Commit 07496eea authored by Ross Zwisler's avatar Ross Zwisler Committed by Michael S. Tsirkin
Browse files

tools/virtio: 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

A few spots in tools/virtio still refer to this older debugfs
path, so let's update them to avoid confusion.

Signed-off-by: default avatarRoss Zwisler <zwisler@google.com>
Message-Id: <20230215223350.2658616-6-zwisler@google.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarMukesh Ojha <quic_mojha@quicinc.com>
parent beee7fdb

tools/virtio/virtio-trace/README

+1 −1
Original line number Diff line number Diff line
@@ -95,7 +95,7 @@ Run 


1) Enable ftrace in the guest

 <Example>

	# echo 1 > /sys/kernel/debug/tracing/events/sched/enable

	# echo 1 > /sys/kernel/tracing/events/sched/enable



2) Run trace agent in the guest

 This agent must be operated as root.

tools/virtio/virtio-trace/trace-agent.c

+8 −4
Original line number Diff line number Diff line
@@ -18,8 +18,9 @@ 
#define PIPE_DEF_BUFS		16

#define PIPE_MIN_SIZE		(PAGE_SIZE*PIPE_DEF_BUFS)

#define PIPE_MAX_SIZE		(1024*1024)

#define READ_PATH_FMT	\

		"/sys/kernel/debug/tracing/per_cpu/cpu%d/trace_pipe_raw"

#define TRACEFS 		"/sys/kernel/tracing"

#define DEBUGFS 		"/sys/kernel/debug/tracing"

#define READ_PATH_FMT		"%s/per_cpu/cpu%d/trace_pipe_raw"

#define WRITE_PATH_FMT		"/dev/virtio-ports/trace-path-cpu%d"

#define CTL_PATH		"/dev/virtio-ports/agent-ctl-path"
@@ -120,9 +121,12 @@ static const char *make_path(int cpu_num, bool this_is_write_path) 
	if (this_is_write_path)

		/* write(output) path */

		ret = snprintf(buf, PATH_MAX, WRITE_PATH_FMT, cpu_num);

	else

	else {

		/* read(input) path */

		ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, cpu_num);

		ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, TRACEFS, cpu_num);

		if (ret > 0 && access(buf, F_OK) != 0)

			ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, DEBUGFS, cpu_num);

	}



	if (ret <= 0) {

		pr_err("Failed to generate %s path(CPU#%d):%d\n",