[PATCH bpf-next 1/2] bpf: use canonical ftrace path

[PATCH bpf-next 1/2] bpf: use canonical ftrace path

[Ross Zwisler]

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 samples in the bpf code still refer to this older
debugfs path, so let's update them to avoid confusion.  There are a few
spots where the bpf code explicitly checks both tracefs and debugfs
(tools/bpf/bpftool/tracelog.c and tools/lib/api/fs/fs.c) and I've left
those alone so that the tools can continue to work with both paths.

Signed-off-by: Ross Zwisler <zwisler@google.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
---

[ Per Alexei's request, resending towards bpf-next ]

 include/uapi/linux/bpf.h            | 8 ++++----
 samples/bpf/cpustat_kern.c          | 4 ++--
 samples/bpf/hbm.c                   | 4 ++--
 samples/bpf/ibumad_kern.c           | 4 ++--
 samples/bpf/lwt_len_hist.sh         | 2 +-
 samples/bpf/offwaketime_kern.c      | 2 +-
 samples/bpf/task_fd_query_user.c    | 4 ++--
 samples/bpf/test_lwt_bpf.sh         | 2 +-
 samples/bpf/test_overhead_tp_kern.c | 4 ++--
 tools/include/uapi/linux/bpf.h      | 8 ++++----
 10 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 464ca3f01fe7..44387b31cbde 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1642,17 +1642,17 @@ union bpf_attr {
  * 	Description
  * 		This helper is a "printk()-like" facility for debugging. It
  * 		prints a message defined by format *fmt* (of size *fmt_size*)
- * 		to file *\/sys/kernel/debug/tracing/trace* from DebugFS, if
+ * 		to file *\/sys/kernel/tracing/trace* from TraceFS, if
  * 		available. It can take up to three additional **u64**
  * 		arguments (as an eBPF helpers, the total number of arguments is
  * 		limited to five).
  *
  * 		Each time the helper is called, it appends a line to the trace.
- * 		Lines are discarded while *\/sys/kernel/debug/tracing/trace* is
- * 		open, use *\/sys/kernel/debug/tracing/trace_pipe* to avoid this.
+ * 		Lines are discarded while *\/sys/kernel/tracing/trace* is
+ * 		open, use *\/sys/kernel/tracing/trace_pipe* to avoid this.
  * 		The format of the trace is customizable, and the exact output
  * 		one will get depends on the options set in
- * 		*\/sys/kernel/debug/tracing/trace_options* (see also the
+ * 		*\/sys/kernel/tracing/trace_options* (see also the
  * 		*README* file under the same directory). However, it usually
  * 		defaults to something like:
  *
diff --git a/samples/bpf/cpustat_kern.c b/samples/bpf/cpustat_kern.c
index 5aefd19cdfa1..944f13fe164a 100644
--- a/samples/bpf/cpustat_kern.c
+++ b/samples/bpf/cpustat_kern.c
@@ -76,8 +76,8 @@ struct {
 
 /*
  * The trace events for cpu_idle and cpu_frequency are taken from:
- * /sys/kernel/debug/tracing/events/power/cpu_idle/format
- * /sys/kernel/debug/tracing/events/power/cpu_frequency/format
+ * /sys/kernel/tracing/events/power/cpu_idle/format
+ * /sys/kernel/tracing/events/power/cpu_frequency/format
  *
  * These two events have same format, so define one common structure.
  */
diff --git a/samples/bpf/hbm.c b/samples/bpf/hbm.c
index 516fbac28b71..ff58ec43f56a 100644
--- a/samples/bpf/hbm.c
+++ b/samples/bpf/hbm.c
@@ -65,7 +65,7 @@ static void Usage(void);
 static void read_trace_pipe2(void);
 static void do_error(char *msg, bool errno_flag);
 
