From dc240c5dc2a02e335c5bcb50ad3a1274818c8609 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Sat, 19 Sep 2015 16:47:07 +0200 Subject: [PATCH] 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: Jiri Olsa Cc: David Ahern Cc: Matt Fleming Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Raphael Beamonte Link: http://lkml.kernel.org/r/1442674027-19427-1-git-send-email-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/api/fs/tracing_path.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) diff --git a/tools/lib/api/fs/tracing_path.c b/tools/lib/api/fs/tracing_path.c index 38aca2dd1946..0406a7d5c891 100644 --- a/tools/lib/api/fs/tracing_path.c +++ b/tools/lib/api/fs/tracing_path.c @@ -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: -- 2.20.1