tree 158a3865fe6e1a6766ea813a2cdf186f0e605850
parent cf370066ac5c7d5fdf384fef24b8ba48a481ffa5
author Eddie Wai <eddie.wai@broadcom.com> 1386804621 -0800
committer James Bottomley <JBottomley@Parallels.com> 1394903867 -0700

[SCSI] bnx2fc: Fixed scsi_remove_target soft lockup when rmmod bnx2x

The problem has been identified to be a change in the scsi_remove_device
path where a call to the pm_runtime_set_memalloc_noio was added when
del_gendisk is called in this path.  Note that the new pm routine
attempts to cycle through all parent devices from the FC target device
to set the memalloc_noio flag.  Because of this new change, a dependency
was created between the FC target device and the parent netdev device
in the destroy path.

In order to synchronized the destroy paths, bnx2fc has been modified
to flush all destroy workqueues in the NETDEV_UNREGISTER return path.

[    4.123584] BUG: soft lockup - CPU#8 stuck for 22s! [kworker/8:3:8082]
[    4.123713] Call Trace:
[    4.123719]  [<ffffffff815dfbe0>] klist_next+0x20/0xf0
[    4.123725]  [<ffffffff813e9220>] ? pm_save_wakeup_count+0x70/0x70
[    4.123731]  [<ffffffff813d9e4e>] device_for_each_child+0x4e/0x70
[    4.123735]  [<ffffffff813e9554>] pm_runtime_set_memalloc_noio+0x94/0xf0
[    4.123740]  [<ffffffff812d4d74>] del_gendisk+0x264/0x2a0
[    4.123747]  [<ffffffffa00c6dc9>] sd_remove+0x69/0xb0 [sd_mod]
[    4.123751]  [<ffffffff813de24f>] __device_release_driver+0x7f/0xf0
[    4.123754]  [<ffffffff813de2e3>] device_release_driver+0x23/0x30
[    4.123757]  [<ffffffff813ddab4>] bus_remove_device+0xf4/0x170
[    4.123760]  [<ffffffff813da475>] device_del+0x135/0x1d0
[    4.123765]  [<ffffffff81411b75>] __scsi_remove_device+0xc5/0xd0
[    4.123768]  [<ffffffff81411ba6>] scsi_remove_device+0x26/0x40
[    4.123770]  [<ffffffff81411d40>] scsi_remove_target+0x160/0x210
[    4.123775]  [<ffffffffa0420e4c>] fc_rport_final_delete+0xac/0x1f0 [scsi_transport_fc]
[    4.123780]  [<ffffffff810774ab>] process_one_work+0x17b/0x460
[    4.123783]  [<ffffffff8107825b>] worker_thread+0x11b/0x400
[    4.123786]  [<ffffffff81078140>] ? rescuer_thread+0x3e0/0x3e0
[    4.123791]  [<ffffffff8107e9c0>] kthread+0xc0/0xd0
[    4.123794]  [<ffffffff8107e900>] ? kthread_create_on_node+0x110/0x110
[    4.123798]  [<ffffffff8160ceec>] ret_from_fork+0x7c/0xb0
[    4.123801]  [<ffffffff8107e900>] ? kthread_create_on_node+0x110/0x110

Signed-off-by: Eddie Wai <eddie.wai@broadcom.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>