linux.git/kernel/trace/trace_functions_graph.c, branch v6.19.12

fgraph: Fix thresh_return nosleeptime double-adjust

2026-03-19T15:15:18+00:00

commit b96d0c59cdbb2a22b2545f6f3d5c6276b05761dd upstream.

trace_graph_thresh_return() called handle_nosleeptime() and then delegated
to trace_graph_return(), which calls handle_nosleeptime() again. When
sleep-time accounting is disabled this double-adjusts calltime and can
produce bogus durations (including underflow).

Fix this by computing rettime once, applying handle_nosleeptime() only
once, using the adjusted calltime for threshold comparison, and writing
the return event directly via __trace_graph_return() when the threshold is
met.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260221113314048jE4VRwIyZEALiYByGK0My@zte.com.cn
Fixes: 3c9880f3ab52b ("ftrace: Use a running sleeptime instead of saving on shadow stack")
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Shengming Hu 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

fgraph: Fix thresh_return clear per-task notrace

2026-03-19T15:15:18+00:00

commit 6ca8379b5d36e22b04e6315c3e49a6083377c862 upstream.

When tracing_thresh is enabled, function graph tracing uses
trace_graph_thresh_return() as the return handler. Unlike
trace_graph_return(), it did not clear the per-task TRACE_GRAPH_NOTRACE
flag set by the entry handler for set_graph_notrace addresses. This could
leave the task permanently in "notrace" state and effectively disable
function graph tracing for that task.

Mirror trace_graph_return()'s per-task notrace handling by clearing
TRACE_GRAPH_NOTRACE and returning early when set.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260221113007819YgrZsMGABff4Rc-O_fZxL@zte.com.cn
Fixes: b84214890a9bc ("function_graph: Move graph notrace bit to shadow stack global var")
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Shengming Hu 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

function_graph: Fix args pointer mismatch in print_graph_retval()

2026-01-23T18:34:38+00:00

When funcgraph-args and funcgraph-retaddr are both enabled, many kernel
functions display invalid parameters in trace logs.

The issue occurs because print_graph_retval() passes a mismatched args
pointer to print_function_args(). Fix this by retrieving the correct
args pointer using the FGRAPH_ENTRY_ARGS() macro.

Link: https://patch.msgid.link/20260112021601.1300479-1-dolinux.peng@gmail.com
Fixes: f83ac7544fbf ("function_graph: Enable funcgraph-args and funcgraph-retaddr to work simultaneously")
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Donglin Peng 
Signed-off-by: Steven Rostedt (Google)

Merge tag 'ftrace-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2025-12-05T18:13:04+00:00

Pull ftrace updates from Steven Rostedt:

 - Fix regression of pid filtering of function graph tracer

   When the function graph tracer allowed multiple instances of graph
   tracing using subops, the filtering by pid broke.

   The ftrace_ops->private that was used for pid filtering wasn't
   updated on creation.

   The wrong function entry callback was used when pid filtering was
   enabled when the function graph tracer started, which meant that
   the pid filtering wasn't happening.

 - Remove no longer needed ftrace_trace_task()

   With PID filtering working via ftrace_pids_enabled() and
   fgraph_pid_func(), the coarse-grained ftrace_trace_task()
   check in graph_entry() is obsolete.

   It was only a fallback for uninitialized op->private (now fixed),
   and its removal ensures consistent PID filtering with standard
   function tracing.

* tag 'ftrace-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  fgraph: Remove coarse PID filtering from graph_entry()
  fgraph: Check ftrace_pids_enabled on registration for early filtering
  fgraph: Initialize ftrace_ops->private for function graph ops

fgraph: Remove coarse PID filtering from graph_entry()

2025-11-26T20:41:35+00:00

With PID filtering working via ftrace_pids_enabled() and fgraph_pid_func,
the coarse-grained ftrace_trace_task() check in graph_entry() is obsolete.

It was only a fallback for uninitialized op->private (now fixed), and its
removal ensures consistent PID filtering with standard function tracing.

Also remove unused ftrace_trace_task() definition from trace.h.

