[PATCH] usb: otg-fsm: Cancel HNP polling work when not used
Jun Li
jun.li at nxp.com
Wed Jun 29 03:56:42 PDT 2016
Hi
> -----Original Message-----
> From: Peter Chen [mailto:hzpeterchen at gmail.com]
> Sent: Wednesday, June 29, 2016 5:44 PM
> To: Stephen Boyd <stephen.boyd at linaro.org>
> Cc: Peter Chen <peter.chen at nxp.com>; Felipe Balbi <balbi at kernel.org>;
> linux-arm-kernel at lists.infradead.org; linux-kernel at vger.kernel.org; linux-
> usb at vger.kernel.org; Jun Li <jun.li at nxp.com>; Greg Kroah-Hartman
> <gregkh at linuxfoundation.org>
> Subject: Re: [PATCH] usb: otg-fsm: Cancel HNP polling work when not used
>
> On Mon, Jun 27, 2016 at 06:18:27PM -0700, Stephen Boyd wrote:
> > We setup the HNP polling worker, but we never stop it. The OTG state
> > machine can go round and round and keep reinitializing the worker even
> > while it's actively running. That's bad, and debug objects catches it.
> > Fix this by canceling the work when we leave the A_HOST or B_HOST
> > states.
> >
> > [otg_set_state] Set state: a_wait_bcon usb 2-1: USB disconnect,
> > device number 2 [otg_statemachine] quit statemachine, changed = 1
> > [otg_set_state] Set state: a_host <HNP Polling started>
> > [otg_statemachine] quit statemachine, changed = 1 usb 2-1: new
> > low-speed USB device number 3 using ci_hdrc usb 2-1: New USB device
> > found, idVendor=03f0, idProduct=134a usb 2-1: New USB device strings:
> > Mfr=1, Product=2, SerialNumber=0 usb 2-1: Product: HP USB Optical
> > Mouse usb 2-1: Manufacturer: PixArt
> > input: PixArt HP USB Optical Mouse as
> > /devices/platform/soc/f9a55000.usb/ci_hdrc.0/usb2/2-1/2-1:1.0/0003:03F
> > 0:134A.0002/input/input1 hid-generic 0003:03F0:134A.0002: input: USB
> > HID v1.11 Mouse [PixArt HP USB Optical Mouse] on
> > usb-ci_hdrc.0-1/input0 [otg_set_state] Set state: a_wait_bcon usb
> > 2-1: USB disconnect, device number 3 [otg_statemachine] quit
> > statemachine, changed = 1 [otg_set_state] Set state: a_host <HNP
> > Polling started> ------------[ cut here ]------------
> > WARNING: CPU: 2 PID: 95 at lib/debugobjects.c:263
> > debug_print_object+0x98/0xc0
> > ODEBUG: init active (active state 0) object type: timer_list hint:
> > delayed_work_timer_fn+0x0/0x2c Modules linked in: phy_qcom_usb_hsic
> > phy_qcom_usb_hs ci_hdrc_msm ci_hdrc
> > CPU: 2 PID: 95 Comm: kworker/u8:1 Not tainted
> > 4.7.0-rc1-00043-g1f22f3b65c44-dirty #442 Hardware name: Qualcomm
> > (Flattened Device Tree)
> > Workqueue: ci_otg ci_otg_work [ci_hdrc] [<c031067c>]
> > (unwind_backtrace) from [<c030cbf0>] (show_stack+0x20/0x24)
> > [<c030cbf0>] (show_stack) from [<c060cec8>] (dump_stack+0x7c/0x9c)
> > [<c060cec8>] (dump_stack) from [<c031f8a4>] (__warn+0xe4/0x110)
> > [<c031f8a4>] (__warn) from [<c031f9a0>] (warn_slowpath_fmt+0x48/0x50)
> > [<c031f9a0>] (warn_slowpath_fmt) from [<c06289c0>]
> > (debug_print_object+0x98/0xc0) [<c06289c0>] (debug_print_object) from
> > [<c0628bbc>] (__debug_object_init+0xcc/0x3bc) [<c0628bbc>]
