linux-kernel - [tip:sched/urgent] sched/deadline: Don't use dubious signed bitfields

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Date:   Tue, 21 Nov 2017 00:30:48 -0800
From:   tip-bot for Dan Carpenter <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tglx@...utronix.de, peterz@...radead.org, mingo@...nel.org,
        linux-kernel@...r.kernel.org, lucien.xin@...il.com,
        luca.abeni@...tannapisa.it, dan.carpenter@...cle.com,
        willy@...radead.org, hpa@...or.com, torvalds@...ux-foundation.org
Subject: [tip:sched/urgent] sched/deadline: Don't use dubious signed
 bitfields

Commit-ID:  aa5222e92f8000ed3c1c38dddf11c83222aadfb3
Gitweb:     https://git.kernel.org/tip/aa5222e92f8000ed3c1c38dddf11c83222aadfb3
Author:     Dan Carpenter <dan.carpenter@...cle.com>
AuthorDate: Fri, 13 Oct 2017 10:01:22 +0300
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 21 Nov 2017 09:25:01 +0100

sched/deadline: Don't use dubious signed bitfields

It doesn't cause a run-time bug, but these bitfields should be unsigned.
When it's signed ->dl_throttled is set to either 0 or -1, instead of
0 and 1 as expected.

The sched.h file is included into tons of places so Sparse generates
a flood of warnings like this:

  ./include/linux/sched.h:477:54: error: dubious one-bit signed bitfield

Reported-by: Matthew Wilcox <willy@...radead.org>
Reported-by: Xin Long <lucien.xin@...il.com>
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Reviewed-by: Luca Abeni <luca.abeni@...tannapisa.it>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: kernel-janitors@...r.kernel.org
Cc: luca abeni <luca.abeni@...tannapisa.it>
Link: http://lkml.kernel.org/r/20171013070121.dzcncojuj2f4utij@mwanda
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 include/linux/sched.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index a5dc7c9..21991d6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -473,10 +473,10 @@ struct sched_dl_entity {
 	 * conditions between the inactive timer handler and the wakeup
 	 * code.
 	 */
-	int				dl_throttled      : 1;
-	int				dl_boosted        : 1;
-	int				dl_yielded        : 1;
-	int				dl_non_contending : 1;
+	unsigned int			dl_throttled      : 1;
+	unsigned int			dl_boosted        : 1;
+	unsigned int			dl_yielded        : 1;
+	unsigned int			dl_non_contending : 1;
 
 	/*
 	 * Bandwidth enforcement timer. Each -deadline task has its