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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: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Soren Brinkmann 2016-01-11 17:41:39 -08:00 committed by Greg Kroah-Hartman
parent 354fb1a7d7
commit 74ea66d4ca
1 changed files with 5 additions and 15 deletions
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20
drivers/tty/serial/xilinx_uartps.c
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@ -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);
continue;
}
spin_lock(&port->lock);
}
#endif
if (uart_handle_sysrq_char(port, data))
continue;
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);