Messages in this thread Patch in this message | | | Date | Tue, 24 Jan 2017 15:29:34 +0800 | From | jeffy <> | Subject | Re: [PATCH] Bluetooth: hidp: might sleep error in hidp_session_thread |
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Hi brian,
On 01/24/2017 10:31 AM, Brian Norris wrote: > Hi Jeffy, > > On Fri, Jan 20, 2017 at 09:52:08PM +0800, Jeffy Chen wrote: >> [ 39.044329] do not call blocking ops when !TASK_RUNNING; state=1 set >> at [<ffffffbffc290358>] hidp_session_thread+0x110/0x568 [hidp] >> ... >> [ 40.159664] Call trace: >> [ 40.162122] [<ffffffc00024ae08>] __might_sleep+0x64/0x90 >> [ 40.167443] [<ffffffc00080568c>] lock_sock_nested+0x30/0x78 >> [ 40.173047] [<ffffffbffc1b3ca0>] l2cap_sock_sendmsg+0x90/0xf0 >> [bluetooth] >> [ 40.179842] [<ffffffc0008012c4>] sock_sendmsg+0x4c/0x68 >> [ 40.185072] [<ffffffc000801414>] kernel_sendmsg+0x54/0x68 >> [ 40.190477] [<ffffffbffc28f4d0>] hidp_send_frame+0x78/0xa0 [hidp] >> [ 40.196574] [<ffffffbffc28f53c>] hidp_process_transmit+0x44/0x98 >> [hidp] >> [ 40.203191] [<ffffffbffc2905ac>] hidp_session_thread+0x364/0x568 >> [hidp] > Am I crazy, or are several other protocols broken like this too? I see a > similar structure in net/bluetooth/bnep/core.c and > net/bluetooth/cmtp/core.c, at least, each of which also call > kernel_sendmsg(), which might be an l2cap socket (...I think? I'm not a > bluetooth expert really). Thanx, uploaded a new serial of patchset, which contains hidp & cmtp & bnep:9534023/9534025/9534027 > >> Following (https://lwn.net/Articles/628628/). >> >> Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com> >> --- >> >> net/bluetooth/hidp/core.c | 15 +++++++++------ >> 1 file changed, 9 insertions(+), 6 deletions(-) >> >> diff --git a/net/bluetooth/hidp/core.c b/net/bluetooth/hidp/core.c >> index 0bec458..bfd3fb8 100644 >> --- a/net/bluetooth/hidp/core.c >> +++ b/net/bluetooth/hidp/core.c >> @@ -1180,7 +1180,9 @@ static void hidp_session_run(struct hidp_session *session) >> struct sock *ctrl_sk = session->ctrl_sock->sk; >> struct sock *intr_sk = session->intr_sock->sk; >> struct sk_buff *skb; >> + DEFINE_WAIT_FUNC(wait, woken_wake_function); >> >> + add_wait_queue(sk_sleep(intr_sk), &wait); >> for (;;) { >> /* >> * This thread can be woken up two ways: >> @@ -1188,12 +1190,10 @@ static void hidp_session_run(struct hidp_session *session) >> * session->terminate flag and wakes this thread up. >> * - Via modifying the socket state of ctrl/intr_sock. This >> * thread is woken up by ->sk_state_changed(). >> - * >> - * Note: set_current_state() performs any necessary >> - * memory-barriers for us. >> */ >> - set_current_state(TASK_INTERRUPTIBLE); >> >> + /* Ensure session->terminate is updated */ >> + smp_mb__before_atomic(); >> if (atomic_read(&session->terminate)) >> break; >> >> @@ -1227,11 +1227,14 @@ static void hidp_session_run(struct hidp_session *session) >> hidp_process_transmit(session, &session->ctrl_transmit, >> session->ctrl_sock); >> >> - schedule(); >> + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); > I think this looks mostly good, except what about the > hidp_session_terminate() condition? In that case, you're running > wake_up_process() -- which won't set WQ_FLAG_WOKEN for us. So what > happens if we see a hidp_session_terminate() call in between the check > for the ->terminate count, but before we call wait_woken()? IIUC, I > think we'll just ignore the call and keep waiting for the next wake > signal. > > I think you might need to rework hidp_session_terminate() too, to > actually target the wait queue and not just the processes. > > IIUC, of course. I could be wrong... Ok, that make sense, thanx for point that out. > > Brian > >> } >> + remove_wait_queue(sk_sleep(intr_sk), &wait); >> >> atomic_inc(&session->terminate); >> - set_current_state(TASK_RUNNING); >> + >> + /* Ensure session->terminate is updated */ >> + smp_mb__after_atomic(); >> } >> >> /* >> -- >> 2.1.4 >> >> > >
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