> > (__debug_object_init) from [<c0628ed0>] (debug_object_init+0x24/0x2c)
> > [<c0628ed0>] (debug_object_init) from [<c037ceb0>]
> > (init_timer_key+0x24/0x120) [<c037ceb0>] (init_timer_key) from
> > [<c07b3f1c>] (otg_start_hnp_polling+0x7c/0xbc) [<c07b3f1c>]
> > (otg_start_hnp_polling) from [<c074543c>] (otg_set_state+0x740/0xc20)
> > [<c074543c>] (otg_set_state) from [<c0745d98>]
> > (otg_statemachine+0x47c/0x4ac) [<c0745d98>] (otg_statemachine) from
> > [<bf00c808>] (ci_otg_fsm_work+0x48/0x1a0 [ci_hdrc]) [<bf00c808>]
> > (ci_otg_fsm_work [ci_hdrc]) from [<bf007428>] (ci_otg_work+0xd4/0x218
> > [ci_hdrc]) [<bf007428>] (ci_otg_work [ci_hdrc]) from [<c0338cac>]
> > (process_one_work+0x154/0x4b4) [<c0338cac>] (process_one_work) from
> > [<c033908c>] (worker_thread+0x38/0x4d0) [<c033908c>] (worker_thread)
> > from [<c033f0a0>] (kthread+0xe8/0x104) [<c033f0a0>] (kthread) from
> > [<c0308ed8>] (ret_from_fork+0x14/0x3c)
> >
> > Cc: Li Jun <jun.li at nxp.com>
> > Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> > Fixes: ae57e97a9521 ("usb: common: otg-fsm: add HNP polling support")
> > Signed-off-by: Stephen Boyd <stephen.boyd at linaro.org>
> > ---
> > drivers/usb/common/usb-otg-fsm.c | 14 ++++++++++++++
> > 1 file changed, 14 insertions(+)
> >
> > diff --git a/drivers/usb/common/usb-otg-fsm.c
> > b/drivers/usb/common/usb-otg-fsm.c
> > index 9059b7dc185e..73eec8c12235 100644
> > --- a/drivers/usb/common/usb-otg-fsm.c
> > +++ b/drivers/usb/common/usb-otg-fsm.c
> > @@ -61,6 +61,18 @@ static int otg_set_protocol(struct otg_fsm *fsm, int
> protocol)
> > return 0;
> > }
> >
> > +static void otg_stop_hnp_polling(struct otg_fsm *fsm) {
> > + /*
> > + * The memory of host_req_flag should be allocated by
> > + * controller driver, otherwise, hnp polling is not started.
> > + */
> > + if (!fsm->host_req_flag)
> > + return;
> > +
> > + cancel_delayed_work_sync(&fsm->hnp_polling_work);
> > +}
> > +
> > /* Called when leaving a state. Do state clean up jobs here */
> > static void otg_leave_state(struct otg_fsm *fsm, enum usb_otg_state
> > old_state) { @@ -84,6 +96,7 @@ static void otg_leave_state(struct
> > otg_fsm *fsm, enum usb_otg_state old_state)
> > fsm->b_ase0_brst_tmout = 0;
> > break;
> > case OTG_STATE_B_HOST:
> > + otg_stop_hnp_polling(fsm);
> > break;
> > case OTG_STATE_A_IDLE:
> > fsm->adp_prb = 0;
> > @@ -97,6 +110,7 @@ static void otg_leave_state(struct otg_fsm *fsm, enum
> usb_otg_state old_state)
> > fsm->a_wait_bcon_tmout = 0;
> > break;
> > case OTG_STATE_A_HOST:
> > + otg_stop_hnp_polling(fsm);
> > otg_del_timer(fsm, A_WAIT_ENUM);
> > break;
> > case OTG_STATE_A_SUSPEND:
> > --
>
> It introduces circular locking after applying it, otg_statemachine calls
> otg_leave_state, and otg_leave_state calls otg_statemachine again due to
> flush work, see below dump:
How did you trigger this locking issue? I did some simple tests with
this patch but no problems found.
