From: Rabin Vincent <rabin.vincent@xxxxxxxxxxxxxx>
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 <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Rabin Vincent <rabin.vincent@xxxxxxxxxxxxxx>
Reviewed-by: Srinidhi Kasagar <srinidhi.kasagar@xxxxxxxxxxxxxx>
Reviewed-by: Bibek Basu <bibek.basu@xxxxxxxxxxxxxx>
Reviewed-by: Shreshtha Kumar Sahu <shreshthakumar.sahu@xxxxxxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
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
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