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Commit 74ea66d4 authored by Soren Brinkmann's avatar Soren Brinkmann Committed by Greg Kroah-Hartman
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tty: xuartps: Improve sysrq handling 



Handling magic sysrq included dropping a lock to avoid a deadlock that
happened when cdns_uart_console_write tried to acquire a lock in the
from the sysrq code path. By making the acquisition of the lock in
cdns_uart_console_write depending on port->sysrq, cdns_uart_handle_rx can be
simplified to simply call uart_handle_sysrq.

Suggested-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarSoren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 354fb1a7

drivers/tty/serial/xilinx_uartps.c

+5 −15
Original line number Diff line number Diff line
@@ -220,20 +220,8 @@ static void cdns_uart_handle_rx(struct uart_port *port, unsigned int isrstatus) 
				continue;

		}



#ifdef SUPPORT_SYSRQ

		/*

		 * uart_handle_sysrq_char() doesn't work if

		 * spinlocked, for some reason

		 */

		 if (port->sysrq) {

			spin_unlock(&port->lock);

			if (uart_handle_sysrq_char(port, data)) {

				spin_lock(&port->lock);

		if (uart_handle_sysrq_char(port, data))

			continue;

			}

			spin_lock(&port->lock);

		}

#endif



		port->icount.rx++;
@@ -1128,7 +1116,9 @@ static void cdns_uart_console_write(struct console *co, const char *s, 
	unsigned int imr, ctrl;

	int locked = 1;



	if (oops_in_progress)

	if (port->sysrq)

		locked = 0;

	else if (oops_in_progress)

		locked = spin_trylock_irqsave(&port->lock, flags);

	else

		spin_lock_irqsave(&port->lock, flags);