linux-kernel - xilinx_uartps.c: suppress "may be used uninitialised" warning

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Message-ID: <20190731160557.6a09c3e1@canb.auug.org.au>
Date:   Wed, 31 Jul 2019 16:05:57 +1000
From:   Stephen Rothwell <sfr@...b.auug.org.au>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Linux PPC Development List <linuxppc-dev@...ts.ozlabs.org>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jiri Slaby <jslaby@...e.com>,
        Michal Simek <michal.simek@...inx.com>,
        Linux Serial List <linux-serial@...r.kernel.org>,
        Linus ARM List <linux-arm-kernel@...ts.infradead.org>
Subject: xilinx_uartps.c: suppress "may be used uninitialised" warning

From 31753a44c62c4fdf6e8a72994ae6861dbde49c11 Mon Sep 17 00:00:00 2001
From: Stephen Rothwell <sfr@...b.auug.org.au>
Date: Wed, 31 Jul 2019 16:00:52 +1000
Subject: [PATCH] xilinx_uartps.c: suppress "may be used uninitialised" warning

A powerpc allyesconfig build produces this warning:

In file included from include/linux/radix-tree.h:16,
                 from include/linux/idr.h:15,
                 from include/linux/kernfs.h:13,
                 from include/linux/sysfs.h:16,
                 from include/linux/kobject.h:20,
                 from include/linux/device.h:16,
                 from include/linux/platform_device.h:13,
                 from drivers/tty/serial/xilinx_uartps.c:16:
drivers/tty/serial/xilinx_uartps.c: In function 'cdns_uart_console_write':
include/linux/spinlock.h:288:3: warning: 'flags' may be used uninitialized in this function [-Wmaybe-uninitialized]
   _raw_spin_unlock_irqrestore(lock, flags); \
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/tty/serial/xilinx_uartps.c:1197:16: note: 'flags' was declared here
  unsigned long flags;
                ^~~~~

It looks like gcc just can't track the relationship between "locked"
and "flags", and it is obvious that "flags" won't be used when "locked"
is zero, so the simplest thing is to initialise flags.

Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Jiri Slaby <jslaby@...e.com>
Cc: Michal Simek <michal.simek@...inx.com>
Signed-off-by: Stephen Rothwell <sfr@...b.auug.org.au>
---
 drivers/tty/serial/xilinx_uartps.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

This has been like this for a very long time, but this is now one of
the few remaining warnings produced by the powerpc allyesconfig build,
so it would be good to get rid of it.

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index f145946f659b..da4563aaaf5c 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1194,7 +1194,7 @@ static void cdns_uart_console_write(struct console *co, const char *s,
 				unsigned int count)
 {
 	struct uart_port *port = console_port;
-	unsigned long flags;
+	unsigned long flags = 0;
 	unsigned int imr, ctrl;
 	int locked = 1;
 
-- 
2.22.0

-- 
Cheers,
Stephen Rothwell

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