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Bluetooth: cmtp: Fix deadlock in session deletion

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Commit fada4ac339 introduced the usage of kthread API.
kthread_stop is a blocking function which returns only when
the thread exits. In this case, the thread can't exit because it's
waiting for the write lock, which is being held by cmtp_del_connection()
which is waiting for the thread to exit -- deadlock.

Revert cmtp_reset_ctr to its original behavior: non-blocking signalling
for the session to terminate.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
This commit is contained in:
Peter Hurley
2011-08-05 10:44:21 -04:00
committed by Gustavo F. Padovan
parent 751c10a568
commit 7176522cdc
3 changed files with 6 additions and 3 deletions
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3
net/bluetooth/cmtp/capi.c
View File

@@ -386,7 +386,8 @@ static void cmtp_reset_ctr(struct capi_ctr *ctrl)
capi_ctr_down(ctrl); capi_ctr_down(ctrl);
kthread_stop(session->task); atomic_inc(&session->terminate);
wake_up_process(session->task);
} }
static void cmtp_register_appl(struct capi_ctr *ctrl, __u16 appl, capi_register_params *rp) static void cmtp_register_appl(struct capi_ctr *ctrl, __u16 appl, capi_register_params *rp)

1
net/bluetooth/cmtp/cmtp.h
View File

@@ -81,6 +81,7 @@ struct cmtp_session {
char name[BTNAMSIZ]; char name[BTNAMSIZ];
atomic_t terminate;
struct task_struct *task; struct task_struct *task;
wait_queue_head_t wait; wait_queue_head_t wait;

5
net/bluetooth/cmtp/core.c
View File

@@ -295,7 +295,7 @@ static int cmtp_session(void *arg)
while (1) { while (1) {
set_current_state(TASK_INTERRUPTIBLE); set_current_state(TASK_INTERRUPTIBLE);
if (kthread_should_stop()) if (atomic_read(&session->terminate))
break; break;
if (sk->sk_state != BT_CONNECTED) if (sk->sk_state != BT_CONNECTED)
break; break;
@@ -416,7 +416,8 @@ int cmtp_del_connection(struct cmtp_conndel_req *req)
skb_queue_purge(&session->transmit); skb_queue_purge(&session->transmit);
/* Stop session thread */ /* Stop session thread */
kthread_stop(session->task); atomic_inc(&session->terminate);
wake_up_process(session->task);
} else } else
err = -ENOENT; err = -ENOENT;