:35 bubba [<ffffffffa003f2a6>] fcoe_interface_cleanup+0x188/0x193 [fcoe]
Jul 21 11:26:35 bubba [  223.885163]
Jul 21 11:26:35 bubba [<ffffffffa003f303>] fcoe_destroy+0x52/0x72 [fcoe]
Jul 21 11:26:35 bubba [  223.885502]
Jul 21 11:26:35 bubba [<ffffffffa00340a4>] fcoe_transport_destroy+0xab/0x110 [libfcoe]
Jul 21 11:26:35 bubba [  223.886045]
Jul 21 11:26:35 bubba [<ffffffff81056153>] param_attr_store+0x43/0x62
Jul 21 11:26:35 bubba [  223.886385]
Jul 21 11:26:35 bubba [<ffffffff8105602d>] module_attr_store+0x21/0x25
Jul 21 11:26:35 bubba [  223.886728]
Jul 21 11:26:35 bubba [<ffffffff8114c23d>] sysfs_write_file+0x103/0x13f
Jul 21 11:26:35 bubba [  223.887068]
Jul 21 11:26:35 bubba [<ffffffff810f3e7b>] vfs_write+0xa7/0xfa
Jul 21 11:26:35 bubba [  223.887406]
Jul 21 11:26:35 bubba [<ffffffff810f4073>] sys_write+0x45/0x69
Jul 21 11:26:35 bubba [  223.887742]
Jul 21 11:26:35 bubba [<ffffffff815252bb>] system_call_fastpath+0x16/0x1b
Jul 21 11:26:35 bubba [  223.888083]
Jul 21 11:26:35 bubba [  223.888084] other info that might help us debug this:
Jul 21 11:26:35 bubba [  223.888085]
Jul 21 11:26:35 bubba [  223.888879]  Possible unsafe locking scenario:
Jul 21 11:26:35 bubba [  223.888881]
Jul 21 11:26:35 bubba [  223.889411]        CPU0                    CPU1
Jul 21 11:26:35 bubba [  223.889683]        ----                    ----
Jul 21 11:26:35 bubba [  223.889955]   lock(
Jul 21 11:26:35 bubba rtnl_mutex
Jul 21 11:26:35 bubba );
Jul 21 11:26:35 bubba [  223.890349]                                lock(
Jul 21 11:26:35 bubba (&fip->recv_work)
Jul 21 11:26:35 bubba );
Jul 21 11:26:35 bubba [  223.890751]                                lock(
Jul 21 11:26:35 bubba rtnl_mutex
Jul 21 11:26:35 bubba );
Jul 21 11:26:35 bubba [  223.891154]   lock(
Jul 21 11:26:35 bubba (&fip->recv_work)
Jul 21 11:26:35 bubba );
Jul 21 11:26:35 bubba [  223.891549]
Jul 21 11:26:35 bubba [  223.891550]  *** DEADLOCK ***
Jul 21 11:26:35 bubba [  223.891551]
Jul 21 11:26:35 bubba [  223.892347] 6 locks held by lockdeptest.sh/3464:
Jul 21 11:26:35 bubba [  223.892621]  #0:
Jul 21 11:26:35 bubba (&buffer->mutex
Jul 21 11:26:35 bubba ){+.+.+.}
Jul 21 11:26:35 bubba , at:
Jul 21 11:26:35 bubba [<ffffffff8114c171>] sysfs_write_file+0x37/0x13f
Jul 21 11:26:35 bubba [  223.893359]  #1:
Jul 21 11:26:35 bubba (s_active
Jul 21 11:26:35 bubba ){++++.+}
Jul 21 11:26:35 bubba , at:
Jul 21 11:26:35 bubba [<ffffffff8114c21c>] sysfs_write_file+0xe2/0x13f
Jul 21 11:26:35 bubba [  223.894094]  #2:
Jul 21 11:26:35 bubba (param_lock
Jul 21 11:26:35 bubba ){+.+.+.}
Jul 21 11:26:35 bubba , at:
Jul 21 11:26:35 bubba [<ffffffff81056146>] param_attr_store+0x36/0x62
Jul 21 11:26:35 bubba [  223.894835]  #3:
Jul 21 11:26:35 bubba (ft_mutex
Jul 21 11:26:35 bubba ){+.+.+.}
Jul 21 11:26:35 bubba , at:
Jul 21 11:26:35 bubba [<ffffffffa0034017>] fcoe_transport_destroy+0x1e/0x110 [libfcoe]
Jul 21 11:26:35 bubba [  223.895574]  #4:
Jul 21 11:26:35 bubba (fcoe_config_mutex
Jul 21 11:26:35 bubba ){+.+.+.}
Jul 21 11:26:35 bubba , at:
Jul 21 11:26:35 bubba [<ffffffffa003f2c9>] fcoe_destroy+0x18/0x72 [fcoe]