-#define DEBUGFS "/sys/kernel/debug/tracing/"
+#define TRACEFS "/sys/kernel/tracing/"
 
 static struct bpf_program *bpf_prog;
 static struct bpf_object *obj;
@@ -77,7 +77,7 @@ static void read_trace_pipe2(void)
 	FILE *outf;
 	char *outFname = "hbm_out.log";
 
-	trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
+	trace_fd = open(TRACEFS "trace_pipe", O_RDONLY, 0);
 	if (trace_fd < 0) {
 		printf("Error opening trace_pipe\n");
 		return;
diff --git a/samples/bpf/ibumad_kern.c b/samples/bpf/ibumad_kern.c
index 9b193231024a..f07474c72525 100644
--- a/samples/bpf/ibumad_kern.c
+++ b/samples/bpf/ibumad_kern.c
@@ -39,8 +39,8 @@ struct {
 /* Taken from the current format defined in
  * include/trace/events/ib_umad.h
  * and
- * /sys/kernel/debug/tracing/events/ib_umad/ib_umad_read/format
- * /sys/kernel/debug/tracing/events/ib_umad/ib_umad_write/format
+ * /sys/kernel/tracing/events/ib_umad/ib_umad_read/format
+ * /sys/kernel/tracing/events/ib_umad/ib_umad_write/format
  */
 struct ib_umad_rw_args {
 	u64 pad;
diff --git a/samples/bpf/lwt_len_hist.sh b/samples/bpf/lwt_len_hist.sh
index 0eda9754f50b..11fa0a087db6 100755
--- a/samples/bpf/lwt_len_hist.sh
+++ b/samples/bpf/lwt_len_hist.sh
@@ -5,7 +5,7 @@ NS1=lwt_ns1
 VETH0=tst_lwt1a
 VETH1=tst_lwt1b
 
-TRACE_ROOT=/sys/kernel/debug/tracing
+TRACE_ROOT=/sys/kernel/tracing
 
 function cleanup {
 	# To reset saved histogram, remove pinned map
diff --git a/samples/bpf/offwaketime_kern.c b/samples/bpf/offwaketime_kern.c
index eb4d94742e6b..23f12b47e9e5 100644
--- a/samples/bpf/offwaketime_kern.c
+++ b/samples/bpf/offwaketime_kern.c
@@ -110,7 +110,7 @@ static inline int update_counts(void *ctx, u32 pid, u64 delta)
 }
 
 #if 1
-/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
+/* taken from /sys/kernel/tracing/events/sched/sched_switch/format */
 struct sched_switch_args {
 	unsigned long long pad;
 	char prev_comm[TASK_COMM_LEN];
diff --git a/samples/bpf/task_fd_query_user.c b/samples/bpf/task_fd_query_user.c
index a33d74bd3a4b..1e61f2180470 100644
--- a/samples/bpf/task_fd_query_user.c
+++ b/samples/bpf/task_fd_query_user.c
@@ -235,7 +235,7 @@ static int test_debug_fs_uprobe(char *binary_path, long offset, bool is_return)
 	struct bpf_link *link;
 	ssize_t bytes;
 
-	snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/%s_events",
+	snprintf(buf, sizeof(buf), "/sys/kernel/tracing/%s_events",
 		 event_type);
 	kfd = open(buf, O_WRONLY | O_TRUNC, 0);
 	CHECK_PERROR_RET(kfd < 0);
@@ -252,7 +252,7 @@ static int test_debug_fs_uprobe(char *binary_path, long offset, bool is_return)
 	close(kfd);
 	kfd = -1;
 
-	snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%ss/%s/id",
+	snprintf(buf, sizeof(buf), "/sys/kernel/tracing/events/%ss/%s/id",
 		 event_type, event_alias);
 	efd = open(buf, O_RDONLY, 0);
 	CHECK_PERROR_RET(efd < 0);
diff --git a/samples/bpf/test_lwt_bpf.sh b/samples/bpf/test_lwt_bpf.sh
index 65a976058dd3..db5691e6637f 100755
--- a/samples/bpf/test_lwt_bpf.sh
+++ b/samples/bpf/test_lwt_bpf.sh
@@ -19,7 +19,7 @@ IPVETH3="192.168.111.2"
 
