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 15:47:50 -0300 |
commit | 7bb59df83b190817f56c4e2fec3078d99d906ad4 (patch) | |
tree | 371add6842b2620dbedad6d4d240681f09118fe8 /net/bluetooth/hidp | |
parent | 7ac28817536797fd40e9646452183606f9e17f71 (diff) | |
download | linux-7bb59df83b190817f56c4e2fec3078d99d906ad4.tar.bz2 |
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/hidp')
-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) { struct hidp_session *session = (struct hidp_session *) arg; - kthread_stop(session->task); + atomic_inc(&session->terminate); + wake_up_process(session->task); } static void hidp_set_timer(struct hidp_session *session) @@ -535,7 +536,8 @@ static void hidp_process_hid_control(struct hidp_session *session, skb_queue_purge(&session->ctrl_transmit); skb_queue_purge(&session->intr_transmit); - kthread_stop(session->task); + atomic_inc(&session->terminate); + wake_up_process(current); } } @@ -706,9 +708,8 @@ static int hidp_session(void *arg) add_wait_queue(sk_sleep(intr_sk), &intr_wait); session->waiting_for_startup = 0; wake_up_interruptible(&session->startup_queue); - while (!kthread_should_stop()) { - set_current_state(TASK_INTERRUPTIBLE); - + set_current_state(TASK_INTERRUPTIBLE); + while (!atomic_read(&session->terminate)) { if (ctrl_sk->sk_state != BT_CONNECTED || intr_sk->sk_state != BT_CONNECTED) break; @@ -726,6 +727,7 @@ static int hidp_session(void *arg) hidp_process_transmit(session); schedule(); + set_current_state(TASK_INTERRUPTIBLE); } set_current_state(TASK_RUNNING); 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, err_add_device: hid_destroy_device(session->hid); session->hid = NULL; - kthread_stop(session->task); + atomic_inc(&session->terminate); + wake_up_process(session->task); unlink: hidp_del_timer(session); @@ -1111,7 +1114,8 @@ int hidp_del_connection(struct hidp_conndel_req *req) skb_queue_purge(&session->ctrl_transmit); skb_queue_purge(&session->intr_transmit); - kthread_stop(session->task); + atomic_inc(&session->terminate); + wake_up_process(session->task); } } else 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 { uint ctrl_mtu; uint intr_mtu; + atomic_t terminate; struct task_struct *task; unsigned char keys[8]; |