dmaengine: rcar-dmac: Disable interrupts while stopping channels

During system reboot or halt, with lockdep enabled:

    ================================
    WARNING: inconsistent lock state
    4.18.0-rc1-salvator-x-00002-g9203dbec90a68103 xen-troops#41 Tainted: G        W
    --------------------------------
    inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
    reboot/2779 [HC0[0]:SC0[0]:HE1:SE1] takes:
    0000000098ae4ad3 (&(&rchan->lock)->rlock){?.-.}, at: rcar_dmac_shutdown+0x58/0x6c
    {IN-HARDIRQ-W} state was registered at:
      lock_acquire+0x208/0x238
      _raw_spin_lock+0x40/0x54
      rcar_dmac_isr_channel+0x28/0x200
      __handle_irq_event_percpu+0x1c0/0x3c8
      handle_irq_event_percpu+0x34/0x88
      handle_irq_event+0x48/0x78
      handle_fasteoi_irq+0xc4/0x12c
      generic_handle_irq+0x18/0x2c
      __handle_domain_irq+0xa8/0xac
      gic_handle_irq+0x78/0xbc
      el1_irq+0xec/0x1c0
      arch_cpu_idle+0xe8/0x1bc
      default_idle_call+0x2c/0x30
      do_idle+0x144/0x234
      cpu_startup_entry+0x20/0x24
      rest_init+0x27c/0x290
      start_kernel+0x430/0x45c
    irq event stamp: 12177
    hardirqs last  enabled at (12177): [<ffffff800881d804>] _raw_spin_unlock_irq+0x2c/0x4c
    hardirqs last disabled at (12176): [<ffffff800881d638>] _raw_spin_lock_irq+0x1c/0x60
    softirqs last  enabled at (11948): [<ffffff8008081da8>] __do_softirq+0x160/0x4ec
    softirqs last disabled at (11935): [<ffffff80080ec948>] irq_exit+0xa0/0xfc

    other info that might help us debug this:
     Possible unsafe locking scenario:

	   CPU0
	   ----
      lock(&(&rchan->lock)->rlock);
      <Interrupt>
	lock(&(&rchan->lock)->rlock);

     *** DEADLOCK ***

    3 locks held by reboot/2779:
     #0: 00000000bfabfa74 (reboot_mutex){+.+.}, at: sys_reboot+0xdc/0x208
     #1: 00000000c75d8c3a (&dev->mutex){....}, at: device_shutdown+0xc8/0x1c4
     #2: 00000000ebec58ec (&dev->mutex){....}, at: device_shutdown+0xd8/0x1c4

    stack backtrace:
    CPU: 6 PID: 2779 Comm: reboot Tainted: G        W         4.18.0-rc1-salvator-x-00002-g9203dbec90a68103 xen-troops#41
    Hardware name: Renesas Salvator-X 2nd version board based on r8a7795 ES2.0+ (DT)
    Call trace:
     dump_backtrace+0x0/0x148
     show_stack+0x14/0x1c
     dump_stack+0xb0/0xf0
     print_usage_bug.part.26+0x1c4/0x27c
     mark_lock+0x38c/0x610
     __lock_acquire+0x3fc/0x14d4
     lock_acquire+0x208/0x238
     _raw_spin_lock+0x40/0x54
     rcar_dmac_shutdown+0x58/0x6c
     platform_drv_shutdown+0x20/0x2c
     device_shutdown+0x160/0x1c4
     kernel_restart_prepare+0x34/0x3c
     kernel_restart+0x14/0x5c
     sys_reboot+0x160/0x208
     el0_svc_naked+0x30/0x34

rcar_dmac_stop_all_chan() takes the channel lock while stopping a
channel, but does not disable interrupts, leading to a deadlock when a
DMAC interrupt comes in.  Before, the same code block was called from an
interrupt handler, hence taking the spinlock was sufficient.

Fix this by disabling local interrupts while taking the spinlock.

Fixes: 9203dbe ("dmaengine: rcar-dmac: don't use DMAC error interrupt")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
(cherry picked from commit 45c9a60)
Signed-off-by: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>

drivers/dma/sh/rcar-dmac.c

@@ -820,9 +820,9 @@ static void rcar_dmac_stop_all_chan(struct rcar_dmac *dmac)
 		struct rcar_dmac_chan *chan = &dmac->channels[i];
 
 		/* Stop and reinitialize the channel. */
-		spin_lock(&chan->lock);
+		spin_lock_irq(&chan->lock);
 		rcar_dmac_chan_halt(chan);
-		spin_unlock(&chan->lock);
+		spin_unlock_irq(&chan->lock);
 	}
 }