 IP_LOCAL="192.168.99.1"
 
-TRACE_ROOT=/sys/kernel/debug/tracing
+TRACE_ROOT=/sys/kernel/tracing
 
 function lookup_mac()
 {
diff --git a/samples/bpf/test_overhead_tp_kern.c b/samples/bpf/test_overhead_tp_kern.c
index 80edadacb692..a1d53b0d8476 100644
--- a/samples/bpf/test_overhead_tp_kern.c
+++ b/samples/bpf/test_overhead_tp_kern.c
@@ -8,7 +8,7 @@
 #include <uapi/linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 
-/* from /sys/kernel/debug/tracing/events/task/task_rename/format */
+/* from /sys/kernel/tracing/events/task/task_rename/format */
 struct task_rename {
 	__u64 pad;
 	__u32 pid;
@@ -22,7 +22,7 @@ int prog(struct task_rename *ctx)
 	return 0;
 }
 
-/* from /sys/kernel/debug/tracing/events/random/urandom_read/format */
+/* from /sys/kernel/tracing/events/random/urandom_read/format */
 struct urandom_read {
 	__u64 pad;
 	int got_bits;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 464ca3f01fe7..44387b31cbde 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1642,17 +1642,17 @@ union bpf_attr {
  * 	Description
  * 		This helper is a "printk()-like" facility for debugging. It
  * 		prints a message defined by format *fmt* (of size *fmt_size*)
- * 		to file *\/sys/kernel/debug/tracing/trace* from DebugFS, if
+ * 		to file *\/sys/kernel/tracing/trace* from TraceFS, if
  * 		available. It can take up to three additional **u64**
  * 		arguments (as an eBPF helpers, the total number of arguments is
  * 		limited to five).
  *
  * 		Each time the helper is called, it appends a line to the trace.
- * 		Lines are discarded while *\/sys/kernel/debug/tracing/trace* is
- * 		open, use *\/sys/kernel/debug/tracing/trace_pipe* to avoid this.
+ * 		Lines are discarded while *\/sys/kernel/tracing/trace* is
+ * 		open, use *\/sys/kernel/tracing/trace_pipe* to avoid this.
  * 		The format of the trace is customizable, and the exact output
  * 		one will get depends on the options set in
- * 		*\/sys/kernel/debug/tracing/trace_options* (see also the
+ * 		*\/sys/kernel/tracing/trace_options* (see also the
  * 		*README* file under the same directory). However, it usually
  * 		defaults to something like:
  *
-- 
2.39.1.581.gbfd45094c4-goog

[PATCH bpf-next 2/2] selftests/bpf: use canonical ftrace path

[Ross Zwisler]

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 tests in the bpf selftest code still refer to this older debugfs
path, so let's update them to avoid confusion.

Signed-off-by: Ross Zwisler <zwisler@google.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
---

[ Per Alexei's request, resending towards bpf-next ]

 tools/testing/selftests/bpf/get_cgroup_id_user.c          | 2 +-
 .../testing/selftests/bpf/prog_tests/kprobe_multi_test.c  | 2 +-
 tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c | 2 +-
 tools/testing/selftests/bpf/prog_tests/tp_attach_query.c  | 2 +-
 tools/testing/selftests/bpf/prog_tests/trace_printk.c     | 2 +-
 tools/testing/selftests/bpf/prog_tests/trace_vprintk.c    | 2 +-
 tools/testing/selftests/bpf/progs/test_stacktrace_map.c   | 2 +-
 tools/testing/selftests/bpf/progs/test_tracepoint.c       | 2 +-
 tools/testing/selftests/bpf/test_ftrace.sh                | 2 +-
 tools/testing/selftests/bpf/test_tunnel.sh                | 8 ++++----
 tools/testing/selftests/bpf/trace_helpers.c               | 4 ++--
 11 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/tools/testing/selftests/bpf/get_cgroup_id_user.c b/tools/testing/selftests/bpf/get_cgroup_id_user.c
index 156743cf5870..478e080128be 100644
--- a/tools/testing/selftests/bpf/get_cgroup_id_user.c
+++ b/tools/testing/selftests/bpf/get_cgroup_id_user.c
@@ -87,7 +87,7 @@ int main(int argc, char **argv)
 	bpf_map_update_elem(pidmap_fd, &key, &pid, 0);
 
