[stable][PATCH] pch_uart: Add eg20t_port lock field, avoid recursive spinlocks

commit 2588aba002d14e938c2f56d299ecf3e7ce1302a5 upstream. pch_uart_interrupt() takes priv->port.lock which leads to two recursive spinlock calls if low_latency==1 or CONFIG_PREEMPT_RT_FULL=y (one otherwise): pch_uart_interrupt spin_lock_irqsave(priv->port.lock, flags) case

[stable][PATCH] pch_uart: Add eg20t_port lock field, avoid recursive spinlocks

commit 2588aba002d14e938c2f56d299ecf3e7ce1302a5 upstream. pch_uart_interrupt() takes priv-port.lock which leads to two recursive spinlock calls if low_latency==1 or CONFIG_PREEMPT_RT_FULL=y (one otherwise): pch_uart_interrupt spin_lock_irqsave(priv-port.lock, flags) case PCH_UART_IID_RDR_TO