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Re: [PATCH 22/28] x86: apm: avoid uninitialized data

From Jiri Kosina <jikos@kernel.org>
Newsgroups linux.kernel
Subject Re: [PATCH 22/28] x86: apm: avoid uninitialized data
Date 2016-10-18 15:10 +0200
Message-ID <stCjv-25f-3@gated-at.bofh.it> (permalink)
References <stogy-1lR-13@gated-at.bofh.it> <stozV-1vr-49@gated-at.bofh.it>
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On Tue, 18 Oct 2016, Arnd Bergmann wrote:

> apm_bios_call() can fail, and return a status in its argument
> structure. If that status however is zero during a call from
> apm_get_power_status(), we end up using data that may have
> never been set, as reported by "gcc -Wmaybe-uninitialized":
> 
> arch/x86/kernel/apm_32.c: In function ‘apm’:
> arch/x86/kernel/apm_32.c:1729:17: error: ‘bx’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> arch/x86/kernel/apm_32.c:1835:5: error: ‘cx’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> arch/x86/kernel/apm_32.c:1730:17: note: ‘cx’ was declared here
> arch/x86/kernel/apm_32.c:1842:27: error: ‘dx’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> arch/x86/kernel/apm_32.c:1731:17: note: ‘dx’ was declared here
> 
> This changes the function to return "APM_NO_ERROR" here, which
> makes the code more robust to broken BIOS versions, and avoids
> the warning.
> 
> Cc: x86@kernel.org
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Makes sense.