 	snprintf(buf, sizeof(buf),
-		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
+		 "/sys/kernel/tracing/events/%s/id", probe_name);
 	efd = open(buf, O_RDONLY, 0);
 	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
 		goto close_prog;
diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
index c6f37e825f11..6f0f2d8984db 100644
--- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
@@ -338,7 +338,7 @@ static int get_syms(char ***symsp, size_t *cntp)
 	 * Filtering out duplicates by using hashmap__add, which won't
 	 * add existing entry.
 	 */
-	f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
+	f = fopen("/sys/kernel/tracing/available_filter_functions", "r");
 	if (!f)
 		return -EINVAL;
 
diff --git a/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c b/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
index c717741bf8b6..6d70559fc19b 100644
--- a/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
+++ b/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
@@ -18,7 +18,7 @@ static void test_task_fd_query_tp_core(const char *probe_name,
 		goto close_prog;
 
 	snprintf(buf, sizeof(buf),
-		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
+		 "/sys/kernel/tracing/events/%s/id", probe_name);
 	efd = open(buf, O_RDONLY, 0);
 	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
 		goto close_prog;
diff --git a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
index a479080533db..4308e3a828d8 100644
--- a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
+++ b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
@@ -17,7 +17,7 @@ void serial_test_tp_attach_query(void)
 		obj[i] = NULL;
 
 	snprintf(buf, sizeof(buf),
-		 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");
+		 "/sys/kernel/tracing/events/sched/sched_switch/id");
 	efd = open(buf, O_RDONLY, 0);
 	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
 		return;
diff --git a/tools/testing/selftests/bpf/prog_tests/trace_printk.c b/tools/testing/selftests/bpf/prog_tests/trace_printk.c
index cade7f12315f..ff50a928cb98 100644
--- a/tools/testing/selftests/bpf/prog_tests/trace_printk.c
+++ b/tools/testing/selftests/bpf/prog_tests/trace_printk.c
@@ -5,7 +5,7 @@
 
 #include "trace_printk.lskel.h"
 
-#define TRACEBUF	"/sys/kernel/debug/tracing/trace_pipe"
+#define TRACEBUF	"/sys/kernel/tracing/trace_pipe"
 #define SEARCHMSG	"testing,testing"
 
 void serial_test_trace_printk(void)
diff --git a/tools/testing/selftests/bpf/prog_tests/trace_vprintk.c b/tools/testing/selftests/bpf/prog_tests/trace_vprintk.c
index 7a4e313e8558..e568d7f247ec 100644
--- a/tools/testing/selftests/bpf/prog_tests/trace_vprintk.c
+++ b/tools/testing/selftests/bpf/prog_tests/trace_vprintk.c
@@ -5,7 +5,7 @@
 
 #include "trace_vprintk.lskel.h"
 
-#define TRACEBUF	"/sys/kernel/debug/tracing/trace_pipe"
+#define TRACEBUF	"/sys/kernel/tracing/trace_pipe"
 #define SEARCHMSG	"1,2,3,4,5,6,7,8,9,10"
 
 void serial_test_trace_vprintk(void)
diff --git a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c
index 728dbd39eff0..47568007b668 100644
--- a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c
+++ b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c
@@ -38,7 +38,7 @@ struct {
 	__type(value, stack_trace_t);
 } stack_amap SEC(".maps");
 