>
> I suggest moving initialization/flush hnp polling work to chipidea driver.
>
Since the HNP polling is done in common driver completely, so I think
it's not proper to move some of it into controller driver.
Li Jun
> [ 183.086987] ======================================================
> [ 183.093183] [ INFO: possible circular locking dependency detected ]
> [ 183.099471] 4.7.0-rc4-00012-gf1f333f-dirty #856 Not tainted
> [ 183.105059] -------------------------------------------------------
> [ 183.111341] kworker/0:2/114 is trying to acquire lock:
> [ 183.116492] (&ci->fsm.lock){+.+.+.}, at: [<806118dc>]
> otg_statemachine+0x20/0x470
> [ 183.124199]
> [ 183.124199] but task is already holding lock:
> [ 183.130052] ((&(&fsm->hnp_polling_work)->work)){+.+...}, at:
> [<80140368>] process_one_work+0x128/0x418 [ 183.139568] [ 183.139568]
> which lock already depends on the new lock.
> [ 183.139568]
> [ 183.147765]
> [ 183.147765] the existing dependency chain (in reverse order) is:
> [ 183.155265]
> -> #1 ((&(&fsm->hnp_polling_work)->work)){+.+...}:
> [ 183.161371] [<8013e97c>] flush_work+0x44/0x234
> [ 183.166469] [<801411a8>] __cancel_work_timer+0x98/0x1c8
> [ 183.172347] [<80141304>] cancel_delayed_work_sync+0x14/0x18
> [ 183.178570] [<80610ef8>] otg_set_state+0x290/0xc54
> [ 183.184011] [<806119d0>] otg_statemachine+0x114/0x470
> [ 183.189712] [<8060a590>] ci_otg_fsm_work+0x40/0x190
> [ 183.195239] [<806054d0>] ci_otg_work+0xcc/0x1e4
> [ 183.200430] [<801403d4>] process_one_work+0x194/0x418
> [ 183.206136] [<8014068c>] worker_thread+0x34/0x4fc
> [ 183.211489] [<80146d08>] kthread+0xdc/0xf8
> [ 183.216238] [<80108ab0>] ret_from_fork+0x14/0x24
> [ 183.221514]
> -> #0 (&ci->fsm.lock){+.+.+.}:
> [ 183.225880] [<8016ff94>] lock_acquire+0x78/0x98
> [ 183.231062] [<80947c18>] mutex_lock_nested+0x54/0x3ec
> [ 183.236773] [<806118dc>] otg_statemachine+0x20/0x470
> [ 183.242388] [<80611df4>] otg_hnp_polling_work+0xc8/0x1a4
> [ 183.248352] [<801403d4>] process_one_work+0x194/0x418
> [ 183.254055] [<8014068c>] worker_thread+0x34/0x4fc
> [ 183.259409] [<80146d08>] kthread+0xdc/0xf8
> [ 183.264154] [<80108ab0>] ret_from_fork+0x14/0x24
> [ 183.269424]
> [ 183.269424] other info that might help us debug this:
> [ 183.269424]
> [ 183.277451] Possible unsafe locking scenario:
> [ 183.277451]
> [ 183.283389] CPU0 CPU1
> [ 183.287931] ---- ----
> [ 183.292473] lock((&(&fsm->hnp_polling_work)->work));
> [ 183.297665] lock(&ci->fsm.lock);
> [ 183.303639]
> lock((&(&fsm->hnp_polling_work)->work));
> [ 183.311347] lock(&ci->fsm.lock);
> [ 183.314801]
> [ 183.314801] *** DEADLOCK ***
> [ 183.314801]
> [ 183.320745] 2 locks held by kworker/0:2/114:
> [ 183.325028] #0: ("events"){.+.+.+}, at: [<80140368>]
