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Commit dc240c5d authored by Jiri Olsa's avatar Jiri Olsa Committed by Arnaldo Carvalho de Melo
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tools lib api fs: Store tracing mountpoint for better error message 



Storing the actual tracing path mountpoint to display correct
error message hint ('Hint:' line). The error hint rediscovers
mountpoints, but it could be different from what we actually
used in tracing path.

Before we'd display debugfs mount even though tracefs was used:
  $ perf record -e sched:sched_krava ls
  event syntax error: 'sched:sched_krava'
                       \___ can't access trace events

  Error:  No permissions to read /sys/kernel/debug/tracing/events/sched/sched_krava
  Hint:   Try 'sudo mount -o remount,mode=755 /sys/kernel/debug'
  ...

After this change, correct mountpoint is displayed:
  $ perf record -e sched:sched_krava ls
  event syntax error: 'sched:sched_krava'
                       \___ can't access trace events

  Error:  No permissions to read /sys/kernel/debug/tracing/events/sched/sched_krava
  Hint:   Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing'
  ...

Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Raphael Beamonte <raphael.beamonte@gmail.com>
Link: http://lkml.kernel.org/r/1442674027-19427-1-git-send-email-jolsa@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent ab9c2bdc

tools/lib/api/fs/tracing_path.c

+3 −10
Original line number Diff line number Diff line
@@ -12,12 +12,14 @@ 
#include "tracing_path.h"





char tracing_mnt[PATH_MAX + 1]         = "/sys/kernel/debug";

char tracing_path[PATH_MAX + 1]        = "/sys/kernel/debug/tracing";

char tracing_events_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing/events";





static void __tracing_path_set(const char *tracing, const char *mountpoint)

{

	snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);

	snprintf(tracing_path, sizeof(tracing_path), "%s/%s",

		 mountpoint, tracing);

	snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
@@ -109,19 +111,10 @@ static int strerror_open(int err, char *buf, size_t size, const char *filename) 
			 "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");

		break;

	case EACCES: {

		const char *mountpoint = debugfs__mountpoint();



		if (!access(mountpoint, R_OK) && strncmp(filename, "tracing/", 8) == 0) {

			const char *tracefs_mntpoint = tracefs__mountpoint();



			if (tracefs_mntpoint)

				mountpoint = tracefs__mountpoint();

		}



		snprintf(buf, size,

			 "Error:\tNo permissions to read %s/%s\n"

			 "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",

			 tracing_events_path, filename, mountpoint);

			 tracing_events_path, filename, tracing_mnt);

	}

		break;

	default: