tty: serial: amba-pl011: fix cancel_delayed_work() usage

PL011 calls del_timer_sync() (via cancel_delayed_work()) from atomic context.
Fix it.

 ======================================================
 [ INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected ]
 3.0.8+ #1188
 ------------------------------------------------------
 kworker/u:0/5 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
  (&(&uap->clk_off_work)->timer){+.-...}, at: [<c01d82b4>] del_timer_sync+0x0/0xc8

 and this task is already holding:
  (&port_lock_key){-.-...}, at: [<c03ca2b0>] pl011_clock_on+0x80/0xc4
 which would create a new lock dependency:
  (&port_lock_key){-.-...} -> (&(&uap->clk_off_work)->timer){+.-...}

 but this new dependency connects a HARDIRQ-irq-safe lock:
  (&port_lock_key){-.-...}
 ... which became HARDIRQ-irq-safe at:
   [<c01fc734>] mark_irqflags+0x68/0x170
   [<c01ff788>] __lock_acquire+0x598/0x788
   [<c01fff84>] lock_acquire+0x10c/0x130
   [<c06513cc>] _raw_spin_lock_irqsave+0x5c/0x98
   [<c03cb788>] pl011_int+0x10/0x128
   [<c0217a80>] handle_irq_event_percpu+0x98/0x1f4
   [<c0217c18>] handle_irq_event+0x3c/0x5c
   [<c021a0f4>] handle_fasteoi_irq+0xc8/0x100
   [<c02175e4>] generic_handle_irq+0x28/0x30
   [<c0197078>] asm_do_IRQ+0x78/0xb8
   [<c019cc90>] __irq_svc+0x50/0xf4
   [<c04b21a0>] enter_sleep+0x550/0x608
   [<c04b02ac>] cpuidle_idle_call+0x1c4/0x33c
   [<c019e1fc>] cpu_idle+0xa4/0x10c
   [<c0008a28>] start_kernel+0x228/0x27c
   [<00008040>] 0x8040

 to a HARDIRQ-irq-unsafe lock:
  (&(&uap->clk_off_work)->timer){+.-...}
 ... which became HARDIRQ-irq-unsafe at:
 ...  [<c01fc7b8>] mark_irqflags+0xec/0x170
   [<c01ff788>] __lock_acquire+0x598/0x788
   [<c01fff84>] lock_acquire+0x10c/0x130
   [<c01d78a4>] call_timer_fn+0x68/0x1e4
   [<c01d7be8>] run_timer_softirq+0x1c8/0x224
   [<c01d0244>] __do_softirq+0x110/0x23c
   [<c01d05b8>] irq_exit+0x5c/0xc0
   [<c0197308>] do_local_timer+0x50/0x80
   [<c019cc90>] __irq_svc+0x50/0xf4
   [<c064f30c>] __mutex_unlock_slowpath+0x150/0x17c
   [<c02c6d08>] sysfs_addrm_finish+0x10/0x74
   [<c02c5afc>] sysfs_add_file_mode+0x70/0xb0
   [<c02c8368>] create_files+0x7c/0xb4
   [<c02c8458>] internal_create_group+0xb8/0x118
   [<c03f08a8>] device_add_groups+0x1c/0x70
   [<c03f0e2c>] device_add_attrs+0x50/0xa8
   [<c03f0f94>] device_add+0x110/0x2b4
   [<c0601114>] hci_register_sysfs+0x54/0x114
   [<c05f2fec>] hci_register_dev+0x378/0x4d8
   [<c04dbe58>] register_bluetooth+0xb4/0x124
   [<c04dbf44>] probe_common+0x7c/0xcc
   [<c06482e0>] btcg2900_evt_probe+0x38/0x6c
   [<c03f3f18>] platform_drv_probe+0x18/0x1c
   [<c03f2c98>] really_probe+0x98/0x148
   [<c03f2d90>] driver_probe_device+0x48/0x60
   [<c03f21f0>] bus_for_each_drv+0x44/0x74
   [<c03f2f10>] device_attach+0x78/0xa4
   [<c03f2028>] bus_probe_device+0x24/0x40
   [<c03f0ff8>] device_add+0x174/0x2b4
   [<c03f4530>] platform_device_add+0x104/0x160
   [<c0405d34>] mfd_add_device+0x194/0x1d4
   [<c0405ef8>] mfd_add_devices+0x70/0xbc
   [<c04d6eec>] work_power_off_chip+0x11c/0x1c8
   [<c01e250c>] process_one_work+0x2ac/0x4c8
   [<c01e29f8>] worker_thread+0x144/0x234
   [<c01e8280>] kthread+0x80/0x88
   [<c019dc88>] kernel_thread_exit+0x0/0x8

 other info that might help us debug this:

  Possible interrupt unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&(&uap->clk_off_work)->timer);
                                local_irq_disable();
                                lock(&port_lock_key);
                                lock(&(&uap->clk_off_work)->timer);
   <Interrupt>
     lock(&port_lock_key);

  *** DEADLOCK ***

Change-Id: I55d565d484baaee2dc76f258a5066aacbb6e6dee
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>

ST-Ericsson ID: 413918
ST-Ericsson Linux next: NA
ST-Ericsson FOSS-OUT ID: Trivial

Change-Id: I1a45effb0afeb4344f03ca500a5b0767bd760ec3
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/47174
Reviewed-by: QABUILD
Reviewed-by: Shreshtha Kumar SAHU <shreshthakumar.sahu@stericsson.com>
Reviewed-by: Rabin VINCENT <rabin.vincent@stericsson.com>
Tested-by: Rabin VINCENT <rabin.vincent@stericsson.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index bed430df99e..d356b940382 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1306,7 +1306,7 @@ static void pl011_clock_on(struct uart_port *port)
 		}
 		/* fallthrough */
 	case PL011_CLK_REQUEST_OFF:
-		cancel_delayed_work(&uap->clk_off_work);
+		__cancel_delayed_work(&uap->clk_off_work);
 		uap->clk_state = PL011_CLK_ON;
 		break;
 	default:
@@ -1321,7 +1321,7 @@ static void pl011_clock_check(struct uart_amba_port *uap)
 	/* Reshedule work during off request  */
 	if (uap->clk_state == PL011_CLK_REQUEST_OFF)
 		/* New TX - restart work */
-		if (cancel_delayed_work(&uap->clk_off_work))
+		if (__cancel_delayed_work(&uap->clk_off_work))
 			schedule_delayed_work(&uap->clk_off_work,
 						uap->clk_off_delay);
 }