[BUG] stable-4.4: xen/tools/blktap2/drivers/block-qcow.c build errors

[BUG] stable-4.4: xen/tools/blktap2/drivers/block-qcow.c build errors

[Leonardo Taccari]

Hello to the entire Xen community,
trying to build Xen ARM on Debian GNU/Linux armhf testing gives the
following errors (doing a "./configure && make dist-tools"):

[...]
gcc  -O1 -fno-omit-frame-pointer -marm -g -fno-strict-aliasing -std=gnu99 -Wall -Wstrict-prototypes -
Wdeclaration-after-statement -Wno-unused-but-set-variable -Wno-unused-local-typedefs   -D__XEN_TOOLS_
_ -MMD -MF .block-qcow.o.d -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -fno-opti
mize-sibling-calls  -Werror -g -Wno-unused -fno-strict-aliasing -I../include -I../drivers -I/root/xen
/tools/blktap2/drivers/../../../tools/libxc -I/root/xen/tools/blktap2/drivers/../../../tools/include 
-D_GNU_SOURCE -DUSE_NFS_LOCKS  -c -o block-qcow.o block-qcow.c 
block-qcow.c: In function 'get_cluster_offset':
block-qcow.c:431:3: error: 'tmp_ptr' may be used uninitialized in this function [-Werror=maybe-uninit
ialized]
   memcpy(tmp_ptr, l1_ptr, 4096);
   ^
block-qcow.c:606:7: error: 'tmp_ptr2' may be used uninitialized in this function [-Werror=maybe-unini
tialized]
   if (write(s->fd, tmp_ptr2, 4096) != 4096) {
       ^
cc1: all warnings being treated as errors
/root/xen/tools/blktap2/drivers/../../../tools/Rules.mk:89: recipe for target 'block-qcow.o' failed
make[5]: *** [block-qcow.o] Error 1
make[5]: Leaving directory '/root/xen/tools/blktap2/drivers'
/root/xen/tools/blktap2/../../tools/Rules.mk:105: recipe for target 'subdir-install-drivers' failed
make[4]: *** [subdir-install-drivers] Error 2
make[4]: Leaving directory '/root/xen/tools/blktap2'
/root/xen/tools/blktap2/../../tools/Rules.mk:100: recipe for target 'subdirs-install' failed
make[3]: *** [subdirs-install] Error 2
make[3]: Leaving directory '/root/xen/tools/blktap2'
/root/xen/tools/../tools/Rules.mk:105: recipe for target 'subdir-install-blktap2' failed
make[2]: *** [subdir-install-blktap2] Error 2
make[2]: Leaving directory '/root/xen/tools'
/root/xen/tools/../tools/Rules.mk:100: recipe for target 'subdirs-install' failed
make[1]: *** [subdirs-install] Error 2
make[1]: Leaving directory '/root/xen/tools'
Makefile:96: recipe for target 'install-tools' failed
make: *** [install-tools] Error 2
[...]

Unfortunately I'm not an expert C programmer but after reading
posix_memalign(3) it seems that the compiler warning is right.
Removing -Werror on the affected file fix this issue but it's just a
workaround.

For more information about the compiler:
$ gcc -v
Using built-in specs.
COLLECT_GCC=/usr/bin/gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/arm-linux-gnueabihf/4.9/lto-wrapper
Target: arm-linux-gnueabihf
Configured with: ../src/configure -v --with-pkgversion='Debian 4.9.0-7' --with-bugurl=file:///usr/share/doc/gcc-4.9/README.Bugs --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.9 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.9 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-libmudflap --disable-libitm --disable-libquadmath --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.9-armhf/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/ja
 va-1.5.0-gcj-4.9-armhf --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.9-armhf --with-arch-directory=arm --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-sjlj-exceptions --with-arch=armv7-a --with-fpu=vfpv3-d16 --with-float=hard --with-mode=thumb --enable-checking=release --build=arm-linux-gnueabihf --host=arm-linux-gnueabihf --target=arm-linux-gnueabihf
Thread model: posix
gcc version 4.9.0 (Debian 4.9.0-7) 

If you need more information about my environment don't hesitate to
contact me!
I've succesfully built the stable-4.4 branch about one month ago and
succesfully run it on a cubieboard2.


Thanks for your consideration,
Ciao,
L.

Re: [BUG] stable-4.4: xen/tools/blktap2/drivers/block-qcow.c build errors

[Ian Campbell]

On Mon, 2014-06-30 at 18:59 +0200, Leonardo Taccari wrote:
> Hello to the entire Xen community,
> trying to build Xen ARM on Debian GNU/Linux armhf testing gives the
> following errors (doing a "./configure && make dist-tools"):
> 
> [...]
> gcc  -O1 -fno-omit-frame-pointer -marm -g -fno-strict-aliasing -std=gnu99 -Wall -Wstrict-prototypes -
> Wdeclaration-after-statement -Wno-unused-but-set-variable -Wno-unused-local-typedefs   -D__XEN_TOOLS_
> _ -MMD -MF .block-qcow.o.d -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -fno-opti
> mize-sibling-calls  -Werror -g -Wno-unused -fno-strict-aliasing -I../include -I../drivers -I/root/xen
> /tools/blktap2/drivers/../../../tools/libxc -I/root/xen/tools/blktap2/drivers/../../../tools/include 
> -D_GNU_SOURCE -DUSE_NFS_LOCKS  -c -o block-qcow.o block-qcow.c 
> block-qcow.c: In function 'get_cluster_offset':
> block-qcow.c:431:3: error: 'tmp_ptr' may be used uninitialized in this function [-Werror=maybe-uninit
> ialized]
>    memcpy(tmp_ptr, l1_ptr, 4096);
>    ^
> block-qcow.c:606:7: error: 'tmp_ptr2' may be used uninitialized in this function [-Werror=maybe-unini
> tialized]
>    if (write(s->fd, tmp_ptr2, 4096) != 4096) {
>        ^

Thanks for the report.

