From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Sebastian Ott <sebott@linux.vnet.ibm.com>,
Gerald Schaefer <gerald.schaefer@de.ibm.com>,
Joerg Roedel <jroedel@suse.de>,
Christian Borntraeger <borntraeger@de.ibm.com>,
linux-s390@vger.kernel.org
Subject: Re: [PATCH 25/28] s390: pci: don't print uninitialized data for debugging
Date: Tue, 18 Oct 2016 08:48:55 +0200 [thread overview]
Message-ID: <20161018084855.1a100670@mschwide> (raw)
In-Reply-To: <20161017221650.1902729-6-arnd@arndb.de>
On Tue, 18 Oct 2016 00:16:13 +0200
Arnd Bergmann <arnd@arndb.de> wrote:
> 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@arndb.de>
> ---
> 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);
The compiler is right. pa is set in the for-loop. If "dma_addr < dma_addr_base + size"
is never true and __dma_purge_tlb() returns with an error, pa *is* uninitialized.
The fix seems sensible to me.
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
next prev parent reply other threads:[~2016-10-18 6:49 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-17 22:03 [PATCH 00/28] Reenable maybe-uninitialized warnings Arnd Bergmann
2016-10-17 22:05 ` [PATCH 01/28] [v2] netfilter: nf_tables: avoid uninitialized variable warning Arnd Bergmann
2016-10-18 15:23 ` Pablo Neira Ayuso
2016-10-17 22:05 ` [PATCH 02/28] [v2] mtd: mtk: avoid warning in mtk_ecc_encode Arnd Bergmann
2016-10-18 5:19 ` Boris Brezillon
[not found] ` <1476785552.24626.4.camel@mtkswgap22>
2016-10-18 19:45 ` Boris Brezillon
2016-10-17 22:05 ` [PATCH 03/28] [v2] infiniband: shut up a maybe-uninitialized warning Arnd Bergmann
2016-10-18 6:47 ` Haggai Eran
2016-10-18 10:18 ` Arnd Bergmann
2016-10-18 10:32 ` Haggai Eran
2016-10-17 22:05 ` [PATCH 04/28] f2fs: replace a build-time warning with runtime WARN_ON Arnd Bergmann
2016-10-26 14:05 ` [f2fs-dev] " Chao Yu
2016-10-26 14:57 ` Arnd Bergmann
2016-10-27 11:41 ` Chao Yu
2016-10-17 22:05 ` [PATCH 05/28] ext2: avoid bogus -Wmaybe-uninitialized warning Arnd Bergmann
2016-10-18 5:15 ` Christoph Hellwig
2016-10-18 9:30 ` Jan Kara
2016-10-17 22:05 ` [PATCH 06/28] NFSv4.1: work around " Arnd Bergmann
2016-10-17 22:08 ` [PATCH 07/28] ceph: avoid false positive maybe-uninitialized warning Arnd Bergmann
2016-10-18 2:07 ` Yan, Zheng
2016-10-17 22:08 ` [PATCH 08/28] staging: lustre: restore initialization of return code Arnd Bergmann
[not found] ` <CY4PR11MB1751050A7C7AF840E94DDE60CBD00@CY4PR11MB1751.namprd11.prod.outlook.com>
2016-10-17 22:29 ` [lustre-devel] " Arnd Bergmann
2016-10-17 22:37 ` Linus Torvalds
2016-10-17 23:00 ` Arnd Bergmann
2016-10-17 22:42 ` [PATCH 08/28 v2] " Arnd Bergmann
2016-10-17 22:08 ` [PATCH 09/28] staging: lustre: remove broken dead code in cfs_cpt_table_create_pattern Arnd Bergmann
2016-10-17 22:10 ` [PATCH 10/28] UBI: fix uninitialized access of vid_hdr pointer Arnd Bergmann
2016-10-18 5:17 ` Boris Brezillon
