The 8250 handle_irq callback is not just called from the interrupt handler but also from a timer callback when polling (e.g. for ports without an interrupt line). Consequently the callback must explicitly disable interrupts to avoid a potential deadlock with another interrupt in polled mode.

Fix up the two paths in the freescale callback that failed to re-enable interrupts when polling.

Fixes: 853a9ae29e97 ("serial: 8250: fix handle_irq locking") Cc: stable@vger.kernel.org # 5.13 Reported-by: Dan Carpenter error27@gmail.com Link: https://lore.kernel.org/r/Y/xYzqp4ogmOF5t0@kili Signed-off-by: Johan Hovold johan@kernel.org --- drivers/tty/serial/8250/8250_fsl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_fsl.c b/drivers/tty/serial/8250/8250_fsl.c index 8aad15622a2e..8adfaa183f77 100644 --- a/drivers/tty/serial/8250/8250_fsl.c +++ b/drivers/tty/serial/8250/8250_fsl.c @@ -34,7 +34,7 @@ int fsl8250_handle_irq(struct uart_port *port)

iir = port->serial_in(port, UART_IIR); if (iir & UART_IIR_NO_INT) { - spin_unlock(&up->port.lock); + spin_unlock_irqrestore(&up->port.lock, flags); return 0; }

@@ -42,7 +42,7 @@ int fsl8250_handle_irq(struct uart_port *port) if (unlikely(up->lsr_saved_flags & UART_LSR_BI)) { up->lsr_saved_flags &= ~UART_LSR_BI; port->serial_in(port, UART_RX); - spin_unlock(&up->port.lock); + spin_unlock_irqrestore(&up->port.lock, flags); return 1; }