From: Rabin Vincent <[email protected]> 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 <[email protected]> Signed-off-by: Rabin Vincent <[email protected]> Reviewed-by: Srinidhi Kasagar <[email protected]> Reviewed-by: Bibek Basu <[email protected]> Reviewed-by: Shreshtha Kumar Sahu <[email protected]> Signed-off-by: Linus Walleij <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/tty/serial/amba-pl011.c | 14 ++++++++++++++ 1 files changed, 14 insertions(+), 0 deletions(-) diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index ce843d0..6800f5f 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); } -- 1.7.8.3 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
