Commit ab85785a authored Jul 06, 2015 by Arnaldo Carvalho de Melo

tools lib api debugfs: Check for tracefs when reporting errors

Now that we have two mountpoints, one for debugfs and another, for
tracefs, we end up needing to check permissions for both, so, on
a system with default config we were always asking the user to
check the permission of the debugfs mountpoint, even when it was
already sufficient. Fix it.

E.g.:

  $ trace -e nanosleep usleep 1
  Error: No permissions to read /sys/kernel/debug/tracing/events/raw_syscalls/sys_(enter|exit)
  Hint:  Try 'sudo mount -o remount,mode=755 /sys/kernel/debug'

  $ sudo mount -o remount,mode=755 /sys/kernel/debug
  $ trace -e nanosleep usleep 1
  Error: No permissions to read /sys/kernel/debug/tracing/events/raw_syscalls/sys_(enter|exit)
  Hint:  Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing'

  $ sudo mount -o remount,mode=755 /sys/kernel/debug/tracing
  $ trace -e nanosleep usleep 1
     0.326 ( 0.061 ms): usleep/11961 nanosleep(rqtp: 0x7ffef1081c50) = 0
  $

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/n/tip-0viljeuhc7q84ic8kobsna43@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 3abebc55

tools/lib/api/fs/debugfs.c

+13 −2

Original line number	Diff line number	Diff line
		@@ -12,6 +12,7 @@
		#include <linux/kernel.h>

		#include "debugfs.h"
		#include "tracefs.h"

		#ifndef DEBUGFS_DEFAULT_PATH
		#define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug"
		@@ -94,11 +95,21 @@ int debugfs__strerror_open(int err, char buf, size_t size, const char filename
		"Hint:\tIs the debugfs filesystem mounted?\n"
		"Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
		break;
		case EACCES:
		case EACCES: {
		const char *mountpoint = debugfs_mountpoint;

		if (!access(debugfs_mountpoint, R_OK) && strncmp(filename, "tracing/", 8) == 0) {
		const char *tracefs_mntpoint = tracefs_find_mountpoint();

		if (tracefs_mntpoint)
		mountpoint = tracefs_mntpoint;
		}

		snprintf(buf, size,
		"Error:\tNo permissions to read %s/%s\n"
		"Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
		debugfs_mountpoint, filename, debugfs_mountpoint);
		debugfs_mountpoint, filename, mountpoint);
		}
		break;
		default:
		snprintf(buf, size, "%s", strerror_r(err, sbuf, sizeof(sbuf)));