Linus,

Fixes for ftrace in v6.13:

- Add needed READ_ONCE() around access to the fgraph array element

  The updates to the fgraph array can happen when callbacks are registered
  and unregistered. The __ftrace_return_to_handler() can handle reading
  either the old value or the new value. But once it reads that value
  it must stay consistent otherwise the check that looks to see if the
  value is a stub may show false, but if the compiler decides to re-read
  after that check, it can be true which can cause the code to crash
  later on.

- Make function profiler use the top level ops for filtering again

  When function graph became available for instances, its filter ops became
  independent from the top level set_ftrace_filter. In the process the
  function profiler received its own filter ops as well. But the function
  profiler uses the top level set_ftrace_filter file and does not have one
  of its own. In giving it its own filter ops, it lost any user interface
  it once had. Make it use the top level set_ftrace_filter file again.
  This fixes a regression.


Please pull the latest ftrace-v6.13-rc5-2 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
ftrace-v6.13-rc5-2

Tag SHA1: 5481b9d16647243f56a1660ee24edb8ea400b6af
Head SHA1: 789a8cff8d2dbe4b5c617c3004b5eb63fa7a3b35


Kohei Enju (1):
      ftrace: Fix function profiler's filtering functionality

Zilin Guan (1):
      fgraph: Add READ_ONCE() when accessing fgraph_array[]

----
 kernel/trace/fgraph.c | 2 +-
 kernel/trace/ftrace.c | 8 ++------
 2 files changed, 3 insertions(+), 7 deletions(-)
---------------------------
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index ddedcb50917f..30e3ddc8a8a8 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -833,7 +833,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
 #endif
 	{
 		for_each_set_bit(i, &bitmap, sizeof(bitmap) * BITS_PER_BYTE) {
-			struct fgraph_ops *gops = fgraph_array[i];
+			struct fgraph_ops *gops = READ_ONCE(fgraph_array[i]);
 
 			if (gops == &fgraph_stub)
 				continue;
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);
 }

The pull request you sent on Thu, 2 Jan 2025 17:32:54 -0500:

> git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git ftrace-v6.13-rc5-2

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/e30dd219c75023afc5f5ba76dbeb48e926cea645

Thank you!

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