When trying to build the new libpfm-4.13.0 as an rpm for various architectures
I found that the builds failed on some machines because the compiler found that
p could be uninitialized in gen_tracepoint_table. Attached is a patch that
fixes that specific issue.
-Will
commit 874feacbbe97fe567d3d8b1582d881d1b424dd5e
Author: William Cohen <wco...@redhat.com>
Date: Fri Apr 14 16:07:07 2023 -0400
Make sure that p is set to a known value before using.
Need to ensure that p was initialized at the start of function
gen_tracepoint_table otherwise on some architectures such as s390x
will get the following error when compiling with -Werror:
make[1]: Entering directory '/root/rpmbuild/BUILD/libpfm-4.13.0/lib'
cc -O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -march=z14 -mtune=z15 -fasynchronous-unwind-tables -fstack-clash-protection -g -Wall -Werror -Wextra -Wno-unused-parameter -I. -I/root/rpmbuild/BUILD/libpfm-4.13.0/lib/../include -DCONFIG_PFMLIB_DEBUG -DCONFIG_PFMLIB_OS_LINUX -D_REENTRANT -I. -fvisibility=hidden -DCONFIG_PFMLIB_ARCH_S390X -I. -c pfmlib_perf_event_pmu.c
pfmlib_perf_event_pmu.c: In function 'gen_tracepoint_table':
pfmlib_perf_event_pmu.c:434:35: error: 'p' may be used uninitialized in this function [-Werror=maybe-uninitialized]
434 | p->modmsk = 0;
| ~~~~~~~~~~^~~
cc1: all warnings being treated as errors
diff --git a/lib/pfmlib_perf_event_pmu.c b/lib/pfmlib_perf_event_pmu.c
index 637c5b1..8f7d7d1 100644
--- a/lib/pfmlib_perf_event_pmu.c
+++ b/lib/pfmlib_perf_event_pmu.c
@@ -361,7 +361,7 @@ gen_tracepoint_table(void)
{
DIR *dir1, *dir2;
struct dirent *d1, *d2;
- perf_event_t *p;
+ perf_event_t *p = NULL;
perf_umask_t *um;
char d2path[MAXPATHLEN];
char idpath[MAXPATHLEN];
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