linux-kernel - [tip:perf/core] perf utils: Readlink /proc/self/exe to find the perf binary

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Message-ID: <tip-55f77128e7652e537d6c226d5b56821cdb5c22de@git.kernel.org>
Date:   Mon, 27 Mar 2017 22:59:01 -0700
From:   tip-bot for Tommi Rantala <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tommi.t.rantala@...ia.com, alexander.shishkin@...ux.intel.com,
        hpa@...or.com, acme@...hat.com, mingo@...nel.org,
        peterz@...radead.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de
Subject: [tip:perf/core] perf utils: Readlink /proc/self/exe to find the
 perf binary

Commit-ID:  55f77128e7652e537d6c226d5b56821cdb5c22de
Gitweb:     http://git.kernel.org/tip/55f77128e7652e537d6c226d5b56821cdb5c22de
Author:     Tommi Rantala <tommi.t.rantala@...ia.com>
AuthorDate: Wed, 22 Mar 2017 15:06:24 +0200
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Mon, 27 Mar 2017 15:37:54 -0300

perf utils: Readlink /proc/self/exe to find the perf binary

Simplification: it is easier to open /proc/self/exe than /proc/$pid/exe.

Signed-off-by: Tommi Rantala <tommi.t.rantala@...ia.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/r/20170322130624.21881-7-tommi.t.rantala@nokia.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/header.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index cf22962..ef09f26 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -370,15 +370,11 @@ static int write_cmdline(int fd, struct perf_header *h __maybe_unused,
 			 struct perf_evlist *evlist __maybe_unused)
 {
 	char buf[MAXPATHLEN];
-	char proc[32];
 	u32 n;
 	int i, ret;
 
-	/*
-	 * actual atual path to perf binary
-	 */
-	sprintf(proc, "/proc/%d/exe", getpid());
-	ret = readlink(proc, buf, sizeof(buf) - 1);
+	/* actual path to perf binary */
+	ret = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
 	if (ret <= 0)
 		return -1;