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SubjectRe: [PATCH] TRACING: Fix a copmile warning

On Mon, Jul 25, 2011 at 4:19 PM, Steven Rostedt <> wrote:
> On Mon, 2011-07-25 at 15:43 -0400, Arnaud Lacombe wrote:
>> Actually, we have a special uninitialized_var(x) macro to handle such
>> false positive. From include/linux/compiler-gcc.h:
>> /*
>>  * A trick to suppress uninitialized variable warning without generating any
>>  * code
>>  */
>> #define uninitialized_var(x) x = x
> I'm aware of that too, but I think that is inappropriate as well. As I
> said, some versions of gcc report it, others don't. Seems that gcc 4.6.0
> says this is an error where 4.5.1 does not (I just tried both).
did you ? gcc 4.5.1 from Fedora 14 definitively shows the warning:

# make ARCH=i386 kernel/trace/trace_printk.o V=1
gcc -Wp,-MD,kernel/trace/.trace_printk.o.d -nostdinc -isystem
/usr/lib/gcc/x86_64-redhat-linux/4.5.1/include [...] -c -o
kernel/trace/trace_printk.o kernel/trace/trace_printk.c
/src/linux/linux/kernel/trace/trace_printk.c: In function
/src/linux/linux/kernel/trace/trace_printk.c:52:8: warning: 'fmt' may
be used uninitialized in this function

# gcc -v
gcc -v
Using built-in specs.
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--with-bugurl= --enable-bootstrap
--enable-shared --enable-threads=posix --enable-checking=release
--with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-gnu-unique-object
--enable-plugin --enable-java-awt=gtk --disable-dssi
--enable-libgcj-multifile --enable-java-maintainer-mode
--disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic
--with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.5.1 20100924 (Red Hat 4.5.1-4) (GCC)

- Arnaud
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