linux-kernel - [tip:sched/core] sched/cputime: Refactor the cputime

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Message-ID: <tip-72298e5c92c50edd8cb7cfda4519483ce65fa166@git.kernel.org>
Date:   Fri, 30 Jun 2017 06:10:35 -0700
From:   "tip-bot for Gustavo A. R. Silva" <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, wanpeng.li@...mail.com,
        tglx@...utronix.de, peterz@...radead.org, sgruszka@...hat.com,
        garsilva@...eddedor.com, hpa@...or.com, fransklaver@...il.com,
        mingo@...nel.org, torvalds@...ux-foundation.org, riel@...hat.com,
        fweisbec@...il.com
Subject: [tip:sched/core] sched/cputime: Refactor the cputime_adjust() code

Commit-ID:  72298e5c92c50edd8cb7cfda4519483ce65fa166
Gitweb:     http://git.kernel.org/tip/72298e5c92c50edd8cb7cfda4519483ce65fa166
Author:     Gustavo A. R. Silva <garsilva@...eddedor.com>
AuthorDate: Thu, 29 Jun 2017 13:41:28 -0500
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 30 Jun 2017 09:37:59 +0200

sched/cputime: Refactor the cputime_adjust() code

Address a Coverity false positive, which is caused by overly
convoluted code:

Value assigned to variable 'utime' at line 619:utime = rtime;
is overwritten at line 642:utime = rtime - stime; before it
can be used. This makes such variable assignment useless.

Remove this variable assignment and refactor the code related.

Addresses-Coverity-ID: 1371643
Signed-off-by: Gustavo A. R. Silva <garsilva@...eddedor.com>
Cc: Frans Klaver <fransklaver@...il.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Stanislaw Gruszka <sgruszka@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Wanpeng Li <wanpeng.li@...mail.com>
Link: http://lkml.kernel.org/r/20170629184128.GA5271@embeddedgus
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/cputime.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index aea3135..67c70e2 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -615,19 +615,13 @@ static void cputime_adjust(struct task_cputime *curr,
 	 * userspace. Once a task gets some ticks, the monotonicy code at
 	 * 'update' will ensure things converge to the observed ratio.
 	 */
-	if (stime == 0) {
-		utime = rtime;
-		goto update;
+	if (stime != 0) {
+		if (utime == 0)
+			stime = rtime;
+		else
+			stime = scale_stime(stime, rtime, stime + utime);
 	}
 
-	if (utime == 0) {
-		stime = rtime;
-		goto update;
-	}
-
-	stime = scale_stime(stime, rtime, stime + utime);
-
-update:
 	/*
 	 * Make sure stime doesn't go backwards; this preserves monotonicity
 	 * for utime because rtime is monotonic.