-/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
+/* taken from /sys/kernel/tracing/events/sched/sched_switch/format */
 struct sched_switch_args {
 	unsigned long long pad;
 	char prev_comm[TASK_COMM_LEN];
diff --git a/tools/testing/selftests/bpf/progs/test_tracepoint.c b/tools/testing/selftests/bpf/progs/test_tracepoint.c
index 43bd7a20cc50..4cb8bbb6a320 100644
--- a/tools/testing/selftests/bpf/progs/test_tracepoint.c
+++ b/tools/testing/selftests/bpf/progs/test_tracepoint.c
@@ -4,7 +4,7 @@
 #include <vmlinux.h>
 #include <bpf/bpf_helpers.h>
 
-/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
+/* taken from /sys/kernel/tracing/events/sched/sched_switch/format */
 struct sched_switch_args {
 	unsigned long long pad;
 	char prev_comm[TASK_COMM_LEN];
diff --git a/tools/testing/selftests/bpf/test_ftrace.sh b/tools/testing/selftests/bpf/test_ftrace.sh
index 20de7bb873bc..e3e2328a1b65 100755
--- a/tools/testing/selftests/bpf/test_ftrace.sh
+++ b/tools/testing/selftests/bpf/test_ftrace.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-TR=/sys/kernel/debug/tracing/
+TR=/sys/kernel/tracing/
 clear_trace() { # reset trace output
     echo > $TR/trace
 }
diff --git a/tools/testing/selftests/bpf/test_tunnel.sh b/tools/testing/selftests/bpf/test_tunnel.sh
index 2eaedc1d9ed3..bbbd242f7cef 100755
--- a/tools/testing/selftests/bpf/test_tunnel.sh
+++ b/tools/testing/selftests/bpf/test_tunnel.sh
@@ -543,7 +543,7 @@ setup_xfrm_tunnel()
 test_xfrm_tunnel()
 {
 	config_device
-	> /sys/kernel/debug/tracing/trace
+	> /sys/kernel/tracing/trace
 	setup_xfrm_tunnel
 	mkdir -p ${BPF_PIN_TUNNEL_DIR}
 	bpftool prog loadall ${BPF_FILE} ${BPF_PIN_TUNNEL_DIR}
@@ -552,11 +552,11 @@ test_xfrm_tunnel()
 		${BPF_PIN_TUNNEL_DIR}/xfrm_get_state
 	ip netns exec at_ns0 ping $PING_ARG 10.1.1.200
 	sleep 1
-	grep "reqid 1" /sys/kernel/debug/tracing/trace
+	grep "reqid 1" /sys/kernel/tracing/trace
 	check_err $?
-	grep "spi 0x1" /sys/kernel/debug/tracing/trace
+	grep "spi 0x1" /sys/kernel/tracing/trace
 	check_err $?
-	grep "remote ip 0xac100164" /sys/kernel/debug/tracing/trace
+	grep "remote ip 0xac100164" /sys/kernel/tracing/trace
 	check_err $?
 	cleanup
 
diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index 09a16a77bae4..d2816aa35a9b 100644
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -12,7 +12,7 @@
 #include <sys/mman.h>
 #include "trace_helpers.h"
 
-#define DEBUGFS "/sys/kernel/debug/tracing/"
+#define TRACEFS "/sys/kernel/tracing/"
 
 #define MAX_SYMS 300000
 static struct ksym syms[MAX_SYMS];
@@ -136,7 +136,7 @@ void read_trace_pipe(void)
 {
 	int trace_fd;
 
-	trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
+	trace_fd = open(TRACEFS "trace_pipe", O_RDONLY, 0);
 	if (trace_fd < 0)
 		return;
 
-- 
2.39.1.581.gbfd45094c4-goog

Re: [PATCH bpf-next 1/2] bpf: use canonical ftrace path

[Stanislav Fomichev]

On 02/13, Ross Zwisler wrote:
> 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 samples in the bpf code still refer to this older
> debugfs path, so let's update them to avoid confusion.  There are a few
> spots where the bpf code explicitly checks both tracefs and debugfs
> (tools/bpf/bpftool/tracelog.c and tools/lib/api/fs/fs.c) and I've left
> those alone so that the tools can continue to work with both paths.

