bpf: 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 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>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20230313205628.1058720-2-zwisler@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index d8c534e..13129df 100644 (file)
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1647,17 +1647,17 @@ 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 5aefd19..944f13f 100644 (file)
--- 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 516fbac..ff58ec4 100644 (file)
--- 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 9b19323..f07474c 100644 (file)
--- 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 7078bfc..381b2c6 100755 (executable)
--- 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
 BPF_PROG=lwt_len_hist.bpf.o
-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 eb4d947..23f12b4 100644 (file)
--- 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 a33d74b..1e61f21 100644 (file)
--- 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 2e9f512..0bf2d0f 100755 (executable)
--- a/samples/bpf/test_lwt_bpf.sh
+++ b/samples/bpf/test_lwt_bpf.sh
@@ -21,7 +21,7 @@ IP_LOCAL="192.168.99.1"
 
 PROG_SRC="test_lwt_bpf.c"
 BPF_PROG="test_lwt_bpf.o"
-TRACE_ROOT=/sys/kernel/debug/tracing
+TRACE_ROOT=/sys/kernel/tracing
 CONTEXT_INFO=$(cat ${TRACE_ROOT}/trace_options | grep context)
 
 function lookup_mac()

diff --git a/samples/bpf/test_overhead_tp.bpf.c b/samples/bpf/test_overhead_tp.bpf.c
index 67cab38..8b49832 100644 (file)
--- a/samples/bpf/test_overhead_tp.bpf.c
+++ b/samples/bpf/test_overhead_tp.bpf.c
@@ -7,7 +7,7 @@
 #include "vmlinux.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;
@@ -21,7 +21,7 @@ int prog(struct task_rename *ctx)
        return 0;
 }
 
-/* from /sys/kernel/debug/tracing/events/fib/fib_table_lookup/format */
+/* from /sys/kernel/tracing/events/fib/fib_table_lookup/format */
 struct fib_table_lookup {
        __u64 pad;
        __u32 tb_id;

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index d8c534e..13129df 100644 (file)
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1647,17 +1647,17 @@ 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:
  *