Messages in this thread Patch in this message | | | Date | Tue, 14 Nov 2017 12:41:35 -0800 | From | Matthew Wilcox <> | Subject | New sparse warnings from sched.h |
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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
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