Doesn't seem to apply cleanly to bpf-next?

https://github.com/kernel-patches/bpf/pull/4584

> Signed-off-by: Ross Zwisler <zwisler@google.com>
> Acked-by: Michael S. Tsirkin <mst@redhat.com>
> ---

> [ Per Alexei's request, resending towards bpf-next ]

>   include/uapi/linux/bpf.h            | 8 ++++----
>   samples/bpf/cpustat_kern.c          | 4 ++--
>   samples/bpf/hbm.c                   | 4 ++--
>   samples/bpf/ibumad_kern.c           | 4 ++--
>   samples/bpf/lwt_len_hist.sh         | 2 +-
>   samples/bpf/offwaketime_kern.c      | 2 +-
>   samples/bpf/task_fd_query_user.c    | 4 ++--
>   samples/bpf/test_lwt_bpf.sh         | 2 +-
>   samples/bpf/test_overhead_tp_kern.c | 4 ++--
>   tools/include/uapi/linux/bpf.h      | 8 ++++----
>   10 files changed, 21 insertions(+), 21 deletions(-)

> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 464ca3f01fe7..44387b31cbde 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -1642,17 +1642,17 @@ union bpf_attr {
>    * 	Description
>    * 		This helper is a "printk()-like" facility for debugging. It
>    * 		prints a message defined by format *fmt* (of size *fmt_size*)
> - * 		to file *\/sys/kernel/debug/tracing/trace* from DebugFS, if
> + * 		to file *\/sys/kernel/tracing/trace* from TraceFS, if
>    * 		available. It can take up to three additional **u64**
>    * 		arguments (as an eBPF helpers, the total number of arguments is
>    * 		limited to five).
>    *
>    * 		Each time the helper is called, it appends a line to the trace.
> - * 		Lines are discarded while *\/sys/kernel/debug/tracing/trace* is
> - * 		open, use *\/sys/kernel/debug/tracing/trace_pipe* to avoid this.
> + * 		Lines are discarded while *\/sys/kernel/tracing/trace* is
> + * 		open, use *\/sys/kernel/tracing/trace_pipe* to avoid this.
>    * 		The format of the trace is customizable, and the exact output
>    * 		one will get depends on the options set in
> - * 		*\/sys/kernel/debug/tracing/trace_options* (see also the
> + * 		*\/sys/kernel/tracing/trace_options* (see also the
>    * 		*README* file under the same directory). However, it usually
>    * 		defaults to something like:
>    *
> diff --git a/samples/bpf/cpustat_kern.c b/samples/bpf/cpustat_kern.c
> index 5aefd19cdfa1..944f13fe164a 100644
> --- a/samples/bpf/cpustat_kern.c
> +++ b/samples/bpf/cpustat_kern.c
> @@ -76,8 +76,8 @@ struct {

>   /*
>    * The trace events for cpu_idle and cpu_frequency are taken from:
> - * /sys/kernel/debug/tracing/events/power/cpu_idle/format
> - * /sys/kernel/debug/tracing/events/power/cpu_frequency/format
> + * /sys/kernel/tracing/events/power/cpu_idle/format
> + * /sys/kernel/tracing/events/power/cpu_frequency/format
>    *
>    * These two events have same format, so define one common structure.
>    */
> diff --git a/samples/bpf/hbm.c b/samples/bpf/hbm.c
> index 516fbac28b71..ff58ec43f56a 100644
> --- a/samples/bpf/hbm.c
> +++ b/samples/bpf/hbm.c
> @@ -65,7 +65,7 @@ static void Usage(void);
>   static void read_trace_pipe2(void);
>   static void do_error(char *msg, bool errno_flag);

> -#define DEBUGFS "/sys/kernel/debug/tracing/"
> +#define TRACEFS "/sys/kernel/tracing/"

