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tracing: Always use canonical ftrace path

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The canonical location for the tracefs filesystem is at /sys/kernel/tracing.

But, from Documentation/trace/ftrace.rst:

  Before 4.1, all ftrace tracing control files were within the debugfs
  file system, which is typically located at /sys/kernel/debug/tracing.
  For backward compatibility, when mounting the debugfs file system,
  the tracefs file system will be automatically mounted at:

  /sys/kernel/debug/tracing

Many comments and Kconfig help messages in the tracing code still refer
to this older debugfs path, so let's update them to avoid confusion.

Link: https://lore.kernel.org/linux-trace-kernel/20230215223350.2658616-2-zwisler@google.com

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Signed-off-by: Ross Zwisler <zwisler@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Ross Zwisler 2023-02-15 15:33:45 -07:00 committed by Steven Rostedt (Google)
parent d8f0ae3ebe
commit 2455f0e124
11 changed files with 25 additions and 25 deletions
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2
include/linux/kernel.h
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@ -297,7 +297,7 @@ bool mac_pton(const char *s, u8 *mac);
*
* Use tracing_on/tracing_off when you want to quickly turn on or off
* tracing. It simply enables or disables the recording of the trace events.
* This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
* This also corresponds to the user space /sys/kernel/tracing/tracing_on
* file, which gives a means for the kernel and userspace to interact.
* Place a tracing_off() in the kernel where you want tracing to end.
* From user space, examine the trace, and then echo 1 > tracing_on

4
include/linux/tracepoint.h
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@ -471,7 +471,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
* * This is how the trace record is structured and will
* * be saved into the ring buffer. These are the fields
* * that will be exposed to user-space in
* * /sys/kernel/debug/tracing/events/<*>/format.
* * /sys/kernel/tracing/events/<*>/format.
* *
* * The declared 'local variable' is called '__entry'
* *
@ -531,7 +531,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
* tracepoint callback (this is used by programmatic plugins and
* can also by used by generic instrumentation like SystemTap), and
* it is also used to expose a structured trace record in
* /sys/kernel/debug/tracing/events/.
* /sys/kernel/tracing/events/.
*
* A set of (un)registration functions can be passed to the variant
* TRACE_EVENT_FN to perform any (un)registration work.

20
kernel/trace/Kconfig
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@ -239,7 +239,7 @@ config DYNAMIC_FTRACE
enabled, and the functions not enabled will not affect
performance of the system.
See the files in /sys/kernel/debug/tracing:
See the files in /sys/kernel/tracing:
available_filter_functions
set_ftrace_filter
set_ftrace_notrace
@ -299,7 +299,7 @@ config STACK_TRACER
select KALLSYMS
help
This special tracer records the maximum stack footprint of the
kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
kernel and displays it in /sys/kernel/tracing/stack_trace.
This tracer works by hooking into every function call that the
kernel executes, and keeping a maximum stack depth value and
@ -339,7 +339,7 @@ config IRQSOFF_TRACER
disabled by default and can be runtime (re-)started
via:
echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
echo 0 > /sys/kernel/tracing/tracing_max_latency
(Note that kernel size and overhead increase with this option
enabled. This option and the preempt-off timing option can be
@ -363,7 +363,7 @@ config PREEMPT_TRACER
disabled by default and can be runtime (re-)started
via:
echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
echo 0 > /sys/kernel/tracing/tracing_max_latency
(Note that kernel size and overhead increase with this option
enabled. This option and the irqs-off timing option can be
@ -515,7 +515,7 @@ config TRACER_SNAPSHOT
Allow tracing users to take snapshot of the current buffer using the
ftrace interface, e.g.:
echo 1 > /sys/kernel/debug/tracing/snapshot
echo 1 > /sys/kernel/tracing/snapshot
cat snapshot
config TRACER_SNAPSHOT_PER_CPU_SWAP
@ -527,7 +527,7 @@ config TRACER_SNAPSHOT_PER_CPU_SWAP
full swap (all buffers). If this is set, then the following is
allowed:
echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
echo 1 > /sys/kernel/tracing/per_cpu/cpu2/snapshot
After which, only the tracing buffer for CPU 2 was swapped with
the main tracing buffer, and the other CPU buffers remain the same.
@ -574,7 +574,7 @@ config PROFILE_ANNOTATED_BRANCHES
This tracer profiles all likely and unlikely macros
in the kernel. It will display the results in:
/sys/kernel/debug/tracing/trace_stat/branch_annotated
/sys/kernel/tracing/trace_stat/branch_annotated
Note: this will add a significant overhead; only turn this
on if you need to profile the system's use of these macros.
@ -587,7 +587,7 @@ config PROFILE_ALL_BRANCHES
taken in the kernel is recorded whether it hit or miss.
The results will be displayed in:
/sys/kernel/debug/tracing/trace_stat/branch_all
/sys/kernel/tracing/trace_stat/branch_all
This option also enables the likely/unlikely profiler.
@ -638,8 +638,8 @@ config BLK_DEV_IO_TRACE
Tracing also is possible using the ftrace interface, e.g.:
echo 1 > /sys/block/sda/sda1/trace/enable
echo blk > /sys/kernel/debug/tracing/current_tracer
cat /sys/kernel/debug/tracing/trace_pipe
echo blk > /sys/kernel/tracing/current_tracer
cat /sys/kernel/tracing/trace_pipe
If unsure, say N.

