Messages in this thread Patch in this message | | | From | Julien Thierry <> | Subject | [PATCH v2 3/3] perf: Fix ftrace builtin when kernel doesn't have function_graph | Date | Fri, 3 Nov 2017 11:44:18 +0000 |
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When linux is built without support for function graph tracer, the ftrace builtin of perf will fail when trying to reset max_graph_depth because the file does not exist. This prevents the use of function tracer from perf.
Only try to write the file max_graph_depth file when it exists.
Signed-off-by: Julien Thierry <julien.thierry@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: linux-kernel@vger.kernel.org --- tools/perf/builtin-ftrace.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c index 25a42ac..1abc066 100644 --- a/tools/perf/builtin-ftrace.c +++ b/tools/perf/builtin-ftrace.c @@ -14,6 +14,7 @@ #include <signal.h> #include <fcntl.h> #include <poll.h> +#include <sys/stat.h>
#include "debug.h" #include <subcmd/parse-options.h> @@ -116,6 +117,13 @@ static int append_tracing_file(const char *name, const char *val) static int reset_tracing_cpu(void); static void reset_tracing_filters(void);
+static inline bool tracing_file_accessible(const char *name) +{ + struct stat s; + + return stat(get_tracing_file(name), &s) == 0; +} + static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused) { if (write_tracing_file("tracing_on", "0") < 0) @@ -130,8 +138,12 @@ static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused) if (reset_tracing_cpu() < 0) return -1;
- if (write_tracing_file("max_graph_depth", "0") < 0) + if (!tracing_file_accessible("max_graph_depth")) { + if (!strcmp(ftrace->tracer, "function_graph")) + return -1; + } else if (write_tracing_file("max_graph_depth", "0") < 0) { return -1; + }
reset_tracing_filters(); return 0; -- 1.9.1
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