This was fixed in master with
commit 345e44a85d71a1a910385f33c7f1ba3683026d18
Author: Dario Faggioli <dario.faggioli@citrix.com>
Date:   Fri Jun 20 16:09:00 2014 +0200

    blktap2: Fix two 'maybe uninitialized' variables
 
I think this should already be on Ian's list for eventual backport to
4.4, but I've copied him to make sure.

Ian.

Re: [BUG] stable-4.4: xen/tools/blktap2/drivers/block-qcow.c build errors

[Ian Jackson]

Ian Campbell writes ("Re: [Xen-devel] [BUG] stable-4.4: xen/tools/blktap2/drivers/block-qcow.c build errors"):
> This was fixed in master with
> commit 345e44a85d71a1a910385f33c7f1ba3683026d18
> Author: Dario Faggioli <dario.faggioli@citrix.com>
> Date:   Fri Jun 20 16:09:00 2014 +0200
> 
>     blktap2: Fix two 'maybe uninitialized' variables
>  
> I think this should already be on Ian's list for eventual backport to
> 4.4, but I've copied him to make sure.

It is indeed.

Thanks,
Ian.

Re: [BUG] stable-4.4: xen/tools/blktap2/drivers/block-qcow.c build errors

[Leonardo Taccari]

Hello,

On Wed, Jul 02, 2014 at 12:49:50PM +0100, Ian Jackson wrote:
> Ian Campbell writes ("Re: [Xen-devel] [BUG] stable-4.4: xen/tools/blktap2/drivers/block-qcow.c build errors"):
> > This was fixed in master with
> > commit 345e44a85d71a1a910385f33c7f1ba3683026d18
> > Author: Dario Faggioli <dario.faggioli@citrix.com>
> > Date:   Fri Jun 20 16:09:00 2014 +0200
> > 
> >     blktap2: Fix two 'maybe uninitialized' variables
> >  
> > I think this should already be on Ian's list for eventual backport to
> > 4.4, but I've copied him to make sure.
> 
> It is indeed.
I've compiled-tested it (manually applied the patch in 4.4) and I can
confirm that now the errors are gone away.


Thank you and keep up the good work!
L.

Re: [BUG] stable-4.4: xen/tools/blktap2/drivers/block-qcow.c build errors

[Leonardo Taccari]

On Mon, Jun 30, 2014 at 06:59:42PM +0200, Leonardo Taccari wrote:
> [...]
> gcc  -O1 -fno-omit-frame-pointer -marm -g -fno-strict-aliasing -std=gnu99 -Wall -Wstrict-prototypes -
> Wdeclaration-after-statement -Wno-unused-but-set-variable -Wno-unused-local-typedefs   -D__XEN_TOOLS_
> _ -MMD -MF .block-qcow.o.d -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -fno-opti
> mize-sibling-calls  -Werror -g -Wno-unused -fno-strict-aliasing -I../include -I../drivers -I/root/xen
> /tools/blktap2/drivers/../../../tools/libxc -I/root/xen/tools/blktap2/drivers/../../../tools/include 
> -D_GNU_SOURCE -DUSE_NFS_LOCKS  -c -o block-qcow.o block-qcow.c 
> block-qcow.c: In function 'get_cluster_offset':
> block-qcow.c:431:3: error: 'tmp_ptr' may be used uninitialized in this function [-Werror=maybe-uninit
> ialized]
>    memcpy(tmp_ptr, l1_ptr, 4096);
>    ^
> block-qcow.c:606:7: error: 'tmp_ptr2' may be used uninitialized in this function [-Werror=maybe-unini
> tialized]
>    if (write(s->fd, tmp_ptr2, 4096) != 4096) {
>        ^
> cc1: all warnings being treated as errors
> /root/xen/tools/blktap2/drivers/../../../tools/Rules.mk:89: recipe for target 'block-qcow.o' failed
> make[5]: *** [block-qcow.o] Error 1
> make[5]: Leaving directory '/root/xen/tools/blktap2/drivers'
> /root/xen/tools/blktap2/../../tools/Rules.mk:105: recipe for target 'subdir-install-drivers' failed
> make[4]: *** [subdir-install-drivers] Error 2
> make[4]: Leaving directory '/root/xen/tools/blktap2'
> /root/xen/tools/blktap2/../../tools/Rules.mk:100: recipe for target 'subdirs-install' failed
> make[3]: *** [subdirs-install] Error 2
> make[3]: Leaving directory '/root/xen/tools/blktap2'
> /root/xen/tools/../tools/Rules.mk:105: recipe for target 'subdir-install-blktap2' failed
> make[2]: *** [subdir-install-blktap2] Error 2
> make[2]: Leaving directory '/root/xen/tools'
> /root/xen/tools/../tools/Rules.mk:100: recipe for target 'subdirs-install' failed
> make[1]: *** [subdirs-install] Error 2
> make[1]: Leaving directory '/root/xen/tools'
> Makefile:96: recipe for target 'install-tools' failed
> make: *** [install-tools] Error 2
> [...]
These emails seems related to this problem:

 http://lists.xen.org/archives/html/xen-devel/2014-06/msg02790.html


Ciao,
L.