2
kernel/trace/kprobe_event_gen_test.c
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@ -21,7 +21,7 @@
* Then:
*
* # insmod kernel/trace/kprobe_event_gen_test.ko
* # cat /sys/kernel/debug/tracing/trace
* # cat /sys/kernel/tracing/trace
*
* You should see many instances of the "gen_kprobe_test" and
* "gen_kretprobe_test" events in the trace buffer.

2
kernel/trace/ring_buffer.c
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@ -2886,7 +2886,7 @@ rb_check_timestamp(struct ring_buffer_per_cpu *cpu_buffer,
sched_clock_stable() ? "" :
"If you just came from a suspend/resume,\n"
"please switch to the trace global clock:\n"
" echo global > /sys/kernel/debug/tracing/trace_clock\n"
" echo global > /sys/kernel/tracing/trace_clock\n"
"or add trace_clock=global to the kernel command line\n");
}

2
kernel/trace/synth_event_gen_test.c
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@ -22,7 +22,7 @@
* Then:
*
* # insmod kernel/trace/synth_event_gen_test.ko
* # cat /sys/kernel/debug/tracing/trace
* # cat /sys/kernel/tracing/trace
*
* You should see several events in the trace buffer -
* "create_synth_test", "empty_synth_test", and several instances of

2
kernel/trace/trace.c
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@ -1187,7 +1187,7 @@ void tracing_snapshot_instance(struct trace_array *tr)
*
* Note, make sure to allocate the snapshot with either
* a tracing_snapshot_alloc(), or by doing it manually
* with: echo 1 > /sys/kernel/debug/tracing/snapshot
* with: echo 1 > /sys/kernel/tracing/snapshot
*
* If the snapshot buffer is not allocated, it will stop tracing.
* Basically making a permanent snapshot.

4
samples/user_events/example.c
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@ -23,8 +23,8 @@
#endif
/* Assumes debugfs is mounted */
const char *data_file = "/sys/kernel/debug/tracing/user_events_data";
const char *status_file = "/sys/kernel/debug/tracing/user_events_status";
const char *data_file = "/sys/kernel/tracing/user_events_data";
const char *status_file = "/sys/kernel/tracing/user_events_status";
static int event_status(long **status)
{

6
scripts/tracing/draw_functrace.py
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@ -12,9 +12,9 @@ calls. Only the functions's names and the call time are provided.
Usage:
Be sure that you have CONFIG_FUNCTION_TRACER
# mount -t debugfs nodev /sys/kernel/debug
# echo function > /sys/kernel/debug/tracing/current_tracer
$ cat /sys/kernel/debug/tracing/trace_pipe > ~/raw_trace_func
# mount -t tracefs nodev /sys/kernel/tracing
# echo function > /sys/kernel/tracing/current_tracer
$ cat /sys/kernel/tracing/trace_pipe > ~/raw_trace_func
Wait some times but not too much, the script is a bit slow.
Break the pipe (Ctrl + Z)
$ scripts/tracing/draw_functrace.py < ~/raw_trace_func > draw_functrace

4
tools/lib/api/fs/tracing_path.c
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@ -14,8 +14,8 @@
#include "tracing_path.h"
static char tracing_mnt[PATH_MAX] = "/sys/kernel/debug";
static char tracing_path[PATH_MAX] = "/sys/kernel/debug/tracing";
static char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events";
static char tracing_path[PATH_MAX] = "/sys/kernel/tracing";
static char tracing_events_path[PATH_MAX] = "/sys/kernel/tracing/events";
static void __tracing_path_set(const char *tracing, const char *mountpoint)
{

2
tools/tracing/latency/latency-collector.c
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@ -1584,7 +1584,7 @@ static void *do_printloop(void *arg)
/*
* Toss a coin to decide if we want to sleep before printing
* out the backtrace. The reason for this is that opening
* /sys/kernel/debug/tracing/trace will cause a blackout of
* /sys/kernel/tracing/trace will cause a blackout of
* hundreds of ms, where no latencies will be noted by the
* latency tracer. Thus by randomly sleeping we try to avoid
* missing traces systematically due to this. With this option