2016-10-17 22:10 ` [PATCH 11/28] block: rdb: false-postive gcc-4.9 -Wmaybe-uninitialized Arnd Bergmann
2016-10-18 9:57 ` Ilya Dryomov
2016-10-18 10:04 ` Arnd Bergmann
2016-10-17 22:12 ` [PATCH 12/28] [media] rc: print correct variable for z8f0811 Arnd Bergmann
2016-10-17 22:13 ` [PATCH 13/28] [media] dib0700: fix uninitialized data on 'repeat' event Arnd Bergmann
2016-10-17 22:13 ` [PATCH 14/28] iio: accel: sca3000_core: avoid potentially uninitialized variable Arnd Bergmann
2016-10-23 21:25 ` Jonathan Cameron
2016-10-17 22:13 ` [PATCH 15/28] crypto: aesni: avoid -Wmaybe-uninitialized warning Arnd Bergmann
2016-10-17 22:13 ` [PATCH 16/28] pcmcia: fix return value of soc_pcmcia_regulator_set Arnd Bergmann
2016-10-18 9:42 ` Russell King - ARM Linux
2016-10-17 22:13 ` [PATCH 17/28] spi: fsl-espi: avoid processing uninitalized data on error Arnd Bergmann
2016-10-24 17:27 ` Mark Brown
2016-10-24 18:36 ` Heiner Kallweit
2016-10-24 18:45 ` Mark Brown
2016-10-24 20:37 ` Arnd Bergmann
2016-10-25 19:13 ` Mark Brown
2016-10-25 20:57 ` Arnd Bergmann
2016-10-26 10:15 ` Applied "spi: fsl-espi: avoid processing uninitalized data on error" to the spi tree Mark Brown
2016-10-26 18:11 ` Merge problem: " Heiner Kallweit
2016-10-26 21:59 ` Mark Brown
2016-10-17 22:13 ` [PATCH 18/28] drm: avoid uninitialized timestamp use in wait_vblank Arnd Bergmann
2016-10-17 23:47 ` Mario Kleiner
2016-10-18 7:46 ` Daniel Vetter
2016-10-17 22:13 ` [PATCH 19/28] brcmfmac: avoid maybe-uninitialized warning in brcmf_cfg80211_start_ap Arnd Bergmann
2016-10-26 6:49 ` Kalle Valo
2016-10-26 9:57 ` Arnd Bergmann
2016-10-26 11:11 ` Kalle Valo
2016-10-27 15:05 ` [19/28] " Kalle Valo
2016-10-17 22:16 ` [PATCH 20/28] net: bcm63xx: avoid referencing uninitialized variable Arnd Bergmann
2016-10-18 18:21 ` David Miller
2016-10-17 22:16 ` [PATCH 21/28] net/hyperv: avoid " Arnd Bergmann
2016-10-18 18:21 ` David Miller
2016-10-17 22:16 ` [PATCH 22/28] x86: apm: avoid uninitialized data Arnd Bergmann
2016-10-18 13:05 ` Jiri Kosina
2016-10-18 21:35 ` Luis R. Rodriguez
2016-10-17 22:16 ` [PATCH 23/28] x86: mark target address as output in 'insb' asm Arnd Bergmann
2016-10-17 22:16 ` [PATCH 24/28] x86: math-emu: possible uninitialized variable use Arnd Bergmann
2016-10-17 22:16 ` [PATCH 25/28] s390: pci: don't print uninitialized data for debugging Arnd Bergmann
2016-10-18 6:48 ` Martin Schwidefsky [this message]
2016-10-18 8:53 ` Sebastian Ott
2016-10-17 22:16 ` [PATCH 26/28] nios2: fix timer initcall return value Arnd Bergmann
2016-10-24 0:54 ` Ley Foon Tan
2016-10-17 22:16 ` [PATCH 27/28] rocker: fix maybe-uninitialized warning Arnd Bergmann
2016-10-18 18:21 ` David Miller
2016-10-17 22:19 ` [PATCH 28/28] Kbuild: bring back -Wmaybe-uninitialized warning Arnd Bergmann
2016-10-18 5:08 ` [PATCH 00/28] Reenable maybe-uninitialized warnings Christoph Hellwig
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