From 5411aefc01894b274ed7c3c20fbbf36e38540363 Mon Sep 17 00:00:00 2001 From: He Zhe Date: Fri, 2 Aug 2019 16:29:51 +0800 Subject: [PATCH] perf ftrace: Fix failure to set cpumask when only one cpu is present [ Upstream commit cf30ae726c011e0372fd4c2d588466c8b50a8907 ] The buffer containing the string used to set cpumask is overwritten at the end of the string later in cpu_map__snprint_mask due to not enough memory space, when there is only one cpu. And thus causes the following failure: $ perf ftrace ls failed to reset ftrace $ This patch fixes the calculation of the cpumask string size. Signed-off-by: He Zhe Tested-by: Arnaldo Carvalho de Melo Cc: Alexander Shishkin Cc: Alexey Budankov Cc: Jiri Olsa Cc: Kan Liang Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Stephane Eranian Fixes: dc23103278c5 ("perf ftrace: Add support for -a and -C option") Link: http://lkml.kernel.org/r/1564734592-15624-1-git-send-email-zhe.he@windriver.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin --- tools/perf/builtin-ftrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c index 25a42acabee1..13a33fb71a6d 100644 --- a/tools/perf/builtin-ftrace.c +++ b/tools/perf/builtin-ftrace.c @@ -162,7 +162,7 @@ static int set_tracing_cpumask(struct cpu_map *cpumap) int last_cpu; last_cpu = cpu_map__cpu(cpumap, cpumap->nr - 1); - mask_size = (last_cpu + 3) / 4 + 1; + mask_size = last_cpu / 4 + 2; /* one more byte for EOS */ mask_size += last_cpu / 32; /* ',' is needed for every 32th cpus */ cpumask = malloc(mask_size); -- 2.20.1