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
next 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
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