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Code Issues Releases Activity

seqc: add symbolic name for in-modify bit

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Reviewed by:	mckusick
Discussed with:	markj
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Differential revision:	https://reviews.freebsd.org/D30041
This commit is contained in:
Konstantin Belousov 2021-04-30 01:39:23 +03:00
parent 62ea198e95
commit 71faea9307
1 changed files with 8 additions and 6 deletions
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14
sys/sys/seqc.h
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@ -45,13 +45,15 @@
#include <machine/cpu.h>
#define SEQC_MOD 1
/*
* Predicts from inline functions are not honored by clang.
*/
#define seqc_in_modify(seqc) ({ \
seqc_t __seqc = (seqc); \
\
__predict_false(__seqc & 1); \
__predict_false(__seqc & SEQC_MOD); \
})
static __inline void
@ -60,7 +62,7 @@ seqc_write_begin(seqc_t *seqcp)
critical_enter();
MPASS(!seqc_in_modify(*seqcp));
*seqcp += 1;
*seqcp += SEQC_MOD;
atomic_thread_fence_rel();
}
@ -69,7 +71,7 @@ seqc_write_end(seqc_t *seqcp)
{
atomic_thread_fence_rel();
*seqcp += 1;
*seqcp += SEQC_MOD;
MPASS(!seqc_in_modify(*seqcp));
critical_exit();
}
@ -85,7 +87,7 @@ static __inline seqc_t
seqc_read_notmodify(const seqc_t *seqcp)
{
return (atomic_load_acq_int(__DECONST(seqc_t *, seqcp)) & ~1);
return (atomic_load_acq_int(__DECONST(seqc_t *, seqcp)) & ~SEQC_MOD);
}
static __inline seqc_t
@ -126,7 +128,7 @@ seqc_sleepable_write_begin(seqc_t *seqcp)
{
MPASS(!seqc_in_modify(*seqcp));
*seqcp += 1;
*seqcp += SEQC_MOD;
atomic_thread_fence_rel();
}
@ -135,7 +137,7 @@ seqc_sleepable_write_end(seqc_t *seqcp)
{
atomic_thread_fence_rel();
*seqcp += 1;
*seqcp += SEQC_MOD;
MPASS(!seqc_in_modify(*seqcp));
}