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[PATCH 04/39] tools lib api fs: Store tracing mountpoint for better error message

From Arnaldo Carvalho de Melo <acme@kernel.org>
Newsgroups linux.kernel
Subject [PATCH 04/39] tools lib api fs: Store tracing mountpoint for better error message
Date 2015-09-28 23:20 +0200
Message-ID <qdO05-2Tc-67@gated-at.bofh.it> (permalink)
References <qdNQm-2GE-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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From: 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'
  ...

Signed-off-by: Jiri 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: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 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:
-- 
2.1.0

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Thread

[GIT PULL 00/39] perf/core improvements and fixes Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:10 +0200
  [PATCH 06/39] tools build: Add test for missing include Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:10 +0200
  [PATCH 02/39] perf hists browser: Use the map to determine if a DSO is being used as a kernel Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:10 +0200
  [PATCH 20/39] perf report: Adjust sample type validation for synthesized branch stacks Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:10 +0200
  [PATCH 37/39] perf tools: Show proper error message for wrong terms of hw/sw events Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 31/39] perf evlist: Add perf_evlist__id2evsel_strict() Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 15/39] perf intel-pt: Make logging slightly more efficient Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 26/39] perf report: Make max_stack value allow for synthesized callchains Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 27/39] perf hists: Allow for max_stack greater than PERF_MAX_STACK_DEPTH Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 34/39] perf inject: Add --strip option to strip out non-synthesized events Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 29/39] perf scripting python: Allow for max_stack greater than PERF_MAX_STACK_DEPTH Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 01/39] perf top: Filter symbols based on __map__is_kernel(map) Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 03/39] perf tools: Use __map__is_kernel() when synthesizing kernel module mmap records Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 13/39] perf report: Fix sample type validation for synthesized callchains Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 32/39] perf evlist: Add perf_evlist__remove() Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 30/39] perf script: Make scripting_max_stack value allow for synthesized callchains Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 10/39] perf tools: Rename the 'single_dep' target to 'prepare' Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 11/39] tools build: Build fixdep helper from perf and basic libs Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 04/39] tools lib api fs: Store tracing mountpoint for better error message Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 14/39] perf intel-pt: Fix potential loop forever Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 07/39] tools build: Add fixdep dependency helper Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 35/39] perf intel-pt: Add mispred-all config option to aid use with autofdo Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:20 +0200
  [PATCH 28/39] perf script: Add a setting for maximum stack depth Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:30 +0200
  [PATCH 24/39] perf intel-pt: Move branch filter logic Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:30 +0200
  [PATCH 23/39] perf inject: Set branch stack feature flag when synthesizing branch stacks Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:30 +0200
  [PATCH 33/39] perf inject: Remove more aux-related stuff when processing instruction traces Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:30 +0200
  [PATCH 18/39] perf tools: Add more documentation to export-to-postgresql.py script Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:30 +0200
  [PATCH 17/39] perf session: Warn when AUX data has been lost Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:30 +0200
  [PATCH 16/39] perf script: Allow time to be displayed in nanoseconds Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:30 +0200
  [PATCH 25/39] perf intel-pt: Support generating branch stack Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:30 +0200
  [PATCH 21/39] perf report: Also do default setup for synthesized branch stacks Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:30 +0200
  [PATCH 22/39] perf report: Skip events with null branch stacks Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:30 +0200
  [PATCH 05/39] tools build: Add Makefile.include Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-09-28 23:30 +0200
  Re: [GIT PULL 00/39] perf/core improvements and fixes Ingo Molnar <mingo@kernel.org> - 2015-09-29 09:50 +0200

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