>   static struct bpf_program *bpf_prog;
>   static struct bpf_object *obj;
> @@ -77,7 +77,7 @@ static void read_trace_pipe2(void)
>   	FILE *outf;
>   	char *outFname = "hbm_out.log";

> -	trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
> +	trace_fd = open(TRACEFS "trace_pipe", O_RDONLY, 0);
>   	if (trace_fd < 0) {
>   		printf("Error opening trace_pipe\n");
>   		return;
> diff --git a/samples/bpf/ibumad_kern.c b/samples/bpf/ibumad_kern.c
> index 9b193231024a..f07474c72525 100644
> --- a/samples/bpf/ibumad_kern.c
> +++ b/samples/bpf/ibumad_kern.c
> @@ -39,8 +39,8 @@ struct {
>   /* Taken from the current format defined in
>    * include/trace/events/ib_umad.h
>    * and
> - * /sys/kernel/debug/tracing/events/ib_umad/ib_umad_read/format
> - * /sys/kernel/debug/tracing/events/ib_umad/ib_umad_write/format
> + * /sys/kernel/tracing/events/ib_umad/ib_umad_read/format
> + * /sys/kernel/tracing/events/ib_umad/ib_umad_write/format
>    */
>   struct ib_umad_rw_args {
>   	u64 pad;
> diff --git a/samples/bpf/lwt_len_hist.sh b/samples/bpf/lwt_len_hist.sh
> index 0eda9754f50b..11fa0a087db6 100755
> --- a/samples/bpf/lwt_len_hist.sh
> +++ b/samples/bpf/lwt_len_hist.sh
> @@ -5,7 +5,7 @@ NS1=lwt_ns1
>   VETH0=tst_lwt1a
>   VETH1=tst_lwt1b

> -TRACE_ROOT=/sys/kernel/debug/tracing
> +TRACE_ROOT=/sys/kernel/tracing

>   function cleanup {
>   	# To reset saved histogram, remove pinned map
> diff --git a/samples/bpf/offwaketime_kern.c  
> b/samples/bpf/offwaketime_kern.c
> index eb4d94742e6b..23f12b47e9e5 100644
> --- a/samples/bpf/offwaketime_kern.c
> +++ b/samples/bpf/offwaketime_kern.c
> @@ -110,7 +110,7 @@ static inline int update_counts(void *ctx, u32 pid,  
> u64 delta)
>   }

>   #if 1
> -/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format  
> */
> +/* taken from /sys/kernel/tracing/events/sched/sched_switch/format */
>   struct sched_switch_args {
>   	unsigned long long pad;
>   	char prev_comm[TASK_COMM_LEN];
> diff --git a/samples/bpf/task_fd_query_user.c  
> b/samples/bpf/task_fd_query_user.c
> index a33d74bd3a4b..1e61f2180470 100644
> --- a/samples/bpf/task_fd_query_user.c
> +++ b/samples/bpf/task_fd_query_user.c
> @@ -235,7 +235,7 @@ static int test_debug_fs_uprobe(char *binary_path,  
> long offset, bool is_return)
>   	struct bpf_link *link;
>   	ssize_t bytes;

> -	snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/%s_events",
> +	snprintf(buf, sizeof(buf), "/sys/kernel/tracing/%s_events",
>   		 event_type);
>   	kfd = open(buf, O_WRONLY | O_TRUNC, 0);
>   	CHECK_PERROR_RET(kfd < 0);
> @@ -252,7 +252,7 @@ static int test_debug_fs_uprobe(char *binary_path,  
> long offset, bool is_return)
>   	close(kfd);
>   	kfd = -1;

> -	snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%ss/%s/id",
> +	snprintf(buf, sizeof(buf), "/sys/kernel/tracing/events/%ss/%s/id",
>   		 event_type, event_alias);
>   	efd = open(buf, O_RDONLY, 0);
>   	CHECK_PERROR_RET(efd < 0);
> diff --git a/samples/bpf/test_lwt_bpf.sh b/samples/bpf/test_lwt_bpf.sh
> index 65a976058dd3..db5691e6637f 100755
> --- a/samples/bpf/test_lwt_bpf.sh
> +++ b/samples/bpf/test_lwt_bpf.sh
> @@ -19,7 +19,7 @@ IPVETH3="192.168.111.2"

