[PATCH] powerpc: Bad NULL pointer check in udbg_uart_getc_poll

We have some code in udbg_uart_getc_poll that tries to protect
against a NULL udbg_uart_in, but gets it all wrong.

Found with the LLVM static analyzer (scan-build).

Fixes: 309257484cc1 ("powerpc: Cleanup udbg_16550 and add support for LPC PIO-only UARTs")
Cc: stable@vger.kernel.org
Signed-off-by: Anton Blanchard <redacted>
---
 arch/powerpc/kernel/udbg_16550.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/udbg_16550.c b/arch/powerpc/kernel/udbg_16550.c
index 6e7c492..3faf393 100644
--- a/arch/powerpc/kernel/udbg_16550.c
+++ b/arch/powerpc/kernel/udbg_16550.c

@@ -69,7 +69,9 @@ static void udbg_uart_putc(char c)
 
 static int udbg_uart_getc_poll(void)
 {
-	if (!udbg_uart_in || !(udbg_uart_in(UART_LSR) & LSR_DR))
+	if (!udbg_uart_in)
+		return -1;
+	if (!(udbg_uart_in(UART_LSR) & LSR_DR))
 		return udbg_uart_in(UART_RBR);
 	return -1;
 }

-- 
1.9.1