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authorPeter Hurley <peter@hurleysoftware.com>2011-06-30 13:53:53 -0400
committerGustavo F. Padovan <padovan@profusion.mobi>2011-06-30 14:47:50 -0400
commit7bb59df83b190817f56c4e2fec3078d99d906ad4 (patch)
tree371add6842b2620dbedad6d4d240681f09118fe8
parent7ac28817536797fd40e9646452183606f9e17f71 (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>
-rw-r--r--net/bluetooth/hidp/core.c18
-rw-r--r--net/bluetooth/hidp/hidp.h1
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
470static void hidp_set_timer(struct hidp_session *session) 471static 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,
1060err_add_device: 1062err_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
1065unlink: 1068unlink:
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];