[for-linus][PATCH 0/3] More tracing fixes for 5.12

[for-linus][PATCH 0/3] More tracing fixes for 5.12

[Steven Rostedt]

Functional fix:

 - Memory leak in __create_synth_event()

 - Skip selftests if tracing is disabled

Non functional fix:

 - Fix stale comment about the trace_event_call flags.

Steven Rostedt (VMware) (2):
      tracing: Skip selftests if tracing is disabled
      tracing: Fix comment about the trace_event_call flags

Vamshi K Sthambamkadi (1):
      tracing: Fix memory leak in __create_synth_event()

----
 include/linux/trace_events.h      | 11 ++---------
 kernel/trace/trace.c              |  6 ++++++
 kernel/trace/trace_events_synth.c |  4 +++-
 3 files changed, 11 insertions(+), 10 deletions(-)

[for-linus][PATCH 1/3] tracing: Fix memory leak in __create_synth_event()

[Steven Rostedt]

From: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>

kmemleak report:
unreferenced object 0xc5a6f708 (size 8):
  comm "ftracetest", pid 1209, jiffies 4294911500 (age 6.816s)
  hex dump (first 8 bytes):
    00 c1 3d 60 14 83 1f 8a                          ..=`....
  backtrace:
    [<f0aa4ac4>] __kmalloc_track_caller+0x2a6/0x460
    [<7d3d60a6>] kstrndup+0x37/0x70
    [<45a0e739>] argv_split+0x1c/0x120
    [<c17982f8>] __create_synth_event+0x192/0xb00
    [<0708b8a3>] create_synth_event+0xbb/0x150
    [<3d1941e1>] create_dyn_event+0x5c/0xb0
    [<5cf8b9e3>] trace_parse_run_command+0xa7/0x140
    [<04deb2ef>] dyn_event_write+0x10/0x20
    [<8779ac95>] vfs_write+0xa9/0x3c0
    [<ed93722a>] ksys_write+0x89/0xc0
    [<b9ca0507>] __ia32_sys_write+0x15/0x20
    [<7ce02d85>] __do_fast_syscall_32+0x45/0x80
    [<cb0ecb35>] do_fast_syscall_32+0x29/0x60
    [<2467454a>] do_SYSENTER_32+0x15/0x20
    [<9beaa61d>] entry_SYSENTER_32+0xa9/0xfc
unreferenced object 0xc5a6f078 (size 8):
  comm "ftracetest", pid 1209, jiffies 4294911500 (age 6.816s)
  hex dump (first 8 bytes):
    08 f7 a6 c5 00 00 00 00                          ........
  backtrace:
    [<bbac096a>] __kmalloc+0x2b6/0x470
    [<aa2624b4>] argv_split+0x82/0x120
    [<c17982f8>] __create_synth_event+0x192/0xb00
    [<0708b8a3>] create_synth_event+0xbb/0x150
    [<3d1941e1>] create_dyn_event+0x5c/0xb0
    [<5cf8b9e3>] trace_parse_run_command+0xa7/0x140
    [<04deb2ef>] dyn_event_write+0x10/0x20
    [<8779ac95>] vfs_write+0xa9/0x3c0
    [<ed93722a>] ksys_write+0x89/0xc0
    [<b9ca0507>] __ia32_sys_write+0x15/0x20
    [<7ce02d85>] __do_fast_syscall_32+0x45/0x80
    [<cb0ecb35>] do_fast_syscall_32+0x29/0x60
    [<2467454a>] do_SYSENTER_32+0x15/0x20
    [<9beaa61d>] entry_SYSENTER_32+0xa9/0xfc

In __create_synth_event(), while iterating field/type arguments, the
argv_split() will return array of atleast 2 elements even when zero
arguments(argc=0) are passed. for e.g. when there is double delimiter
or string ends with delimiter

To fix call argv_free() even when argc=0.

Link: https://lkml.kernel.org/r/20210304094521.GA1826@cosmos

Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_events_synth.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index 2979a96595b4..8d71e6c83f10 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -1225,8 +1225,10 @@ static int __create_synth_event(const char *name, const char *raw_fields)
 			goto err;
 		}
 
-		if (!argc)
+		if (!argc) {
+			argv_free(argv);
 			continue;
+		}
 
 		n_fields_this_loop = 0;
 		consumed = 0;
-- 
2.30.0

[for-linus][PATCH 2/3] tracing: Skip selftests if tracing is disabled

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

If tracing is disabled for some reason (traceoff_on_warning, command line,
etc), the ftrace selftests are guaranteed to fail, as their results are
defined by trace data in the ring buffers. If the ring buffers are turned
off, the tests will fail, due to lack of data.

Because tracing being disabled is for a specific reason (warning, user
decided to, etc), it does not make sense to enable tracing to run the self
tests, as the test output may corrupt the reason for the tracing to be
disabled.

Instead, simply skip the self tests and report that they are being skipped
due to tracing being disabled.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index e295c413580e..eccb4e1187cc 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1929,6 +1929,12 @@ static int run_tracer_selftest(struct tracer *type)
 	if (!selftests_can_run)
 		return save_selftest(type);
 
+	if (!tracing_is_on()) {
+		pr_warn("Selftest for tracer %s skipped due to tracing disabled\n",
+			type->name);
+		return 0;
+	}
+
 	/*
 	 * Run a selftest on this tracer.
 	 * Here we reset the trace buffer, and set the current
-- 
2.30.0

[for-linus][PATCH 3/3] tracing: Fix comment about the trace_event_call flags

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

In the declaration of the struct trace_event_call, the flags has the bits
defined in the comment above it. But these bits are also defined by the
TRACE_EVENT_FL_* enums just above the declaration of the struct. As the
comment about the flags in the struct has become stale and incorrect, just
replace it with a reference to the TRACE_EVENT_FL_* enum above.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 include/linux/trace_events.h | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 7077fec653bb..28e7af1406f2 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -349,15 +349,8 @@ struct trace_event_call {
 	struct event_filter	*filter;
 	void			*mod;
 	void			*data;
-	/*
-	 *   bit 0:		filter_active
-	 *   bit 1:		allow trace by non root (cap any)
-	 *   bit 2:		failed to apply filter
-	 *   bit 3:		trace internal event (do not enable)
-	 *   bit 4:		Event was enabled by module
-	 *   bit 5:		use call filter rather than file filter
-	 *   bit 6:		Event is a tracepoint
-	 */
+
+	/* See the TRACE_EVENT_FL_* flags above */
 	int			flags; /* static flags of different events */
 
 #ifdef CONFIG_PERF_EVENTS
-- 
2.30.0