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tracing: Always use canonical ftrace path 

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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

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 * 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. * 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. * 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. * 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 * 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 * * This is how the trace record is structured and will
* * be saved into the ring buffer. These are the fields * * be saved into the ring buffer. These are the fields
* * that will be exposed to user-space in * * 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' * * 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 * tracepoint callback (this is used by programmatic plugins and
* can also by used by generic instrumentation like SystemTap), and * can also by used by generic instrumentation like SystemTap), and
* it is also used to expose a structured trace record in * 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 * A set of (un)registration functions can be passed to the variant
* TRACE_EVENT_FN to perform any (un)registration work. * 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 enabled, and the functions not enabled will not affect
performance of the system. performance of the system.
See the files in /sys/kernel/debug/tracing: See the files in /sys/kernel/tracing:
available_filter_functions available_filter_functions
set_ftrace_filter set_ftrace_filter
set_ftrace_notrace set_ftrace_notrace
@ -299,7 +299,7 @@ config STACK_TRACER
select KALLSYMS select KALLSYMS
help help
This special tracer records the maximum stack footprint of the 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 This tracer works by hooking into every function call that the
kernel executes, and keeping a maximum stack depth value and 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 disabled by default and can be runtime (re-)started
via: 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 (Note that kernel size and overhead increase with this option
enabled. This option and the preempt-off timing option can be 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 disabled by default and can be runtime (re-)started
via: 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 (Note that kernel size and overhead increase with this option
enabled. This option and the irqs-off timing option can be 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 Allow tracing users to take snapshot of the current buffer using the
ftrace interface, e.g.: ftrace interface, e.g.:
echo 1 > /sys/kernel/debug/tracing/snapshot echo 1 > /sys/kernel/tracing/snapshot
cat snapshot cat snapshot
config TRACER_SNAPSHOT_PER_CPU_SWAP 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 full swap (all buffers). If this is set, then the following is
allowed: 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 After which, only the tracing buffer for CPU 2 was swapped with
the main tracing buffer, and the other CPU buffers remain the same. 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 This tracer profiles all likely and unlikely macros
in the kernel. It will display the results in: 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 Note: this will add a significant overhead; only turn this
on if you need to profile the system's use of these macros. 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. taken in the kernel is recorded whether it hit or miss.
The results will be displayed in: 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. 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.: Tracing also is possible using the ftrace interface, e.g.:
echo 1 > /sys/block/sda/sda1/trace/enable echo 1 > /sys/block/sda/sda1/trace/enable
echo blk > /sys/kernel/debug/tracing/current_tracer echo blk > /sys/kernel/tracing/current_tracer
cat /sys/kernel/debug/tracing/trace_pipe cat /sys/kernel/tracing/trace_pipe
If unsure, say N. If unsure, say N.

2
kernel/trace/kprobe_event_gen_test.c
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@ -21,7 +21,7 @@
* Then: * Then:
* *
* # insmod kernel/trace/kprobe_event_gen_test.ko * # 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 * You should see many instances of the "gen_kprobe_test" and
* "gen_kretprobe_test" events in the trace buffer. * "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() ? "" : sched_clock_stable() ? "" :
"If you just came from a suspend/resume,\n" "If you just came from a suspend/resume,\n"
"please switch to the trace global clock:\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"); "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: * Then:
* *
* # insmod kernel/trace/synth_event_gen_test.ko * # 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 - * You should see several events in the trace buffer -
* "create_synth_test", "empty_synth_test", and several instances of * "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 * Note, make sure to allocate the snapshot with either
* a tracing_snapshot_alloc(), or by doing it manually * 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. * If the snapshot buffer is not allocated, it will stop tracing.
* Basically making a permanent snapshot. * Basically making a permanent snapshot.

4
samples/user_events/example.c
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@ -23,8 +23,8 @@
#endif #endif
/* Assumes debugfs is mounted */ /* Assumes debugfs is mounted */
const char *data_file = "/sys/kernel/debug/tracing/user_events_data"; const char *data_file = "/sys/kernel/tracing/user_events_data";
const char *status_file = "/sys/kernel/debug/tracing/user_events_status"; const char *status_file = "/sys/kernel/tracing/user_events_status";
static int event_status(long **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: Usage:
Be sure that you have CONFIG_FUNCTION_TRACER Be sure that you have CONFIG_FUNCTION_TRACER
# mount -t debugfs nodev /sys/kernel/debug # mount -t tracefs nodev /sys/kernel/tracing
# echo function > /sys/kernel/debug/tracing/current_tracer # echo function > /sys/kernel/tracing/current_tracer
$ cat /sys/kernel/debug/tracing/trace_pipe > ~/raw_trace_func $ cat /sys/kernel/tracing/trace_pipe > ~/raw_trace_func
Wait some times but not too much, the script is a bit slow. Wait some times but not too much, the script is a bit slow.
Break the pipe (Ctrl + Z) Break the pipe (Ctrl + Z)
$ scripts/tracing/draw_functrace.py < ~/raw_trace_func > draw_functrace $ 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" #include "tracing_path.h"
static char tracing_mnt[PATH_MAX] = "/sys/kernel/debug"; static char tracing_mnt[PATH_MAX] = "/sys/kernel/debug";
static char tracing_path[PATH_MAX] = "/sys/kernel/debug/tracing"; static char tracing_path[PATH_MAX] = "/sys/kernel/tracing";
static char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events"; static char tracing_events_path[PATH_MAX] = "/sys/kernel/tracing/events";
static void __tracing_path_set(const char *tracing, const char *mountpoint) 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 * Toss a coin to decide if we want to sleep before printing
* out the backtrace. The reason for this is that opening * 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 * hundreds of ms, where no latencies will be noted by the
* latency tracer. Thus by randomly sleeping we try to avoid * latency tracer. Thus by randomly sleeping we try to avoid
* missing traces systematically due to this. With this option * missing traces systematically due to this. With this option