[PATCH 5.7 12/24] usb: musb: jz4740: Prevent lockup when CONFIG_SMP is set

[Greg Kroah-Hartman]

From: Paul Cercueil <paul@xxxxxxxxxxxxxxx>

commit 685f5f24108a5f3481da70ee75a1b18b9de34257 upstream.

The function dma_controller_irq() locks up the exact same spinlock we
locked before calling it, which obviously resulted in a deadlock when
CONFIG_SMP was enabled. This flew under the radar as none of the boards
supported by this driver needs SMP.

Fixes: 57aadb46bd63 ("usb: musb: jz4740: Add support for DMA")

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
Signed-off-by: Bin Liu <b-liu@xxxxxx>
Link: https://lore.kernel.org/r/20200525025049.3400-6-b-liu@xxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/musb/jz4740.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/usb/musb/jz4740.c
+++ b/drivers/usb/musb/jz4740.c
@@ -30,11 +30,11 @@ static irqreturn_t jz4740_musb_interrupt
 	irqreturn_t	retval = IRQ_NONE, retval_dma = IRQ_NONE;
 	struct musb	*musb = __hci;
 
-	spin_lock_irqsave(&musb->lock, flags);
-
 	if (IS_ENABLED(CONFIG_USB_INVENTRA_DMA) && musb->dma_controller)
 		retval_dma = dma_controller_irq(irq, musb->dma_controller);
 
+	spin_lock_irqsave(&musb->lock, flags);
+
 	musb->int_usb = musb_readb(musb->mregs, MUSB_INTRUSB);
 	musb->int_tx = musb_readw(musb->mregs, MUSB_INTRTX);
 	musb->int_rx = musb_readw(musb->mregs, MUSB_INTRRX);