From c3d59cfde9cc1fa699eb6bf0d3ce4156354e3a98 Mon Sep 17 00:00:00 2001 From: Thomas Richter Date: Tue, 9 Mar 2021 12:04:47 +0100 Subject: [PATCH] perf synthetic-events: Fix uninitialized 'kernel_thread' variable MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit perf build fails on 5.12.0rc2 on s390 with this error message: util/synthetic-events.c: In function ‘__event__synthesize_thread.part.0.isra’: util/synthetic-events.c:787:19: error: ‘kernel_thread’ may be used uninitialized in this function [-Werror=maybe-uninitialized] 787 | if (_pid == pid && !kernel_thread) { | ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~ The build succeeds using command 'make DEBUG=y'. The variable kernel_thread is set by this function sequence: __event__synthesize_thread() | defines bool kernel_thread; as local variable and calls +--> perf_event__prepare_comm(..., &kernel_thread) +--> perf_event__get_comm_ids(..., bool *kernel); On return of this function variable kernel is always set to true or false. To prevent this compile error, assign variable kernel_thread a value when it is defined. Output after: [root@m35lp76 perf]# make util/synthetic-events.o .... CC util/synthetic-events.o [root@m35lp76 perf]# Fixes: c1b907953b2cd9ff ("perf tools: Skip PERF_RECORD_MMAP event synthesis for kernel threads") Signed-off-by: Thomas Richter Cc: Heiko Carstens Cc: Namhyung Kim Cc: Sumanth Korikkar Cc: Sven Schnelle Cc: Vasily Gorbik Link: http://lore.kernel.org/lkml/20210309110447.834292-1-tmricht@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/synthetic-events.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c index b698046..5dd4516 100644 --- a/tools/perf/util/synthetic-events.c +++ b/tools/perf/util/synthetic-events.c @@ -758,7 +758,7 @@ static int __event__synthesize_thread(union perf_event *comm_event, for (i = 0; i < n; i++) { char *end; pid_t _pid; - bool kernel_thread; + bool kernel_thread = false; _pid = strtol(dirent[i]->d_name, &end, 10); if (*end) -- 2.7.4