[PATCH 1/5] seqlock: simplify SEQCOUNT_LOCKNAME()

Oleg Nesterov
2023-09-13T15:51:38Z

1. Kill the "lockmember" argument. It is always s->lock plus
__seqprop_##lockname##_sequence() already uses s->lock and
ignores "lockmember".

2. Kill the "lock_acquire" argument. __seqprop_##lockname##_sequence()
can use the same "lockbase" prefix for _lock and _unlock.

Apart from line numbers, gcc -E outputs the same code.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
include/linux/seqlock.h | 18 ++++++++----------
1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index 987a59d977c5..ac6631bd5706 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -191,11 +191,9 @@ static inline void seqcount_lockdep_reader_access(const seqcount_t *s)
* @lockname: "LOCKNAME" part of seqcount_LOCKNAME_t
* @locktype: LOCKNAME canonical C data type
* @preemptible: preemptibility of above locktype
- * @lockmember: argument for lockdep_assert_held()
- * @lockbase: associated lock release function (prefix only)
- * @lock_acquire: associated lock acquisition function (full call)
+ * @lockbase: prefix for associated lock/unlock
*/
-#define SEQCOUNT_LOCKNAME(lockname, locktype, preemptible, lockmember, lockbase, lock_acquire) \
+#define SEQCOUNT_LOCKNAME(lockname, locktype, preemptible, lockbase) \
typedef struct seqcount_##lockname { \
seqcount_t seqcount; \
__SEQ_LOCK(locktype *lock); \
@@ -216,7 +214,7 @@ __seqprop_##lockname##_sequence(const seqcount_##lockname##_t *s) \
return seq; \
\
if (preemptible && unlikely(seq & 1)) { \
- __SEQ_LOCK(lock_acquire); \
+ __SEQ_LOCK(lockbase##_lock(s->lock)); \
__SEQ_LOCK(lockbase##_unlock(s->lock)); \
\
/* \
@@ -242,7 +240,7 @@ __seqprop_##lockname##_preemptible(const seqcount_##lockname##_t *s) \
static __always_inline void \
__seqprop_##lockname##_assert(const seqcount_##lockname##_t *s) \
{ \
- __SEQ_LOCK(lockdep_assert_held(lockmember)); \
+ __SEQ_LOCK(lockdep_assert_held(s->lock)); \
}

/*
@@ -271,10 +269,10 @@ static inline void __seqprop_assert(const seqcount_t *s)

#define __SEQ_RT IS_ENABLED(CONFIG_PREEMPT_RT)

-SEQCOUNT_LOCKNAME(raw_spinlock, raw_spinlock_t, false, s->lock, raw_spin, raw_spin_lock(s->lock))
-SEQCOUNT_LOCKNAME(spinlock, spinlock_t, __SEQ_RT, s->lock, spin, spin_lock(s->lock))
-SEQCOUNT_LOCKNAME(rwlock, rwlock_t, __SEQ_RT, s->lock, read, read_lock(s->lock))
-SEQCOUNT_LOCKNAME(mutex, struct mutex, true, s->lock, mutex, mutex_lock(s->lock))
+SEQCOUNT_LOCKNAME(raw_spinlock, raw_spinlock_t, false, raw_spin)
+SEQCOUNT_LOCKNAME(spinlock, spinlock_t, __SEQ_RT, spin)
+SEQCOUNT_LOCKNAME(rwlock, rwlock_t, __SEQ_RT, read)
+SEQCOUNT_LOCKNAME(mutex, struct mutex, true, mutex)

/*
* SEQCNT_LOCKNAME_ZERO - static initializer for seqcount_LOCKNAME_t
--
2.25.1.362.g51ebf55