From ef605fdb33883d687cff5ba75095a91b313b4966 Mon Sep 17 00:00:00 2001 From: Rabin Vincent Date: Tue, 17 Jan 2012 11:52:28 +0100 Subject: [PATCH] serial: amba-pl011: lock console writes against interrupts Protect against pl011_console_write() and the interrupt for the console UART running concurrently on different CPUs. Otherwise the console_write could spin for a long time waiting for the UART to become not busy, while the other CPU continuously services UART interrupts and keeps the UART busy. The checks for sysrq and oops_in_progress are taken from 8250.c. Cc: stable Signed-off-by: Rabin Vincent Reviewed-by: Srinidhi Kasagar Reviewed-by: Bibek Basu Reviewed-by: Shreshtha Kumar Sahu Signed-off-by: Linus Walleij Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/amba-pl011.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index ce843d058e02..6800f5f26241 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -1751,9 +1751,19 @@ pl011_console_write(struct console *co, const char *s, unsigned int count) { struct uart_amba_port *uap = amba_ports[co->index]; unsigned int status, old_cr, new_cr; + unsigned long flags; + int locked = 1; clk_enable(uap->clk); + local_irq_save(flags); + if (uap->port.sysrq) + locked = 0; + else if (oops_in_progress) + locked = spin_trylock(&uap->port.lock); + else + spin_lock(&uap->port.lock); + /* * First save the CR then disable the interrupts */ @@ -1773,6 +1783,10 @@ pl011_console_write(struct console *co, const char *s, unsigned int count) } while (status & UART01x_FR_BUSY); writew(old_cr, uap->port.membase + UART011_CR); + if (locked) + spin_unlock(&uap->port.lock); + local_irq_restore(flags); + clk_disable(uap->clk); } -- 2.39.5