Reviewed-by: Jiri Kosina <jkosina@suse.cz>

Thanks,

-- 
Jiri Kosina
SUSE Labs

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Thread

[PATCH 00/28] Reenable maybe-uninitialized warnings Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:10 +0200
  [PATCH 08/28] staging: lustre: restore initialization of return code Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
    Re: [lustre-devel] [PATCH 08/28] staging: lustre: restore  initialization of return code Linus Torvalds <torvalds@linux-foundation.org> - 2016-10-18 00:40 +0200
      Re: [lustre-devel] [PATCH 08/28] staging: lustre: restore initialization of return code Arnd Bergmann <arnd@arndb.de> - 2016-10-18 01:10 +0200
    Re: [lustre-devel] [PATCH 08/28] staging: lustre: restore initialization of return code Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:40 +0200
    [PATCH 08/28 v2] staging: lustre: restore initialization of return code Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:50 +0200
  [PATCH 11/28] block: rdb: false-postive gcc-4.9 -Wmaybe-uninitialized Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
    Re: [PATCH 11/28] block: rdb: false-postive gcc-4.9 -Wmaybe-uninitialized Ilya Dryomov <idryomov@gmail.com> - 2016-10-18 12:00 +0200
      Re: [PATCH 11/28] block: rdb: false-postive gcc-4.9 -Wmaybe-uninitialized Arnd Bergmann <arnd@arndb.de> - 2016-10-18 12:10 +0200
  [PATCH 21/28] net/hyperv: avoid uninitialized variable Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
    Re: [PATCH 21/28] net/hyperv: avoid uninitialized variable David Miller <davem@davemloft.net> - 2016-10-18 20:30 +0200
  [PATCH 15/28] crypto: aesni: avoid -Wmaybe-uninitialized warning Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
  [PATCH 19/28] brcmfmac: avoid maybe-uninitialized warning in brcmf_cfg80211_start_ap Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
    Re: [PATCH 19/28] brcmfmac: avoid maybe-uninitialized warning in brcmf_cfg80211_start_ap Kalle Valo <kvalo@codeaurora.org> - 2016-10-26 09:00 +0200
      Re: [PATCH 19/28] brcmfmac: avoid maybe-uninitialized warning in brcmf_cfg80211_start_ap Arnd Bergmann <arnd@arndb.de> - 2016-10-26 12:00 +0200
        Re: [PATCH 19/28] brcmfmac: avoid maybe-uninitialized warning in brcmf_cfg80211_start_ap Kalle Valo <kvalo@codeaurora.org> - 2016-10-26 13:20 +0200
  [PATCH 13/28] [media] dib0700: fix uninitialized data on 'repeat' event Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
  [PATCH 18/28] drm: avoid uninitialized timestamp use in wait_vblank Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
    Re: [PATCH 18/28] drm: avoid uninitialized timestamp use in  wait_vblank Mario Kleiner <mario.kleiner.de@gmail.com> - 2016-10-18 01:50 +0200
      Re: [PATCH 18/28] drm: avoid uninitialized timestamp use in  wait_vblank Daniel Vetter <daniel@ffwll.ch> - 2016-10-18 09:50 +0200
  [PATCH 09/28] staging: lustre: remove broken dead code in cfs_cpt_table_create_pattern Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
  [PATCH 16/28] pcmcia: fix return value of soc_pcmcia_regulator_set Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
    Re: [PATCH 16/28] pcmcia: fix return value of  soc_pcmcia_regulator_set Russell King - ARM Linux <linux@armlinux.org.uk> - 2016-10-18 11:50 +0200
  [PATCH 20/28] net: bcm63xx: avoid referencing uninitialized variable Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
    Re: [PATCH 20/28] net: bcm63xx: avoid referencing uninitialized  variable David Miller <davem@davemloft.net> - 2016-10-18 20:30 +0200
  [PATCH 12/28] [media] rc: print correct variable for z8f0811 Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
  [PATCH 17/28] spi: fsl-espi: avoid processing uninitalized data on error Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
    Re: [PATCH 17/28] spi: fsl-espi: avoid processing uninitalized data  on error Heiner Kallweit <hkallweit1@gmail.com> - 2016-10-24 20:40 +0200
      Re: [PATCH 17/28] spi: fsl-espi: avoid processing uninitalized data  on error Mark Brown <broonie@kernel.org> - 2016-10-24 20:50 +0200
        Re: [PATCH 17/28] spi: fsl-espi: avoid processing uninitalized data on error Arnd Bergmann <arnd@arndb.de> - 2016-10-24 22:40 +0200
          Re: [PATCH 17/28] spi: fsl-espi: avoid processing uninitalized data  on error Mark Brown <broonie@kernel.org> - 2016-10-25 21:20 +0200
            Re: [PATCH 17/28] spi: fsl-espi: avoid processing uninitalized data on error Arnd Bergmann <arnd@arndb.de> - 2016-10-25 23:00 +0200
    Re: [PATCH 17/28] spi: fsl-espi: avoid processing uninitalized data  on error Mark Brown <broonie@kernel.org> - 2016-10-24 21:00 +0200
    Applied "spi: fsl-espi: avoid processing uninitalized data on error" to the spi tree Mark Brown <broonie@kernel.org> - 2016-10-26 12:30 +0200
      Merge problem: Re: Applied "spi: fsl-espi: avoid processing  uninitalized data on error" to the spi tree Heiner Kallweit <hkallweit1@gmail.com> - 2016-10-26 20:20 +0200
        Re: Merge problem: Re: Applied "spi: fsl-espi: avoid processing  uninitalized data on error" to the spi tree Mark Brown <broonie@kernel.org> - 2016-10-27 00:00 +0200
  [PATCH 10/28] UBI: fix uninitialized access of vid_hdr pointer Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
    Re: [PATCH 10/28] UBI: fix uninitialized access of vid_hdr pointer Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-10-18 07:20 +0200
  [PATCH 14/28] iio: accel: sca3000_core: avoid potentially uninitialized variable Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:20 +0200
    Re: [PATCH 14/28] iio: accel: sca3000_core: avoid potentially  uninitialized variable Jonathan Cameron <jic23@kernel.org> - 2016-10-23 23:30 +0200
  [PATCH 24/28] x86: math-emu: possible uninitialized variable use Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:30 +0200
  [PATCH 22/28] x86: apm: avoid uninitialized data Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:30 +0200
    Re: [PATCH 22/28] x86: apm: avoid uninitialized data Jiri Kosina <jikos@kernel.org> - 2016-10-18 15:10 +0200
    Re: [PATCH 22/28] x86: apm: avoid uninitialized data "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-10-18 23:40 +0200
  [PATCH 27/28] rocker: fix maybe-uninitialized warning Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:30 +0200
    Re: [PATCH 27/28] rocker: fix maybe-uninitialized warning David Miller <davem@davemloft.net> - 2016-10-18 20:30 +0200
  [PATCH 26/28] nios2: fix timer initcall return value Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:30 +0200
    Re: [PATCH 26/28] nios2: fix timer initcall return value Ley Foon Tan <lftan@altera.com> - 2016-10-24 03:00 +0200
  [PATCH 25/28] s390: pci: don't print uninitialized data for debugging Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:30 +0200
    Re: [PATCH 25/28] s390: pci: don't print uninitialized data for  debugging Martin Schwidefsky <schwidefsky@de.ibm.com> - 2016-10-18 09:00 +0200
      Re: [PATCH 25/28] s390: pci: don't print uninitialized data for  debugging Sebastian Ott <sebott@linux.vnet.ibm.com> - 2016-10-18 11:00 +0200
  [PATCH 23/28] x86: mark target address as output in 'insb' asm Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:30 +0200
  [PATCH 28/28] Kbuild: bring back -Wmaybe-uninitialized warning Arnd Bergmann <arnd@arndb.de> - 2016-10-18 00:30 +0200
  Re: [PATCH 00/28] Reenable maybe-uninitialized warnings Christoph Hellwig <hch@infradead.org> - 2016-10-18 07:10 +0200

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