| Message ID | 1441790182-20248-1-git-send-email-Yuantian.Tang@freescale.com |
|---|---|
| State | Not Applicable |
| Delegated to: | David Miller |
| Headers | show |
Hi, On 09-09-15 11:16, Yuantian.Tang@freescale.com wrote: > From: Tang Yuantian <Yuantian.Tang@freescale.com> > > kbuild test robot reports the warnings: > drivers/ata/ahci_qoriq.c: In function 'ahci_qoriq_hardreset': >>> include/asm-generic/io.h:163:2: warning: 'px_is' may be used >>> uninitialized in this function [-Wuninitialized] > drivers/ata/ahci_qoriq.c:70:14: note: 'px_is' was declared here >>> include/asm-generic/io.h:163:2: warning: 'px_cmd' may be used >>> uninitialized in this function [-Wuninitialized] > drivers/ata/ahci_qoriq.c:70:6: note: 'px_cmd' was declared here > > This patch fixed it by assigning 0 to px_is and px_cmd variables. > This patch also remove line 'struct ccsr_ahci *reg_base' which is > not referred by any other codes and thus a dead one. > > Signed-off-by: Tang Yuantian <Yuantian.Tang@freescale.com> LGTM: Acked-by: Hans de Goede <hdegoede@redhat.com> Regards, Hans > --- > drivers/ata/ahci_qoriq.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/ata/ahci_qoriq.c b/drivers/ata/ahci_qoriq.c > index e5e4988..f790852 100644 > --- a/drivers/ata/ahci_qoriq.c > +++ b/drivers/ata/ahci_qoriq.c > @@ -49,7 +49,6 @@ enum ahci_qoriq_type { > }; > > struct ahci_qoriq_priv { > - struct ccsr_ahci *reg_base; > enum ahci_qoriq_type type; > void __iomem *ecc_addr; > }; > @@ -67,7 +66,7 @@ static int ahci_qoriq_hardreset(struct ata_link *link, unsigned int *class, > { > const unsigned long *timing = sata_ehc_deb_timing(&link->eh_context); > void __iomem *port_mmio = ahci_port_base(link->ap); > - u32 px_cmd, px_is, px_val; > + u32 px_cmd = 0, px_is = 0, px_val; > struct ata_port *ap = link->ap; > struct ahci_port_priv *pp = ap->private_data; > struct ahci_host_priv *hpriv = ap->host->private_data; > -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, Sep 09, 2015 at 05:16:22PM +0800, Yuantian.Tang@freescale.com wrote: > From: Tang Yuantian <Yuantian.Tang@freescale.com> > > kbuild test robot reports the warnings: > drivers/ata/ahci_qoriq.c: In function 'ahci_qoriq_hardreset': > >> include/asm-generic/io.h:163:2: warning: 'px_is' may be used > >> uninitialized in this function [-Wuninitialized] > drivers/ata/ahci_qoriq.c:70:14: note: 'px_is' was declared here > >> include/asm-generic/io.h:163:2: warning: 'px_cmd' may be used > >> uninitialized in this function [-Wuninitialized] > drivers/ata/ahci_qoriq.c:70:6: note: 'px_cmd' was declared here > > This patch fixed it by assigning 0 to px_is and px_cmd variables. > This patch also remove line 'struct ccsr_ahci *reg_base' which is > not referred by any other codes and thus a dead one. Hmm... I think the problem here is that the complier can't know whether qoriq_priv->type would change across intervening function calls. Maybe a better solution is caching the type in a local variable so that the compiler can tell that those two tests will always move together? It generally isn't a good idea to clear variables unnecessarily as that can hide actual bugs that compiler can detect. Thanks.
