git: ae4a8e52072a - main - bitset: implement BIT_TEST_CLR_ATOMIC & BIT_TEST_SET_ATOMIC

[Ryan Libby]

The branch main has been updated by rlibby:

URL: https://cgit.FreeBSD.org/src/commit/?id=ae4a8e52072a87bfd49d553b9b14450c626269f8

commit ae4a8e52072a87bfd49d553b9b14450c626269f8
Author:     Ryan Libby <rlibby at FreeBSD.org>
AuthorDate: 2020-12-31 21:02:45 +0000
Commit:     Ryan Libby <rlibby at FreeBSD.org>
CommitDate: 2020-12-31 21:02:45 +0000

    bitset: implement BIT_TEST_CLR_ATOMIC & BIT_TEST_SET_ATOMIC
    
    That is, provide wrappers around the atomic_testandclear and
    atomic_testandset primitives.
    
    Submitted by:   jeff
    Reviewed by:    cem, kib, markj
    Sponsored by:   Dell EMC Isilon
    Differential Revision:  https://reviews.freebsd.org/D22702
---
 share/man/man9/bitset.9 | 14 +++++++++++++-
 sys/sys/bitset.h        | 14 ++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/share/man/man9/bitset.9 b/share/man/man9/bitset.9
index d597282fea9a..1e080f515788 100644
--- a/share/man/man9/bitset.9
+++ b/share/man/man9/bitset.9
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 25, 2020
+.Dd December 31, 2020
 .Dt BITSET 9
 .Os
 .Sh NAME
@@ -60,6 +60,8 @@
 .Nm BIT_CLR_ATOMIC ,
 .Nm BIT_SET_ATOMIC ,
 .Nm BIT_SET_ATOMIC_ACQ ,
+.Nm BIT_TEST_SET_ATOMIC ,
+.Nm BIT_TEST_CLR_ATOMIC ,
 .Nm BIT_AND_ATOMIC ,
 .Nm BIT_OR_ATOMIC ,
 .Nm BIT_COPY_STORE_REL
@@ -137,6 +139,10 @@
 .Fn BIT_CLR_ATOMIC "const SETSIZE" "size_t bit" "struct STRUCTNAME *bitset"
 .Fn BIT_SET_ATOMIC "const SETSIZE" "size_t bit" "struct STRUCTNAME *bitset"
 .Fn BIT_SET_ATOMIC_ACQ "const SETSIZE" "size_t bit" "struct STRUCTNAME *bitset"
+.Ft bool
+.Fn BIT_TEST_SET_ATOMIC "const SETSIZE" "size_t bit" "struct STRUCTNAME *bitset"
+.Ft bool
+.Fn BIT_TEST_CLR_ATOMIC "const SETSIZE" "size_t bit" "struct STRUCTNAME *bitset"
 .\"
 .Fo BIT_AND_ATOMIC
 .Fa "const SETSIZE" "struct STRUCTNAME *dst" "struct STRUCTNAME *src"
@@ -205,6 +211,9 @@ in the bitset pointed to by
 The
 .Fn BIT_CLR_ATOMIC
 macro is identical, but the bit is cleared atomically.
+The
+.Fn BIT_TEST_CLR_ATOMIC
+macro atomically clears the bit and returns whether it was set.
 .Pp
 The
 .Fn BIT_COPY
@@ -236,6 +245,9 @@ macro is identical, but the bit is set atomically.
 The
 .Fn BIT_SET_ATOMIC_ACQ
 macro sets the bit with acquire semantics.
+The
+.Fn BIT_TEST_SET_ATOMIC
+macro atomically sets the bit and returns whether it was set.
 .Pp
 The
 .Fn BIT_ZERO
diff --git a/sys/sys/bitset.h b/sys/sys/bitset.h
index 97f18def7236..2b5df78a8193 100644
--- a/sys/sys/bitset.h
+++ b/sys/sys/bitset.h
@@ -173,6 +173,12 @@
 		(d)->__bits[__i] = (s1)->__bits[__i] ^ (s2)->__bits[__i];\
 } while (0)
 
+/*
+ * Note, the atomic(9) API is not consistent between clear/set and
+ * testandclear/testandset in whether the value argument is a mask
+ * or a bit index.
+ */
+
 #define	BIT_CLR_ATOMIC(_s, n, p)					\
 	atomic_clear_long(&(p)->__bits[__bitset_word(_s, n)],		\
 	    __bitset_mask((_s), n))
@@ -185,6 +191,14 @@
 	atomic_set_acq_long(&(p)->__bits[__bitset_word(_s, n)],		\
 	    __bitset_mask((_s), n))
 
+#define	BIT_TEST_CLR_ATOMIC(_s, n, p)					\
+	(atomic_testandclear_long(					\
+	    &(p)->__bits[__bitset_word((_s), (n))], (n)) != 0)
+
+#define	BIT_TEST_SET_ATOMIC(_s, n, p)					\
+	(atomic_testandset_long(					\
+	    &(p)->__bits[__bitset_word((_s), (n))], (n)) != 0)
+
 /* Convenience functions catering special cases. */
 #define	BIT_AND_ATOMIC(_s, d, s) do {					\
 	__size_t __i;							\