diff options
author | Peter Hurley <peter@hurleysoftware.com> | 2011-06-30 13:53:53 -0400 |
---|---|---|
committer | Gustavo F. Padovan <padovan@profusion.mobi> | 2011-06-30 14:47:50 -0400 |
commit | 7bb59df83b190817f56c4e2fec3078d99d906ad4 (patch) | |
tree | 371add6842b2620dbedad6d4d240681f09118fe8 /net/bluetooth | |
parent | 7ac28817536797fd40e9646452183606f9e17f71 (diff) |
Bluetooth: Fix hidp disconnect deadlocks and lost wakeup
Partial revert of commit aabf6f89. When the hidp session thread
was converted from kernel_thread to kthread, the atomic/wakeups
were replaced with kthread_stop. kthread_stop has blocking semantics
which are inappropriate for the hidp session kthread. In addition,
the kthread signals itself to terminate in hidp_process_hid_control()
- it cannot do this with kthread_stop().
Lastly, a wakeup can be lost if the wakeup happens between checking
for the loop exit condition and setting the current state to
TASK_INTERRUPTIBLE. (Without appropriate synchronization mechanisms,
the task state should not be changed between the condition test and
the yield - via schedule() - as this creates a race between the
wakeup and resetting the state back to interruptible.)
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Diffstat (limited to 'net/bluetooth')
-rw-r--r-- | net/bluetooth/hidp/core.c | 18 | ||||
-rw-r--r-- | net/bluetooth/hidp/hidp.h | 1 |
2 files changed, 12 insertions, 7 deletions
diff --git a/net/bluetooth/hidp/core.c b/net/bluetooth/hidp/core.c index c405a954a603..43b4c2deb7cc 100644 --- a/net/bluetooth/hidp/core.c +++ b/net/bluetooth/hidp/core.c | |||
@@ -464,7 +464,8 @@ static void hidp_idle_timeout(unsigned long arg) | |||
464 | { | 464 | { |
465 | struct hidp_session *session = (struct hidp_session *) arg; | 465 | struct hidp_session *session = (struct hidp_session *) arg; |
466 | 466 | ||
467 | kthread_stop(session->task); | 467 | atomic_inc(&session->terminate); |
468 | wake_up_process(session->task); | ||
468 | } | 469 | } |
469 | 470 | ||
470 | static void hidp_set_timer(struct hidp_session *session) | 471 | static void hidp_set_timer(struct hidp_session *session) |
@@ -535,7 +536,8 @@ static void hidp_process_hid_control(struct hidp_session *session, | |||
535 | skb_queue_purge(&session->ctrl_transmit); | 536 | skb_queue_purge(&session->ctrl_transmit); |
536 | skb_queue_purge(&session->intr_transmit); | 537 | skb_queue_purge(&session->intr_transmit); |
537 | 538 | ||
538 | kthread_stop(session->task); | 539 | atomic_inc(&session->terminate); |
540 | wake_up_process(current); | ||
539 | } | 541 | } |
540 | } | 542 | } |
541 | 543 | ||
@@ -706,9 +708,8 @@ static int hidp_session(void *arg) | |||
706 | add_wait_queue(sk_sleep(intr_sk), &intr_wait); | 708 | add_wait_queue(sk_sleep(intr_sk), &intr_wait); |
707 | session->waiting_for_startup = 0; | 709 | session->waiting_for_startup = 0; |
708 | wake_up_interruptible(&session->startup_queue); | 710 | wake_up_interruptible(&session->startup_queue); |
709 | while (!kthread_should_stop()) { | 711 | set_current_state(TASK_INTERRUPTIBLE); |
710 | set_current_state(TASK_INTERRUPTIBLE); | 712 | while (!atomic_read(&session->terminate)) { |
711 | |||
712 | if (ctrl_sk->sk_state != BT_CONNECTED || | 713 | if (ctrl_sk->sk_state != BT_CONNECTED || |
713 | intr_sk->sk_state != BT_CONNECTED) | 714 | intr_sk->sk_state != BT_CONNECTED) |
714 | break; | 715 | break; |
@@ -726,6 +727,7 @@ static int hidp_session(void *arg) | |||
726 | hidp_process_transmit(session); | 727 | hidp_process_transmit(session); |
727 | 728 | ||
728 | schedule(); | 729 | schedule(); |
730 | set_current_state(TASK_INTERRUPTIBLE); | ||
729 | } | 731 | } |
730 | set_current_state(TASK_RUNNING); | 732 | set_current_state(TASK_RUNNING); |
731 | remove_wait_queue(sk_sleep(intr_sk), &intr_wait); | 733 | remove_wait_queue(sk_sleep(intr_sk), &intr_wait); |
@@ -1060,7 +1062,8 @@ int hidp_add_connection(struct hidp_connadd_req *req, struct socket *ctrl_sock, | |||
1060 | err_add_device: | 1062 | err_add_device: |
1061 | hid_destroy_device(session->hid); | 1063 | hid_destroy_device(session->hid); |
1062 | session->hid = NULL; | 1064 | session->hid = NULL; |
1063 | kthread_stop(session->task); | 1065 | atomic_inc(&session->terminate); |
1066 | wake_up_process(session->task); | ||
1064 | 1067 | ||
1065 | unlink: | 1068 | unlink: |
1066 | hidp_del_timer(session); | 1069 | hidp_del_timer(session); |
@@ -1111,7 +1114,8 @@ int hidp_del_connection(struct hidp_conndel_req *req) | |||
1111 | skb_queue_purge(&session->ctrl_transmit); | 1114 | skb_queue_purge(&session->ctrl_transmit); |
1112 | skb_queue_purge(&session->intr_transmit); | 1115 | skb_queue_purge(&session->intr_transmit); |
1113 | 1116 | ||
1114 | kthread_stop(session->task); | 1117 | atomic_inc(&session->terminate); |
1118 | wake_up_process(session->task); | ||
1115 | } | 1119 | } |
1116 | } else | 1120 | } else |
1117 | err = -ENOENT; | 1121 | err = -ENOENT; |
diff --git a/net/bluetooth/hidp/hidp.h b/net/bluetooth/hidp/hidp.h index 19e95004b286..af1bcc823f26 100644 --- a/net/bluetooth/hidp/hidp.h +++ b/net/bluetooth/hidp/hidp.h | |||
@@ -142,6 +142,7 @@ struct hidp_session { | |||
142 | uint ctrl_mtu; | 142 | uint ctrl_mtu; |
143 | uint intr_mtu; | 143 | uint intr_mtu; |
144 | 144 | ||
145 | atomic_t terminate; | ||
145 | struct task_struct *task; | 146 | struct task_struct *task; |
146 | 147 | ||
147 | unsigned char keys[8]; | 148 | unsigned char keys[8]; |