> -----Original Message----- > From: Tejun Heo [mailto:htejun@gmail.com] On Behalf Of Tejun Heo > Sent: Wednesday, September 09, 2015 10:02 PM > To: Tang Yuantian-B29983 <Yuantian.Tang@freescale.com> > Cc: hdegoede@redhat.com; linux-ide@vger.kernel.org; linux- > kernel@vger.kernel.org; devicetree@vger.kernel.org > Subject: Re: [PATCH] ahci: qoriq: fixed using uninitialized variable warnings > > On Wed, Sep 09, 2015 at 05:16:22PM +0800, Yuantian.Tang@freescale.com > wrote: > > From: Tang Yuantian <Yuantian.Tang@freescale.com> > > > > kbuild test robot reports the warnings: > > drivers/ata/ahci_qoriq.c: In function 'ahci_qoriq_hardreset': > > >> include/asm-generic/io.h:163:2: warning: 'px_is' may be used > > >> uninitialized in this function [-Wuninitialized] > > drivers/ata/ahci_qoriq.c:70:14: note: 'px_is' was declared here > > >> include/asm-generic/io.h:163:2: warning: 'px_cmd' may be used > > >> uninitialized in this function [-Wuninitialized] > > drivers/ata/ahci_qoriq.c:70:6: note: 'px_cmd' was declared here > > > > This patch fixed it by assigning 0 to px_is and px_cmd variables. > > This patch also remove line 'struct ccsr_ahci *reg_base' which is not > > referred by any other codes and thus a dead one. > > Hmm... I think the problem here is that the complier can't know whether > qoriq_priv->type would change across intervening function calls. Maybe a > better solution is caching the type in a local variable so that the compiler can > tell that those two tests will always move together? It generally isn't a good > idea to clear variables unnecessarily as that can hide actual bugs that compiler > can detect. > I am not sure if the warning can be removed this way. But I will send the patch as your suggestion. Unfortunately, I can't produce this warning no matter if I add -Wuninitialized. So please let me know if the new patch is working. Regards, Yuantian > Thanks. > > -- > tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Tejun, Could you please take the version 1 patch? The version 2 patch can't address these warnings, and the version 1 can definitely remove them. In this case, that would cause any hidden bugs, so no worries. Regards, Yuantian > -----Original Message----- > From: Tejun Heo [mailto:htejun@gmail.com] On Behalf Of Tejun Heo > Sent: Wednesday, September 09, 2015 10:02 PM > To: Tang Yuantian-B29983 <Yuantian.Tang@freescale.com> > Cc: hdegoede@redhat.com; linux-ide@vger.kernel.org; linux- > kernel@vger.kernel.org; devicetree@vger.kernel.org > Subject: Re: [PATCH] ahci: qoriq: fixed using uninitialized variable warnings > > On Wed, Sep 09, 2015 at 05:16:22PM +0800, Yuantian.Tang@freescale.com > wrote: > > From: Tang Yuantian <Yuantian.Tang@freescale.com> > > > > kbuild test robot reports the warnings: > > drivers/ata/ahci_qoriq.c: In function 'ahci_qoriq_hardreset': > > >> include/asm-generic/io.h:163:2: warning: 'px_is' may be used > > >> uninitialized in this function [-Wuninitialized] > > drivers/ata/ahci_qoriq.c:70:14: note: 'px_is' was declared here > > >> include/asm-generic/io.h:163:2: warning: 'px_cmd' may be used > > >> uninitialized in this function [-Wuninitialized] > > drivers/ata/ahci_qoriq.c:70:6: note: 'px_cmd' was declared here > > > > This patch fixed it by assigning 0 to px_is and px_cmd variables. > > This patch also remove line 'struct ccsr_ahci *reg_base' which is not > > referred by any other codes and thus a dead one. > > Hmm... I think the problem here is that the complier can't know whether > qoriq_priv->type would change across intervening function calls. Maybe a > better solution is caching the type in a local variable so that the compiler can > tell that those two tests will always move together? It generally isn't a good > idea to clear variables unnecessarily as that can hide actual bugs that compiler > can detect. > > Thanks. > > -- > tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hello, Yuantian. On Fri, Sep 11, 2015 at 05:27:25AM +0000, Yuantian Tang wrote: > Hi Tejun, > > Could you please take the version 1 patch? > The version 2 patch can't address these warnings, and the version 1 can definitely remove them. > In this case, that would cause any hidden bugs, so no worries. Ugh... I really hate changes which are made to just work around compiler silliness. If this is something which goes away with newer gcc, Fengguang can just make it as a known false positive. Yuantian, which compiler are you using? Thanks.