Cc: 
Cc: 
Cc: 
Cc: 
Cc: 
Cc: 
Link: https://patch.msgid.link/20251126173552333XoJZN20143fWbsdTEtWoU@zte.com.cn
Signed-off-by: Shengming Hu 
Signed-off-by: Steven Rostedt (Google)

function_graph: Enable funcgraph-args and funcgraph-retaddr to work simultaneously

2025-11-26T20:13:30+00:00

Currently, the funcgraph-args and funcgraph-retaddr features are
mutually exclusive. This patch resolves this limitation by allowing
funcgraph-retaddr to have an args array.

To verify the change, use perf to trace vfs_write with both options
enabled:

Before:
 # perf ftrace -G vfs_write --graph-opts args,retaddr
   ......
   down_read() { /* <-n_tty_write+0xa3/0x540 */
     __cond_resched(); /* <-down_read+0x12/0x160 */
     preempt_count_add(); /* <-down_read+0x3b/0x160 */
     preempt_count_sub(); /* <-down_read+0x8b/0x160 */
   }

After:
 # perf ftrace -G vfs_write --graph-opts args,retaddr
   ......
   down_read(sem=0xffff8880100bea78) { /* <-n_tty_write+0xa3/0x540 */
     __cond_resched(); /* <-down_read+0x12/0x160 */
     preempt_count_add(val=1); /* <-down_read+0x3b/0x160 */
     preempt_count_sub(val=1); /* <-down_read+0x8b/0x160 */
   }

Cc: Steven Rostedt (Google) 
Cc: Sven Schnelle 
Cc: Masami Hiramatsu 
Cc: Xiaoqin Zhang 
Link: https://patch.msgid.link/20251125093425.2563849-1-dolinux.peng@gmail.com
Signed-off-by: pengdonglin 
Signed-off-by: Steven Rostedt (Google)

fgraph: Make fgraph_no_sleep_time signed

2025-11-26T20:13:28+00:00

The variable fgraph_no_sleep_time changed from being a boolean to being a
counter. A check is made to make sure that it never goes below zero. But
the variable being unsigned makes the check always fail even if it does go
below zero.

Make the variable a signed int so that checking it going below zero still
works.

Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Link: https://patch.msgid.link/20251125104751.4c9c7f28@gandalf.local.home
Fixes: 5abb6ccb58f0 ("tracing: Have function graph tracer option sleep-time be per instance")
Reported-by: Dan Carpenter 
Closes: https://lore.kernel.org/all/aR1yRQxDmlfLZzoo@stanley.mountain/
Signed-off-by: Steven Rostedt (Google)

tracing: Convert function graph set_flags() to use a switch() statement

2025-11-14T19:30:55+00:00

Currently the set_flags() of the function graph tracer has a bunch of:

  if (bit == FLAG1) {
	[..]
  }

  if (bit == FLAG2) {
	[..]
  }

To clean it up a bit, convert it over to a switch statement.

Cc: Masami Hiramatsu 
Cc: Mark Rutland 
Cc: Mathieu Desnoyers 
Cc: Andrew Morton 
Link: https://patch.msgid.link/20251114192319.117123664@kernel.org
Signed-off-by: Steven Rostedt (Google)

tracing: Have function graph tracer option sleep-time be per instance

2025-11-14T19:30:55+00:00

Currently the option to have function graph tracer to ignore time spent
when a task is sleeping is global when the interface is per-instance.
Changing the value in one instance will affect the results of another
instance that is also running the function graph tracer. This can lead to
confusing results.

Cc: Masami Hiramatsu 
Cc: Mark Rutland 
Cc: Mathieu Desnoyers 
Cc: Andrew Morton 
Link: https://patch.msgid.link/20251114192318.950255167@kernel.org
Fixes: c132be2c4fcc1 ("function_graph: Have the instances use their own ftrace_ops for filtering")
Signed-off-by: Steven Rostedt (Google)

tracing: Move graph-time out of function graph options

2025-11-14T19:30:55+00:00

The option "graph-time" affects the function profiler when it is using the
function graph infrastructure. It has nothing to do with the function
graph tracer itself. The option only affects the global function profiler
and does nothing to the function graph tracer.

Move it out of the function graph tracer options and make it a global
option that is only available at the top level instance.

Cc: Masami Hiramatsu 
Cc: Mark Rutland 
Cc: Mathieu Desnoyers 
Cc: Andrew Morton 
Link: https://patch.msgid.link/20251114192318.781711154@kernel.org
Signed-off-by: Steven Rostedt (Google)