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authorJiri Slaby <jslaby@suse.cz>2016-05-13 11:38:49 +0300
committerMarcel Holtmann <marcel@holtmann.org>2016-05-13 17:50:23 +0300
commitbf389cabb3b8079c23f9762e62b05f291e2d5e99 (patch)
treecdabbad6ea9f84aa6549672934f1fcf5eed3fbcc /net/bluetooth/hci_core.c
parented7cbbce544856b20e5811de373cf92e92499771 (diff)
downloadlinux-bf389cabb3b8079c23f9762e62b05f291e2d5e99.tar.xz
Bluetooth: fix power_on vs close race
With all the latest fixes applied, I am still able to reproduce this (and other) warning(s): WARNING: CPU: 1 PID: 19684 at ../kernel/workqueue.c:4092 destroy_workqueue+0x70a/0x770() ... Call Trace: [<ffffffff819fee81>] ? dump_stack+0xb3/0x112 [<ffffffff8117377e>] ? warn_slowpath_common+0xde/0x140 [<ffffffff811ce68a>] ? destroy_workqueue+0x70a/0x770 [<ffffffff811739ae>] ? warn_slowpath_null+0x2e/0x40 [<ffffffff811ce68a>] ? destroy_workqueue+0x70a/0x770 [<ffffffffa0c944c9>] ? hci_unregister_dev+0x2a9/0x720 [bluetooth] [<ffffffffa0b301db>] ? vhci_release+0x7b/0xf0 [hci_vhci] [<ffffffffa0b30160>] ? vhci_flush+0x50/0x50 [hci_vhci] [<ffffffff8117cd73>] ? do_exit+0x863/0x2b90 This is due to race present in the hci_unregister_dev path. hdev->power_on work races with hci_dev_do_close. One tries to open, the other tries to close, leading to warning like the above. (Another example is a warning in kobject_get or kobject_put depending on who wins the race.) Fix this by switching those two racers to ensure hdev->power_on never triggers while hci_dev_do_close is in progress. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Diffstat (limited to 'net/bluetooth/hci_core.c')
-rw-r--r--net/bluetooth/hci_core.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 2713fc86e85a..45a9fc68c677 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3139,10 +3139,10 @@ void hci_unregister_dev(struct hci_dev *hdev)
list_del(&hdev->list);
write_unlock(&hci_dev_list_lock);
- hci_dev_do_close(hdev);
-
cancel_work_sync(&hdev->power_on);
+ hci_dev_do_close(hdev);
+
if (!test_bit(HCI_INIT, &hdev->flags) &&
!hci_dev_test_flag(hdev, HCI_SETUP) &&
!hci_dev_test_flag(hdev, HCI_CONFIG)) {