>   IP_LOCAL="192.168.99.1"

> -TRACE_ROOT=/sys/kernel/debug/tracing
> +TRACE_ROOT=/sys/kernel/tracing

>   function lookup_mac()
>   {
> diff --git a/samples/bpf/test_overhead_tp_kern.c  
> b/samples/bpf/test_overhead_tp_kern.c
> index 80edadacb692..a1d53b0d8476 100644
> --- a/samples/bpf/test_overhead_tp_kern.c
> +++ b/samples/bpf/test_overhead_tp_kern.c
> @@ -8,7 +8,7 @@
>   #include <uapi/linux/bpf.h>
>   #include <bpf/bpf_helpers.h>

> -/* from /sys/kernel/debug/tracing/events/task/task_rename/format */
> +/* from /sys/kernel/tracing/events/task/task_rename/format */
>   struct task_rename {
>   	__u64 pad;
>   	__u32 pid;
> @@ -22,7 +22,7 @@ int prog(struct task_rename *ctx)
>   	return 0;
>   }

> -/* from /sys/kernel/debug/tracing/events/random/urandom_read/format */
> +/* from /sys/kernel/tracing/events/random/urandom_read/format */
>   struct urandom_read {
>   	__u64 pad;
>   	int got_bits;
> diff --git a/tools/include/uapi/linux/bpf.h  
> b/tools/include/uapi/linux/bpf.h
> index 464ca3f01fe7..44387b31cbde 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -1642,17 +1642,17 @@ union bpf_attr {
>    * 	Description
>    * 		This helper is a "printk()-like" facility for debugging. It
>    * 		prints a message defined by format *fmt* (of size *fmt_size*)
> - * 		to file *\/sys/kernel/debug/tracing/trace* from DebugFS, if
> + * 		to file *\/sys/kernel/tracing/trace* from TraceFS, if
>    * 		available. It can take up to three additional **u64**
>    * 		arguments (as an eBPF helpers, the total number of arguments is
>    * 		limited to five).
>    *
>    * 		Each time the helper is called, it appends a line to the trace.
> - * 		Lines are discarded while *\/sys/kernel/debug/tracing/trace* is
> - * 		open, use *\/sys/kernel/debug/tracing/trace_pipe* to avoid this.
> + * 		Lines are discarded while *\/sys/kernel/tracing/trace* is
> + * 		open, use *\/sys/kernel/tracing/trace_pipe* to avoid this.
>    * 		The format of the trace is customizable, and the exact output
>    * 		one will get depends on the options set in
> - * 		*\/sys/kernel/debug/tracing/trace_options* (see also the
> + * 		*\/sys/kernel/tracing/trace_options* (see also the
>    * 		*README* file under the same directory). However, it usually
>    * 		defaults to something like:
>    *
> --
> 2.39.1.581.gbfd45094c4-goog

Re: [PATCH bpf-next 1/2] bpf: use canonical ftrace path

[Ross Zwisler]

On Mon, Feb 13, 2023 at 06:57:16PM -0800, Stanislav Fomichev wrote:
> On 02/13, Ross Zwisler wrote:
> > 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 samples in the bpf code still refer to this older
> > debugfs path, so let's update them to avoid confusion.  There are a few
> > spots where the bpf code explicitly checks both tracefs and debugfs
> > (tools/bpf/bpftool/tracelog.c and tools/lib/api/fs/fs.c) and I've left
> > those alone so that the tools can continue to work with both paths.
> 
> Doesn't seem to apply cleanly to bpf-next?
> 
> https://github.com/kernel-patches/bpf/pull/4584

Oh, apologies, I was using Linus's master branch as my baseline.
I'll send out a v2.