linux-kernel - [PATCH 5/9] net: fddi/defxx: avoid warning about uninitialized variable use

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Message-Id: <1453903507-3427225-6-git-send-email-arnd@arndb.de>
Date:	Wed, 27 Jan 2016 15:04:55 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Arnd Bergmann <arnd@...db.de>, netdev@...r.kernel.org,
	"Maciej W. Rozycki" <macro@...ux-mips.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 5/9] net: fddi/defxx: avoid warning about uninitialized variable use

The defxx driver can be configured for different kinds of buses,
and appears to be handling this correctly, but the compiler cannot
see how it always initializes the bar_start and bar_length
fields it uses depending on the configured bus, so we get a warning
with recent gcc versions:

fddi/defxx.c: In function 'dfx_pci_unregister':
fddi/defxx.c:3726:3: warning: 'bar_len' may be used uninitialized in this function [-Wmaybe-uninitialized]
   release_mem_region(bar_start[0], bar_len[0]);
fddi/defxx.c:3701:18: note: 'bar_len' was declared here
  resource_size_t bar_len[3];  /* resource lengths */
fddi/defxx.c:3726:3: warning: 'bar_start' may be used uninitialized in this function [-Wmaybe-uninitialized]
   release_mem_region(bar_start[0], bar_len[0]);
fddi/defxx.c:3700:18: note: 'bar_start' was declared here
  resource_size_t bar_start[3];  /* pointers to ports */
                  ^
fddi/defxx.c: In function 'dfx_pci_register':
fddi/defxx.c:617:18: warning: 'bar_len' may be used uninitialized in this function [-Wmaybe-uninitialized]
   bp->base.mem = ioremap_nocache(bar_start[0], bar_len[0]);
fddi/defxx.c:537:18: note: 'bar_len' was declared here
  resource_size_t bar_len[3];  /* resource length */
fddi/defxx.c:1125:2: warning: 'bar_start' may be used uninitialized in this function [-Wmaybe-uninitialized]
  pr_info("%s: %s at %s addr = 0x%llx, IRQ = %d, Hardware addr = %pMF\n",
fddi/defxx.c:536:18: note: 'bar_start' was declared here
  resource_size_t bar_start[3];  /* pointers to ports */

This adds code to ensure that the BAR values are initialized
even in the impossible case when a device gets probed that
does not belong to any bus. This shuts up the warning.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/net/fddi/defxx.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/fddi/defxx.c b/drivers/net/fddi/defxx.c
index 7f975a2c8990..e7cdd1226d39 100644
--- a/drivers/net/fddi/defxx.c
+++ b/drivers/net/fddi/defxx.c
@@ -484,6 +484,11 @@ static void dfx_get_bars(struct device *bdev,
 		bar_start[2] = bar_start[1] = 0;
 		bar_len[2] = bar_len[1] = 0;
 	}
+	if (!(dfx_bus_pci || dfx_bus_eisa || dfx_bus_tc)) {
+		dev_err(bdev, "invalid bus configuration\n");
+		bar_start[2] = bar_start[1] = bar_start[0] = 0;
+		bar_len[2] = bar_len[1] = bar_len[0] = 0;
+	}
 }
 
 static const struct net_device_ops dfx_netdev_ops = {
-- 
2.7.0