ftrace: Fix function profiler's filtering functionality

JIRA: https://issues.redhat.com/browse/RHEL-86682

commit 789a8cf
Author: Kohei Enju <enjuk@amazon.com>
Date:   Thu Jan 2 04:08:20 2025 +0900

    ftrace: Fix function profiler's filtering functionality

    Commit c132be2 ("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@localhost:~# echo 'vfs*' > /sys/kernel/tracing/set_ftrace_filter
    root@localhost:~# echo 1 > /sys/kernel/tracing/function_profile_enabled
    root@localhost:~# sleep 1
    root@localhost:~# echo 0 > /sys/kernel/tracing/function_profile_enabled
    root@localhost:~# 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@localhost:~# echo 'vfs*' > /sys/kernel/tracing/set_ftrace_filter
    root@localhost:~# echo 1 > /sys/kernel/tracing/function_profile_enabled
    root@localhost:~# sleep 1
    root@localhost:~# echo 0 > /sys/kernel/tracing/function_profile_enabled
    root@localhost:~# 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@vger.kernel.org
    Link: https://lore.kernel.org/20250101190820.72534-1-enjuk@amazon.com
    Fixes: c132be2 ("function_graph: Have the instances use their own ftrace_ops for filtering")
    Signed-off-by: Kohei Enju <enjuk@amazon.com>
    Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>

Author: jeromemarchand

kernel/trace/ftrace.c

@@ -883,16 +883,13 @@ 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);
 }
 
@@ -903,12 +900,11 @@ 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);
 }