diff options
| author | Valentin Priescu <priescuv@amazon.com> | 2014-05-20 22:28:50 +0200 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2014-05-28 14:17:32 -0400 |
| commit | 814d04e7dfc4a9cf7e36656afe2da5c0c08dde2b (patch) | |
| tree | fc7ecdbe2026aaebafc52f513cc9e46aee58684a /drivers/block/xen-blkback/common.h | |
| parent | 1c339ef74b431bab18bc11fb69e46db294070dd3 (diff) | |
| download | linux-814d04e7dfc4a9cf7e36656afe2da5c0c08dde2b.tar.bz2 | |
xen-blkback: defer freeing blkif to avoid blocking xenwatch
Currently xenwatch blocks in VBD disconnect, waiting for all pending I/O
requests to finish. If the VBD is attached to a hot-swappable disk, then
xenwatch can hang for a long period of time, stalling other watches.
INFO: task xenwatch:39 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
ffff880057f01bd0 0000000000000246 ffff880057f01ac0 ffffffff810b0782
ffff880057f01ad0 00000000000131c0 0000000000000004 ffff880057edb040
ffff8800344c6080 0000000000000000 ffff880058c00ba0 ffff880057edb040
Call Trace:
[<ffffffff810b0782>] ? irq_to_desc+0x12/0x20
[<ffffffff8128f761>] ? list_del+0x11/0x40
[<ffffffff8147a080>] ? wait_for_common+0x60/0x160
[<ffffffff8147bcef>] ? _raw_spin_lock_irqsave+0x2f/0x50
[<ffffffff8147bd49>] ? _raw_spin_unlock_irqrestore+0x19/0x20
[<ffffffff8147a26a>] schedule+0x3a/0x60
[<ffffffffa018fe6a>] xen_blkif_disconnect+0x8a/0x100 [xen_blkback]
[<ffffffff81079f70>] ? wake_up_bit+0x40/0x40
[<ffffffffa018ffce>] xen_blkbk_remove+0xae/0x1e0 [xen_blkback]
[<ffffffff8130b254>] xenbus_dev_remove+0x44/0x90
[<ffffffff81345cb7>] __device_release_driver+0x77/0xd0
[<ffffffff81346488>] device_release_driver+0x28/0x40
[<ffffffff813456e8>] bus_remove_device+0x78/0xe0
[<ffffffff81342c9f>] device_del+0x12f/0x1a0
[<ffffffff81342d2d>] device_unregister+0x1d/0x60
[<ffffffffa0190826>] frontend_changed+0xa6/0x4d0 [xen_blkback]
[<ffffffffa019c252>] ? frontend_changed+0x192/0x650 [xen_netback]
[<ffffffff8130ae50>] ? cmp_dev+0x60/0x60
[<ffffffff81344fe4>] ? bus_for_each_dev+0x94/0xa0
[<ffffffff8130b06e>] xenbus_otherend_changed+0xbe/0x120
[<ffffffff8130b4cb>] frontend_changed+0xb/0x10
[<ffffffff81309c82>] xenwatch_thread+0xf2/0x130
[<ffffffff81079f70>] ? wake_up_bit+0x40/0x40
[<ffffffff81309b90>] ? xenbus_directory+0x80/0x80
[<ffffffff810799d6>] kthread+0x96/0xa0
[<ffffffff81485934>] kernel_thread_helper+0x4/0x10
[<ffffffff814839f3>] ? int_ret_from_sys_call+0x7/0x1b
[<ffffffff8147c17c>] ? retint_restore_args+0x5/0x6
[<ffffffff81485930>] ? gs_change+0x13/0x13
With this patch, when there is still pending I/O, the actual disconnect
is done by the last reference holder (last pending I/O request). In this
case, xenwatch doesn't block indefinitely.
Signed-off-by: Valentin Priescu <priescuv@amazon.com>
Reviewed-by: Steven Kady <stevkady@amazon.com>
Reviewed-by: Steven Noonan <snoonan@amazon.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers/block/xen-blkback/common.h')
| -rw-r--r-- | drivers/block/xen-blkback/common.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h index be052773ad03..f65b807e3236 100644 --- a/drivers/block/xen-blkback/common.h +++ b/drivers/block/xen-blkback/common.h @@ -314,7 +314,7 @@ struct xen_blkif { unsigned long long st_rd_sect; unsigned long long st_wr_sect; - wait_queue_head_t waiting_to_free; + struct work_struct free_work; /* Thread shutdown wait queue. */ wait_queue_head_t shutdown_wq; }; @@ -361,7 +361,7 @@ struct pending_req { #define xen_blkif_put(_b) \ do { \ if (atomic_dec_and_test(&(_b)->refcnt)) \ - wake_up(&(_b)->waiting_to_free);\ + schedule_work(&(_b)->free_work);\ } while (0) struct phys_req { |