Hello Tejun, The toolchain I used is: gcc version 4.8.3 20140401 (prerelease) (Linaro GCC 4.8-2014.04) I have not found this warning using this tool chain with -Wuninitialized flag. Regards, Yuantian > -----Original Message----- > From: Tejun Heo [mailto:htejun@gmail.com] On Behalf Of Tejun Heo > Sent: Friday, September 11, 2015 9:55 PM > To: Tang Yuantian-B29983 <Yuantian.Tang@freescale.com> > Cc: hdegoede@redhat.com; linux-ide@vger.kernel.org; linux- > kernel@vger.kernel.org; devicetree@vger.kernel.org; Fengguang Wu > <fengguang.wu@intel.com> > Subject: Re: [PATCH] ahci: qoriq: fixed using uninitialized variable warnings > > Hello, Yuantian. > > On Fri, Sep 11, 2015 at 05:27:25AM +0000, Yuantian Tang wrote: > > Hi Tejun, > > > > Could you please take the version 1 patch? > > The version 2 patch can't address these warnings, and the version 1 can > definitely remove them. > > In this case, that would cause any hidden bugs, so no worries. > > Ugh... I really hate changes which are made to just work around compiler > silliness. If this is something which goes away with newer gcc, Fengguang can > just make it as a known false positive. Yuantian, which compiler are you > using? > > Thanks. > > -- > tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Yuantian, It's cross compiling on ARCH=openrisc. Thanks, Fengguang On Mon, Sep 14, 2015 at 03:02:27AM +0000, Yuantian Tang wrote: > Hello Tejun, > > The toolchain I used is: > gcc version 4.8.3 20140401 (prerelease) (Linaro GCC 4.8-2014.04) > > I have not found this warning using this tool chain with -Wuninitialized flag. > > Regards, > Yuantian > > > -----Original Message----- > > From: Tejun Heo [mailto:htejun@gmail.com] On Behalf Of Tejun Heo > > Sent: Friday, September 11, 2015 9:55 PM > > To: Tang Yuantian-B29983 <Yuantian.Tang@freescale.com> > > Cc: hdegoede@redhat.com; linux-ide@vger.kernel.org; linux- > > kernel@vger.kernel.org; devicetree@vger.kernel.org; Fengguang Wu > > <fengguang.wu@intel.com> > > Subject: Re: [PATCH] ahci: qoriq: fixed using uninitialized variable warnings > > > > Hello, Yuantian. > > > > On Fri, Sep 11, 2015 at 05:27:25AM +0000, Yuantian Tang wrote: > > > Hi Tejun, > > > > > > Could you please take the version 1 patch? > > > The version 2 patch can't address these warnings, and the version 1 can > > definitely remove them. > > > In this case, that would cause any hidden bugs, so no worries. > > > > Ugh... I really hate changes which are made to just work around compiler > > silliness. If this is something which goes away with newer gcc, Fengguang can > > just make it as a known false positive. Yuantian, which compiler are you > > using? > > > > Thanks. > > > > -- > > tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
The ARCH should have been ARM for this driver. Do you think this warning would go away if adding a dependency on ARM? Regards, Yuantian > -----Original Message----- > From: Fengguang Wu [mailto:fengguang.wu@intel.com] > Sent: Monday, September 14, 2015 12:05 PM > To: Tang Yuantian-B29983 <Yuantian.Tang@freescale.com> > Cc: Tejun Heo <tj@kernel.org>; hdegoede@redhat.com; linux- > ide@vger.kernel.org; linux-kernel@vger.kernel.org; > devicetree@vger.kernel.org > Subject: Re: [PATCH] ahci: qoriq: fixed using uninitialized variable warnings > > Yuantian, > > It's cross compiling on ARCH=openrisc. > > Thanks, > Fengguang > > On Mon, Sep 14, 2015 at 03:02:27AM +0000, Yuantian Tang wrote: > > Hello Tejun, > > > > The toolchain I used is: > > gcc version 4.8.3 20140401 (prerelease) (Linaro GCC 4.8-2014.04) > > > > I have not found this warning using this tool chain with -Wuninitialized flag. > > > > Regards, > > Yuantian > > > > > -----Original Message----- > > > From: Tejun Heo [mailto:htejun@gmail.com] On Behalf Of Tejun Heo > > > Sent: Friday, September 11, 2015 9:55 PM > > > To: Tang Yuantian-B29983 <Yuantian.Tang@freescale.com> > > > Cc: