linux-kernel - [for-linus][PATCH 2/2] ftrace: Fix function profilers filtering functionality

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Message-ID: <20250102220310.109629698@goodmis.org>
Date: Thu, 02 Jan 2025 17:02:40 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 stable@...r.kernel.org,
 Kohei Enju <enjuk@...zon.com>
Subject: [for-linus][PATCH 2/2] ftrace: Fix function profilers filtering functionality

From: Kohei Enju <enjuk@...zon.com>

Commit c132be2c4fcc ("function_graph: Have the instances use their own
ftrace_ops for filtering"), function profiler (enabled via
function_profile_enabled) has been showing statistics for all functions,
ignoring set_ftrace_filter settings.

While tracers are instantiated, the function profiler is not. Therefore, it
should use the global set_ftrace_filter for consistency.  This patch
modifies the function profiler to use the global filter, fixing the
filtering functionality.

Before (filtering not working):
```
root@...alhost:~# echo 'vfs*' > /sys/kernel/tracing/set_ftrace_filter
root@...alhost:~# echo 1 > /sys/kernel/tracing/function_profile_enabled
root@...alhost:~# sleep 1
root@...alhost:~# echo 0 > /sys/kernel/tracing/function_profile_enabled
root@...alhost:~# head /sys/kernel/tracing/trace_stat/*
  Function                               Hit    Time            Avg
     s^2
  --------                               ---    ----            ---
     ---
  schedule                               314    22290594 us     70989.15 us
     40372231 us
  x64_sys_call                          1527    8762510 us      5738.382 us
     3414354 us
  schedule_hrtimeout_range               176    8665356 us      49234.98 us
     405618876 us
  __x64_sys_ppoll                        324    5656635 us      17458.75 us
     19203976 us
  do_sys_poll                            324    5653747 us      17449.83 us
     19214945 us
  schedule_timeout                        67    5531396 us      82558.15 us
     2136740827 us
  __x64_sys_pselect6                      12    3029540 us      252461.7 us
     63296940171 us
  do_pselect.constprop.0                  12    3029532 us      252461.0 us
     63296952931 us
```

After (filtering working):
```
root@...alhost:~# echo 'vfs*' > /sys/kernel/tracing/set_ftrace_filter
root@...alhost:~# echo 1 > /sys/kernel/tracing/function_profile_enabled
root@...alhost:~# sleep 1
root@...alhost:~# echo 0 > /sys/kernel/tracing/function_profile_enabled
root@...alhost:~# head /sys/kernel/tracing/trace_stat/*
  Function                               Hit    Time            Avg
     s^2
  --------                               ---    ----            ---
     ---
  vfs_write                              462    68476.43 us     148.217 us
     25874.48 us
  vfs_read                               641    9611.356 us     14.994 us
     28868.07 us
  vfs_fstat                              890    878.094 us      0.986 us
     1.667 us
  vfs_fstatat                            227    757.176 us      3.335 us
     18.928 us
  vfs_statx                              226    610.610 us      2.701 us
     17.749 us
  vfs_getattr_nosec                     1187    460.919 us      0.388 us
     0.326 us
  vfs_statx_path                         297    343.287 us      1.155 us
     11.116 us
  vfs_rename                               6    291.575 us      48.595 us
     9889.236 us
```

Cc: stable@...r.kernel.org
Link: https://lore.kernel.org/20250101190820.72534-1-enjuk@amazon.com
Fixes: c132be2c4fcc ("function_graph: Have the instances use their own ftrace_ops for filtering")
Signed-off-by: Kohei Enju <enjuk@...zon.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 kernel/trace/ftrace.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 9b17efb1a87d..2e113f8b13a2 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -902,16 +902,13 @@ static void profile_graph_return(struct ftrace_graph_ret *trace,
 }
 
 static struct fgraph_ops fprofiler_ops = {
-	.ops = {
-		.flags = FTRACE_OPS_FL_INITIALIZED,
-		INIT_OPS_HASH(fprofiler_ops.ops)
-	},
 	.entryfunc = &profile_graph_entry,
 	.retfunc = &profile_graph_return,
 };
 
 static int register_ftrace_profiler(void)
 {
+	ftrace_ops_set_global_filter(&fprofiler_ops.ops);
 	return register_ftrace_graph(&fprofiler_ops);
 }
 
@@ -922,12 +919,11 @@ static void unregister_ftrace_profiler(void)
 #else
 static struct ftrace_ops ftrace_profile_ops __read_mostly = {
 	.func		= function_profile_call,
-	.flags		= FTRACE_OPS_FL_INITIALIZED,
-	INIT_OPS_HASH(ftrace_profile_ops)
 };
 
 static int register_ftrace_profiler(void)
 {
+	ftrace_ops_set_global_filter(&ftrace_profile_ops);
 	return register_ftrace_function(&ftrace_profile_ops);
 }
 
-- 
2.45.2