NFS: Replace flush_scheduled_work with cancel_work_sync() and friends
This will avoid deadlocks of the form:
stack backtrace:
[<c0104fda>] show_trace_log_lvl+0x1a/0x30
[<c0105c02>] show_trace+0x12/0x20
[<c0105d15>] dump_stack+0x15/0x20
[<c013ee42>] __lock_acquire+0xc22/0x1030
[<c013f2b1>] lock_acquire+0x61/0x80
[<c012edd9>] flush_workqueue+0x49/0x70
[<c012ee0d>] flush_scheduled_work+0xd/0x10
[<dcf55c0c>] nfs_release_automount_timer+0x2c/0x30 [nfs]
[<dcf45d8e>] nfs_free_server+0x9e/0xd0 [nfs]
[<dcf4e626>] nfs_kill_super+0x16/0x20 [nfs]
[<c017b38d>] deactivate_super+0x7d/0xa0
[<c018f94b>] mntput_no_expire+0x4b/0x80
[<c018fd94>] expire_mount_list+0xe4/0x140
[<c0191219>] mark_mounts_for_expiry+0x99/0xb0
[<dcf55d1d>] nfs_expire_automounts+0xd/0x40 [nfs]
[<c012e61b>] run_workqueue+0x12b/0x1e0
[<c012f05b>] worker_thread+0x9b/0x100
[<c0131c72>] kthread+0x42/0x70
[<c0104c0f>] kernel_thread_helper+0x7/0x18
=======================
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2 files changed