Jul 21 11:26:35 bubba [  223.896314]  #5:
Jul 21 11:26:35 bubba (rtnl_mutex
Jul 21 11:26:35 bubba ){+.+.+.}
Jul 21 11:26:35 bubba , at:
Jul 21 11:26:35 bubba [<ffffffff813e8233>] rtnl_lock+0x12/0x14
Jul 21 11:26:35 bubba [  223.897047]
Jul 21 11:26:35 bubba [  223.897048] stack backtrace:
Jul 21 11:26:35 bubba [  223.897578] Pid: 3464, comm: lockdeptest.sh Not tainted 3.0.0-rc7+ #1
Jul 21 11:26:35 bubba [  223.897853] Call Trace:
Jul 21 11:26:35 bubba [  223.898128]  [<ffffffff81068e16>] print_circular_bug+0x1f8/0x209
Jul 21 11:26:35 bubba [  223.898416]  [<ffffffff8106b93e>] __lock_acquire+0xb1d/0xe2c
Jul 21 11:26:35 bubba [  223.898699]  [<ffffffff810531f1>] ? wait_on_cpu_work+0xe6/0xe6
Jul 21 11:26:35 bubba [  223.898982]  [<ffffffff8106c14a>] lock_acquire+0xd2/0xf7
Jul 21 11:26:35 bubba [  223.899263]  [<ffffffff810531f1>] ? wait_on_cpu_work+0xe6/0xe6
Jul 21 11:26:35 bubba [  223.899547]  [<ffffffff8104a097>] ? mod_timer+0x8f/0x98
Jul 21 11:26:35 bubba [  223.899827]  [<ffffffff81053241>] wait_on_work+0x50/0xbd
Jul 21 11:26:35 bubba [  223.900108]  [<ffffffff810531f1>] ? wait_on_cpu_work+0xe6/0xe6
Jul 21 11:26:35 bubba [  223.900390]  [<ffffffff81053b32>] __cancel_work_timer+0xb6/0xf4
Jul 21 11:26:35 bubba [  223.900671]  [<ffffffff81053b8a>] cancel_work_sync+0xb/0xd
Jul 21 11:26:35 bubba [  223.900953]  [<ffffffffa00317e6>] fcoe_ctlr_destroy+0x1d/0x67 [libfcoe]
Jul 21 11:26:35 bubba [  223.901237]  [<ffffffffa003e51e>] fcoe_interface_release+0x21/0x45 [fcoe]
Jul 21 11:26:35 bubba [  223.901522]  [<ffffffffa003e4fd>] ? fcoe_enable+0x6b/0x6b [fcoe]
Jul 21 11:26:35 bubba [  223.901803]  [<ffffffff811fbbe6>] kref_put+0x43/0x4d
Jul 21 11:26:35 bubba [  223.902083]  [<ffffffffa003ebba>] fcoe_interface_put+0x17/0x19 [fcoe]
Jul 21 11:26:35 bubba [  223.902367]  [<ffffffffa003f2a6>] fcoe_interface_cleanup+0x188/0x193 [fcoe]
Jul 21 11:26:35 bubba [  223.902653]  [<ffffffff8151dd36>] ? mutex_lock_nested+0x3b/0x40
Jul 21 11:26:35 bubba [  223.902939]  [<ffffffffa003f303>] fcoe_destroy+0x52/0x72 [fcoe]
Jul 21 11:26:35 bubba [  223.903223]  [<ffffffffa00340a4>] fcoe_transport_destroy+0xab/0x110 [libfcoe]
Jul 21 11:26:35 bubba [  223.903508]  [<ffffffff81056153>] param_attr_store+0x43/0x62
Jul 21 11:26:35 bubba [  223.903792]  [<ffffffff8105602d>] module_attr_store+0x21/0x25
Jul 21 11:26:35 bubba [  223.904075]  [<ffffffff8114c23d>] sysfs_write_file+0x103/0x13f
Jul 21 11:26:35 bubba [  223.904357]  [<ffffffff810f3e7b>] vfs_write+0xa7/0xfa
Jul 21 11:26:35 bubba [  223.904642]  [<ffffffff810f51d6>] ? fget_light+0x35/0x96
Jul 21 11:26:35 bubba [  223.904923]  [<ffffffff810f4073>] sys_write+0x45/0x69
Jul 21 11:26:35 bubba [  223.905204]  [<ffffffff815252bb>] system_call_fastpath+0x16/0x1b
Jul 21 11:26:36 bubba [  223.964438] ixgbe 0000:05:00.0: eth3: detected SFP+: 5
Jul 21 11:26:37 bubba [  225.196702] ixgbe 0000:05:00.0: eth3: NIC Link is Up 10 Gbps, Flow Control: None
Signed-off-by: Robert Love <robert.w.love@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Reviewed-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>