mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Matthew Wilcox <willy@infradead.org>
To: luca abeni <luca.abeni@santannapisa.it>,
	Peter Zijlstra <peterz@infradead.org>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org
Subject: New sparse warnings from sched.h
Date: Tue, 14 Nov 2017 12:41:35 -0800	[thread overview]
Message-ID: <20171114204135.GA23685@bombadil.infradead.org> (raw)


commit 799ba82de01e7543f6b2042e1a739f3a20255f23
Author: luca abeni <luca.abeni@santannapisa.it>
Date:   Thu Sep 7 12:09:31 2017 +0200

    sched/deadline: Use C bitfields for the state flags
    
    Ask the compiler to use a single bit for storing true / false values,
    instead of wasting the size of a whole int value.
    Tested with gcc 5.4.0 on x86_64, and the compiler produces the expected
    Assembly (similar to the Assembly code generated when explicitly accessing
    the bits with bitmasks, "&" and "|").

produces four warnings from sparse for every file which includes sched.h:

./include/linux/sched.h:476:62: error: dubious one-bit signed bitfield
./include/linux/sched.h:477:62: error: dubious one-bit signed bitfield
./include/linux/sched.h:478:62: error: dubious one-bit signed bitfield
./include/linux/sched.h:479:62: error: dubious one-bit signed bitfield

This seems like the trivial fix (untested):


diff --git a/include/linux/sched.h b/include/linux/sched.h
index a5dc7c98b0a2..21991d668d35 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

             reply	other threads:[~2017-11-14 20:41 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-14 20:41 Matthew Wilcox [this message]
2017-11-15  8:27 ` Ingo Molnar
2017-11-15 14:54   ` Matthew Wilcox
2017-11-15 15:10     ` Ingo Molnar
2017-11-15  8:36 ` luca abeni

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20171114204135.GA23685@bombadil.infradead.org \
    --to=willy@infradead.org \
    --cc=bristot@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luca.abeni@santannapisa.it \
    --cc=mingo@kernel.org \
    --cc=peterz@infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox

all inboxes | Powered by JetHome®