> process_one_work+0x128/0x418
> [ 183.332817] #1:
> ((&(&fsm->hnp_polling_work)->work)){+.+...}, at: [<80140368>]
> process_one_work+0x128/0x418
> [ 183.342772]
> [ 183.342772] stack backtrace:
> [ 183.347160] CPU: 0 PID: 114 Comm: kworker/0:2 Not tainted 4.7.0-rc4-
> 00012-gf1f333f-dirty #856 [ 183.355699] Hardware name: Freescale i.MX6
> SoloX (Device
> Tree)
> [ 183.361561] Workqueue: events otg_hnp_polling_work [ 183.366388]
> Backtrace:
> [ 183.368891] [<8010d014>] (dump_backtrace) from [<8010d208>]
> (show_stack+0x18/0x1c)
> [ 183.376479] r6:600001d3 r5:00000000 r4:80f21d3c r3:00000002
> [ 183.382265] [<8010d1f0>] (show_stack) from [<803f158c>]
> (dump_stack+0xb4/0xe8)
> [ 183.389521] [<803f14d8>] (dump_stack) from [<8016c2b4>]
> (print_circular_bug+0x1d0/0x314)
> [ 183.397625] r10:81760be8 r9:00000000 r8:bdb7bc00 r7:bdb7c0e0
> r6:810c7074 r5:810ea174
> [ 183.405585] r4:810c7074 r3:00000002
> [ 183.409231] [<8016c0e4>] (print_circular_bug) from [<8016fa8c>]
> (__lock_acquire+0x196c/0x1ab4) [ 183.417857] r10:80f21e1c r9:00000002
> r8:00000001 r7:8174e47c
> r6:00000002 r5:bdb7bc00
> [ 183.425814] r4:00000026 r3:bdb7c0c0
> [ 183.429459] [<8016e120>] (__lock_acquire) from [<8016ff94>]
> (lock_acquire+0x78/0x98)
> [ 183.437218] r10:bdb701cc r9:bdbafeb0 r8:00001388 r7:00000001
> r6:806118dc r5:60000153 [ 183.445175] r4:00000000 [ 183.447758]
> [<8016ff1c>] (lock_acquire) from [<80947c18>]
> (mutex_lock_nested+0x54/0x3ec)
> [ 183.455864] r7:bdb7bc00 r6:8174e47c r5:806118dc r4:00000000
> [ 183.461645] [<80947bc4>] (mutex_lock_nested) from [<806118dc>]
> (otg_statemachine+0x20/0x470) [ 183.470097] r10:00000001 r9:bdbafeb0
> r8:00001388 r7:bd3ef000
> r6:00000009 r5:bdb701cc
> [ 183.478057] r4:bdb70120
> [ 183.480641] [<806118bc>] (otg_statemachine) from [<80611df4>]
> (otg_hnp_polling_work+0xc8/0x1a4)
> [ 183.489354] r5:bdb70214 r4:00000000
> [ 183.493006] [<80611d2c>] (otg_hnp_polling_work) from [<801403d4>]
> (process_one_work+0x194/0x418) [ 183.501805] r8:00000000 r7:be7c4400
> r6:be7c0ec0 r5:bdb70214
> r4:bdb2d600
> [ 183.508650] [<80140240>] (process_one_work) from [<8014068c>]
> (worker_thread+0x34/0x4fc)
> [ 183.516754] r10:bdb2d600 r9:be7c0ec0 r8:80f02100 r7:be7c0ef4
> r6:00000008 r5:bdb2d618
> [ 183.524712] r4:be7c0ec0
> [ 183.527297] [<80140658>] (worker_thread) from [<80146d08>]
> (kthread+0xdc/0xf8)
> [ 183.534534] r10:00000000 r9:00000000 r8:00000000 r7:80140658
> r6:bdb2d600 r5:bdb51000
> [ 183.542492] r4:00000000
> [ 183.545081] [<80146c2c>] (kthread) from [<80108ab0>]
> (ret_from_fork+0x14/0x24)
> [ 183.552317] r7:00000000 r6:00000000 r5:80146c2c r4:bdb51000
>
>
> --
>
> Best Regards,
> Peter Chen
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