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

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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@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---

[ 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




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