cpm_uart: Fix cpm uart corruption with PREEMPT_RT

Fix CPM serial port corruption when running with CONFIG_PREEMPT_RT.
Userland usage of console, and kernel printf's were stepping on each others toes.
Also only take lock if not in an oops.

Signed-off-by: Rune Torgersen <runet@innovsys.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

diff --git a/drivers/serial/cpm_uart/cpm_uart_core.c b/drivers/serial/cpm_uart/cpm_uart_core.c
old mode 100644 (file)
new mode 100755 (executable)
index 43f58dc..d389a76
--- a/drivers/serial/cpm_uart/cpm_uart_core.c
+++ b/drivers/serial/cpm_uart/cpm_uart_core.c
@@ -969,6 +969,14 @@ static void cpm_uart_console_write(struct console *co, const char *s,
        unsigned int i;
        cbd_t __iomem *bdp, *bdbase;
        unsigned char *cp;
+       unsigned long flags;
+       int nolock = oops_in_progress;
+
+       if (unlikely(nolock)) {
+               local_irq_save(flags);
+       } else {
+               spin_lock_irqsave(&pinfo->port.lock, flags);
+       }
 
        /* Get the address of the host memory buffer.
         */
@@ -1030,6 +1038,12 @@ static void cpm_uart_console_write(struct console *co, const char *s,
                ;
 
        pinfo->tx_cur = bdp;
+
+       if (unlikely(nolock)) {
+               local_irq_restore(flags);
+       } else {
+               spin_unlock_irqrestore(&pinfo->port.lock, flags);
+       }
 }