linux-kernel - [tip: locking/core] seqlock: Use unique prefix for seqcount

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Date:   Thu, 10 Sep 2020 15:08:25 -0000
From:   "tip-bot2 for Ahmed S. Darwish" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Ahmed S. Darwish" <a.darwish@...utronix.de>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [tip: locking/core] seqlock: Use unique prefix for seqcount_t
 property accessors

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     5cdd25572a29e46f932d3e6eedbd07429de66431
Gitweb:        https://git.kernel.org/tip/5cdd25572a29e46f932d3e6eedbd07429de66431
Author:        Ahmed S. Darwish <a.darwish@...utronix.de>
AuthorDate:    Fri, 04 Sep 2020 17:32:28 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 10 Sep 2020 11:19:30 +02:00

seqlock: Use unique prefix for seqcount_t property accessors

At seqlock.h, the following set of functions:

    - __seqcount_ptr()
    - __seqcount_preemptible()
    - __seqcount_assert()

act as plain seqcount_t "property" accessors. Meanwhile, the following
group:

    - __seqcount_ptr()
    - __seqcount_lock_preemptible()
    - __seqcount_assert_lock_held()

act as the equivalent set, but in the generic form, taking either
seqcount_t or any of the seqcount_LOCKNAME_t variants.

This is quite confusing, especially the first member where it is called
exactly the same in both groups.

Differentiate the first group by using "__seqprop" as prefix, and also
use that same prefix for all of seqcount_LOCKNAME_t property accessors.

While at it, constify the property accessors first parameter when
appropriate.

References: 55f3560df975 ("seqlock: Extend seqcount API with associated locks")
Signed-off-by: Ahmed S. Darwish <a.darwish@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20200904153231.11994-3-a.darwish@linutronix.de
---
 include/linux/seqlock.h | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index 820ace2..0b4a22f 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -157,7 +157,9 @@ static inline void seqcount_lockdep_reader_access(const seqcount_t *s)
  */
 
 /*
- * SEQCOUNT_LOCKNAME() - Instantiate seqcount_LOCKNAME_t and helpers
+ * SEQCOUNT_LOCKNAME()	- Instantiate seqcount_LOCKNAME_t and helpers
+ * seqprop_LOCKNAME_*()	- Property accessors for seqcount_LOCKNAME_t
+ *
  * @lockname:		"LOCKNAME" part of seqcount_LOCKNAME_t
  * @locktype:		LOCKNAME canonical C data type
  * @preemptible:	preemptibility of above lockname
@@ -177,19 +179,19 @@ seqcount_##lockname##_init(seqcount_##lockname##_t *s, locktype *lock)	\
 }									\
 									\
 static __always_inline seqcount_t *					\
-__seqcount_##lockname##_ptr(seqcount_##lockname##_t *s)			\
+__seqprop_##lockname##_ptr(seqcount_##lockname##_t *s)			\
 {									\
 	return &s->seqcount;						\
 }									\
 									\
 static __always_inline bool						\
-__seqcount_##lockname##_preemptible(seqcount_##lockname##_t *s)		\
+__seqprop_##lockname##_preemptible(const seqcount_##lockname##_t *s)	\
 {									\
 	return preemptible;						\
 }									\
 									\
 static __always_inline void						\
-__seqcount_##lockname##_assert(seqcount_##lockname##_t *s)		\
+__seqprop_##lockname##_assert(const seqcount_##lockname##_t *s)		\
 {									\
 	__SEQ_LOCK(lockdep_assert_held(lockmember));			\
 }
@@ -198,17 +200,17 @@ __seqcount_##lockname##_assert(seqcount_##lockname##_t *s)		\
  * __seqprop() for seqcount_t
  */
 
-static inline seqcount_t *__seqcount_ptr(seqcount_t *s)
+static inline seqcount_t *__seqprop_ptr(seqcount_t *s)
 {
 	return s;
 }
 
-static inline bool __seqcount_preemptible(seqcount_t *s)
+static inline bool __seqprop_preemptible(const seqcount_t *s)
 {
 	return false;
 }
 
-static inline void __seqcount_assert(seqcount_t *s)
+static inline void __seqprop_assert(const seqcount_t *s)
 {
 	lockdep_assert_preemption_disabled();
 }
@@ -237,10 +239,10 @@ SEQCOUNT_LOCKNAME(ww_mutex,	struct ww_mutex,	true,	&s->lock->base)
 #define SEQCNT_WW_MUTEX_ZERO(name, lock) 	SEQCOUNT_LOCKNAME_ZERO(name, lock)
 
 #define __seqprop_case(s, lockname, prop)				\
-	seqcount_##lockname##_t: __seqcount_##lockname##_##prop((void *)(s))
+	seqcount_##lockname##_t: __seqprop_##lockname##_##prop((void *)(s))
 
 #define __seqprop(s, prop) _Generic(*(s),				\
-	seqcount_t:		__seqcount_##prop((void *)(s)),		\
+	seqcount_t:		__seqprop_##prop((void *)(s)),		\
 	__seqprop_case((s),	raw_spinlock,	prop),			\
 	__seqprop_case((s),	spinlock,	prop),			\
 	__seqprop_case((s),	rwlock,		prop),			\