From ef2c3e76d98dfb69a46d870b47656e8e5bac6e2b Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Thu, 13 Oct 2016 17:12:35 -0300 Subject: [PATCH] perf jit: Avoid returning garbage for a ret variable When the loop body isn't executed at all, then the 'ret' local variable, that is uninitialized will be used as the return value. This triggers this error on Alpine Linux: CC /tmp/build/perf/util/demangle-java.o CC /tmp/build/perf/util/demangle-rust.o CC /tmp/build/perf/util/jitdump.o CC /tmp/build/perf/util/genelf.o util/jitdump.c: In function 'jit_process': util/jitdump.c:622:3: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized] fprintf(stderr, "injected: %s (%d)\n", path, ret); ^ util/jitdump.c:584:6: note: 'ret' was declared here int ret; ^ FLEX /tmp/build/perf/util/parse-events-flex.c / $ gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-alpine-linux-musl/5.3.0/lto-wrapper Target: x86_64-alpine-linux-musl Configured with: /home/buildozer/aports/main/gcc/src/gcc-5.3.0/configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info +--build=x86_64-alpine-linux-musl --host=x86_64-alpine-linux-musl --target=x86_64-alpine-linux-musl --with-pkgversion='Alpine 5.3.0' --enable-checking=release +--disable-fixed-point --disable-libstdcxx-pch --disable-multilib --disable-nls --disable-werror --disable-symvers --enable-__cxa_atexit --enable-esp +--enable-cloog-backend --enable-languages=c,c++,objc,java,fortran,ada --disable-libssp --disable-libmudflap --disable-libsanitizer --enable-shared +--enable-threads --enable-tls --with-system-zlib Thread model: posix gcc version 5.3.0 (Alpine 5.3.0) But this so far got under the radar, not causing any build problem, till the "perf jit: enable jitdump support without dwarf" gets applied, when the above problem takes place, some combination of inlining or whatever, the problem is real, so fix it by initializing the variable to zero. Cc: Anton Blanchard Cc: Jiri Olsa Cc: Maciej Debski Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Stephane Eranian Link: https://lkml.kernel.org/r/20161013200437.GA12815@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/jitdump.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/util/jitdump.c b/tools/perf/util/jitdump.c index 95f0884..f3ed3c9 100644 --- a/tools/perf/util/jitdump.c +++ b/tools/perf/util/jitdump.c @@ -581,7 +581,7 @@ static int jit_process_dump(struct jit_buf_desc *jd) { union jr_entry *jr; - int ret; + int ret = 0; while ((jr = jit_get_next_entry(jd))) { switch(jr->prefix.id) { -- 2.7.4