hdegoede@redhat.com; linux-ide@vger.kernel.org; linux- > > > kernel@vger.kernel.org; devicetree@vger.kernel.org; Fengguang Wu > > > <fengguang.wu@intel.com> > > > Subject: Re: [PATCH] ahci: qoriq: fixed using uninitialized variable > > > warnings > > > > > > Hello, Yuantian. > > > > > > On Fri, Sep 11, 2015 at 05:27:25AM +0000, Yuantian Tang wrote: > > > > Hi Tejun, > > > > > > > > Could you please take the version 1 patch? > > > > The version 2 patch can't address these warnings, and the version > > > > 1 can > > > definitely remove them. > > > > In this case, that would cause any hidden bugs, so no worries. > > > > > > Ugh... I really hate changes which are made to just work around > > > compiler silliness. If this is something which goes away with newer > > > gcc, Fengguang can just make it as a known false positive. > > > Yuantian, which compiler are you using? > > > > > > Thanks. > > > > > > -- > > > tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Sep 14, 2015 at 06:51:36AM +0000, Yuantian Tang wrote: > The ARCH should have been ARM for this driver. > Do you think this warning would go away if adding a dependency on ARM? Yes, that may work. Thanks, Fengguang > > -----Original Message----- > > From: Fengguang Wu [mailto:fengguang.wu@intel.com] > > Sent: Monday, September 14, 2015 12:05 PM > > To: Tang Yuantian-B29983 <Yuantian.Tang@freescale.com> > > Cc: Tejun Heo <tj@kernel.org>; hdegoede@redhat.com; linux- > > ide@vger.kernel.org; linux-kernel@vger.kernel.org; > > devicetree@vger.kernel.org > > Subject: Re: [PATCH] ahci: qoriq: fixed using uninitialized variable warnings > > > > Yuantian, > > > > It's cross compiling on ARCH=openrisc. > > > > Thanks, > > Fengguang > > > > On Mon, Sep 14, 2015 at 03:02:27AM +0000, Yuantian Tang wrote: > > > Hello Tejun, > > > > > > The toolchain I used is: > > > gcc version 4.8.3 20140401 (prerelease) (Linaro GCC 4.8-2014.04) > > > > > > I have not found this warning using this tool chain with -Wuninitialized flag. > > > > > > Regards, > > > Yuantian > > > > > > > -----Original Message----- > > > > From: Tejun Heo [mailto:htejun@gmail.com] On Behalf Of Tejun Heo > > > > Sent: Friday, September 11, 2015 9:55 PM > > > > To: Tang Yuantian-B29983 <Yuantian.Tang@freescale.com> > > > > Cc: hdegoede@redhat.com; linux-ide@vger.kernel.org; linux- > > > > kernel@vger.kernel.org; devicetree@vger.kernel.org; Fengguang Wu > > > > <fengguang.wu@intel.com> > > > > Subject: Re: [PATCH] ahci: qoriq: fixed using uninitialized variable > > > > warnings > > > > > > > > Hello, Yuantian. > > > > > > > > On Fri, Sep 11, 2015 at 05:27:25AM +0000, Yuantian Tang wrote: > > > > > Hi Tejun, > > > > > > > > > > Could you please take the version 1 patch? > > > > > The version 2 patch can't address these warnings, and the version > > > > > 1 can > > > > definitely remove them. > > > > > In this case, that would cause any hidden bugs, so no worries. > > > > > > > > Ugh... I really hate changes which are made to just work around > > > > compiler silliness. If this is something which goes away with newer > > > > gcc, Fengguang can just make it as a known false positive. > > > > Yuantian, which compiler are you using? > > > > > > > > Thanks. > > > > > > > > -- > > > > tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/ata/ahci_qoriq.c b/drivers/ata/ahci_qoriq.c index e5e4988..f790852 100644 --- a/drivers/ata/ahci_qoriq.c +++ b/drivers/ata/ahci_qoriq.c @@ -49,7 +49,6 @@ enum ahci_qoriq_type { }; struct ahci_qoriq_priv { - struct ccsr_ahci *reg_base; enum ahci_qoriq_type type; void __iomem *ecc_addr; }; @@ -67,7 +66,7 @@ static int ahci_qoriq_hardreset(struct ata_link *link, unsigned int *class, { const unsigned long *timing = sata_ehc_deb_timing(&link->eh_context); void __iomem *port_mmio = ahci_port_base(link->ap); - u32 px_cmd, px_is, px_val; + u32 px_cmd = 0, px_is = 0, px_val; struct ata_port *ap = link->ap; struct ahci_port_priv *pp = ap->private_data; struct ahci_host_priv *hpriv = ap->host->private_data;