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SubjectRe: [PATCH] tools lib api fs: Store tracing mountpoint for better error message
2015-09-19 10:47 GMT-04:00 Jiri Olsa <jolsa@kernel.org>:
> 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'
> ...
>
> Link: http://lkml.kernel.org/n/tip-xw7mf64ie0svh6m449vbyh0m@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> 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:
> --
> 2.4.3
>

Reviewed-by: Raphaël Beamonte <raphael.beamonte@gmail.com>


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