linux-kernel - [tip: sched/core] sched/fair: Better document newidle

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 11 Nov 2019 09:32:36 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>, bsegall@...gle.com,
        dietmar.eggemann@....com, juri.lelli@...hat.com,
        ktkhai@...tuozzo.com, mgorman@...e.de, qais.yousef@....com,
        qperret@...gle.com, rostedt@...dmis.org,
        valentin.schneider@....com, vincent.guittot@...aro.org,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched/fair: Better document newidle_balance()

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     7277a34c6be0b2972bdd1fea88c7cef409bed5b4
Gitweb:        https://git.kernel.org/tip/7277a34c6be0b2972bdd1fea88c7cef409bed5b4
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Fri, 08 Nov 2019 14:15:55 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Mon, 11 Nov 2019 08:35:18 +01:00

sched/fair: Better document newidle_balance()

Whilst chasing the pick_next_task() race, there was some confusion
about the newidle_balance() return values. Document them.

[ mingo: Minor edits. ]

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: bsegall@...gle.com
Cc: dietmar.eggemann@....com
Cc: juri.lelli@...hat.com
Cc: ktkhai@...tuozzo.com
Cc: mgorman@...e.de
Cc: qais.yousef@....com
Cc: qperret@...gle.com
Cc: rostedt@...dmis.org
Cc: valentin.schneider@....com
Cc: vincent.guittot@...aro.org
Link: https://lkml.kernel.org/r/20191108131909.488364308@infradead.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/fair.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6e622f4..c48a695 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9941,6 +9941,11 @@ static inline void nohz_newidle_balance(struct rq *this_rq) { }
 /*
  * idle_balance is called by schedule() if this_cpu is about to become
  * idle. Attempts to pull tasks from other CPUs.
+ *
+ * Returns:
+ *   < 0 - we released the lock and there are !fair tasks present
+ *     0 - failed, no new tasks
+ *   > 0 - success, new (fair) tasks present
  */
 int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
 {