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SubjectRe: [tip:perf/core] perf events: Fix false positive build warning with older GCC's
tip-bot for Ingo Molnar wrote:
> Commit-ID: 55632770d7298835645489828af87f854c47749c
> Gitweb: http://git.kernel.org/tip/55632770d7298835645489828af87f854c47749c
> Author: Ingo Molnar <mingo@elte.hu>
> AuthorDate: Thu, 18 Mar 2010 16:51:16 +0100
> Committer: Ingo Molnar <mingo@elte.hu>
> CommitDate: Thu, 18 Mar 2010 17:03:24 +0100
>
> perf events: Fix false positive build warning with older GCC's
>
> gcc 4.2.1 produces:
>
> util/probe-event.c: In function 'add_perf_probe_events':
> util/probe-event.c:883: warning: 'tev' may be used uninitialized in this function
> make: *** [util/probe-event.o] Error 1
>
> Newer GCCs get this right.
>
> To work it around, initialize the variable to NULL so that older GCCs see
> it as initialized too.

Hmm, indeed. this code implies that ntevs > 0, it seems that we'd better
check it first (e.g. 'if(ntevs <= 0) return;') too.
Thank you,

>
> Cc: Masami Hiramatsu <mhiramat@redhat.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> LKML-Reference: <20100316220612.32050.33806.stgit@localhost6.localdomain6>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> ---
> tools/perf/util/probe-event.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index f333269..c6603f3 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -880,7 +880,7 @@ static void __add_kprobe_trace_events(struct perf_probe_event *pev,
> int ntevs, bool allow_suffix)
> {
> int i, fd;
> - struct kprobe_trace_event *tev;
> + struct kprobe_trace_event *tev = NULL;
> char buf[64];
> const char *event, *group;
> struct strlist *namelist;
> --
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--
Masami Hiramatsu
e-mail: mhiramat@redhat.com


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