linux-kernel - [PATCH] perf tools: Fix permission checks

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Date:	Sun,  8 Nov 2009 18:01:06 +0200
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	mingo@...e.hu
Cc:	linux-kernel@...r.kernel.org,
	Pekka Enberg <penberg@...helsinki.fi>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: [PATCH] perf tools: Fix permission checks

The perf_event_open() system call returns EACCES if the user is not root which
results in a very confusing error message:

  $ perf record -A -a -f

    Error: perfcounter syscall returned with -1 (Permission denied)

    Fatal: No CONFIG_PERF_EVENTS=y kernel support configured?

It turns out that's because perf tools are checking only for EPERM. Fix that up
to get a much better error message:

  $ perf record -A -a -f
    Fatal: Permission error - are you root?

Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Signed-off-by: Pekka Enberg <penberg@...helsinki.fi>
---
 tools/perf/builtin-record.c |    2 +-
 tools/perf/builtin-top.c    |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 3eeef33..a4be453 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -426,7 +426,7 @@ try_again:
 	if (fd[nr_cpu][counter] < 0) {
 		int err = errno;
 
-		if (err == EPERM)
+		if (err == EPERM || err == EACCES)
 			die("Permission error - are you root?\n");
 		else if (err ==  ENODEV && profile_cpu != -1)
 			die("No such device - did you specify an out-of-range profile CPU?\n");
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index a1b1d10..e23bc74 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1027,7 +1027,7 @@ try_again:
 	if (fd[i][counter] < 0) {
 		int err = errno;
 
-		if (err == EPERM)
+		if (err == EPERM || err == EACCES)
 			die("No permission - are you root?\n");
 		/*
 		 * If it's cycles then fall back to hrtimer
-- 
1.6.3.3

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