linux-kernel - [PATCH v2 05/11] s390: pci: don't print uninitialized data for debugging

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Message-Id: <20161110164454.293477-6-arnd@arndb.de>
Date:   Thu, 10 Nov 2016 17:44:48 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Anna Schumaker <anna.schumaker@...app.com>,
        "David S. Miller" <davem@...emloft.net>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Ilya Dryomov <idryomov@...il.com>,
        Javier Martinez Canillas <javier@....samsung.com>,
        Jiri Kosina <jikos@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Ley Foon Tan <lftan@...era.com>,
        "Luis R . Rodriguez" <mcgrof@...nel.org>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Michal Marek <mmarek@...e.com>,
        Russell King <linux@...linux.org.uk>,
        Sean Young <sean@...s.org>,
        Sebastian Ott <sebott@...ux.vnet.ibm.com>,
        Trond Myklebust <trond.myklebust@...marydata.com>,
        x86@...nel.org, linux-kbuild@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-snps-arc@...ts.infradead.org,
        nios2-dev@...ts.rocketboards.org, linux-s390@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-media@...r.kernel.org,
        linux-nfs@...r.kernel.org
Subject: [PATCH v2 05/11] s390: pci: don't print uninitialized data for debugging

gcc correctly warns about an incorrect use of the 'pa' variable
in case we pass an empty scatterlist to __s390_dma_map_sg:

arch/s390/pci/pci_dma.c: In function '__s390_dma_map_sg':
arch/s390/pci/pci_dma.c:309:13: warning: 'pa' may be used uninitialized in this function [-Wmaybe-uninitialized]

This adds a bogus initialization to the function to sanitize
the debug output.  I would have preferred a solution without
the initialization, but I only got the report from the
kbuild bot after turning on the warning again, and didn't
manage to reproduce it myself.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Acked-by: Sebastian Ott <sebott@...ux.vnet.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@...ibm.com>
---
 arch/s390/pci/pci_dma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
index 7350c8b..6b2f72f 100644
--- a/arch/s390/pci/pci_dma.c
+++ b/arch/s390/pci/pci_dma.c
@@ -423,7 +423,7 @@ static int __s390_dma_map_sg(struct device *dev, struct scatterlist *sg,
 	dma_addr_t dma_addr_base, dma_addr;
 	int flags = ZPCI_PTE_VALID;
 	struct scatterlist *s;
-	unsigned long pa;
+	unsigned long pa = 0;
 	int ret;
 
 	size = PAGE_ALIGN(size);
-- 
2.9.0