[PATCH 0/5] seqlock: Cleanups

[PATCH 0/5] seqlock: Cleanups

[Peter Zijlstra]

Hi,

These are some minor cleanups that go on top of darwi's seqlock patches:

  https://lkml.kernel.org/r/20200720155530.1173732-1-a.darwish@linutronix.de

It's mostly trimming excessive manual repetition and a few naming niggles.

The series has been exposed to 0-day for a while now, so I'm going to push the
lot out to tip/locking/core.

[ 0day found a Sparse bug in it's _Generic() implementation that has since been
  fixed by Luc ]

---
 seqlock.h |  292 +++++++++++++++++---------------------------------------------
 1 file changed, 84 insertions(+), 208 deletions(-)

[PATCH 1/5] seqlock: s/__SEQ_LOCKDEP/__SEQ_LOCK/g

[Peter Zijlstra]

__SEQ_LOCKDEP() is an expression gate for the
seqcount_LOCKNAME_t::lock member. Rename it to be about the member,
not the gate condition.

Later (PREEMPT_RT) patches will make the member available for !LOCKDEP
configs.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 include/linux/seqlock.h |   20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -133,20 +133,20 @@ static inline void seqcount_lockdep_read
  */
 
 #ifdef CONFIG_LOCKDEP
-#define __SEQ_LOCKDEP(expr)	expr
+#define __SEQ_LOCK(expr)	expr
 #else
-#define __SEQ_LOCKDEP(expr)
+#define __SEQ_LOCK(expr)
 #endif
 
 #define SEQCOUNT_LOCKTYPE_ZERO(seq_name, assoc_lock) {			\
 	.seqcount		= SEQCNT_ZERO(seq_name.seqcount),	\
-	__SEQ_LOCKDEP(.lock	= (assoc_lock))				\
+	__SEQ_LOCK(.lock	= (assoc_lock))				\
 }
 
 #define seqcount_locktype_init(s, assoc_lock)				\
 do {									\
 	seqcount_init(&(s)->seqcount);					\
-	__SEQ_LOCKDEP((s)->lock = (assoc_lock));			\
+	__SEQ_LOCK((s)->lock = (assoc_lock));				\
 } while (0)
 
 /**
@@ -161,7 +161,7 @@ do {									\
  */
 typedef struct seqcount_spinlock {
 	seqcount_t	seqcount;
-	__SEQ_LOCKDEP(spinlock_t	*lock);
+	__SEQ_LOCK(spinlock_t	*lock);
 } seqcount_spinlock_t;
 
 /**
@@ -192,7 +192,7 @@ typedef struct seqcount_spinlock {
  */
 typedef struct seqcount_raw_spinlock {
 	seqcount_t      seqcount;
-	__SEQ_LOCKDEP(raw_spinlock_t	*lock);
+	__SEQ_LOCK(raw_spinlock_t	*lock);
 } seqcount_raw_spinlock_t;
 
 /**
@@ -223,7 +223,7 @@ typedef struct seqcount_raw_spinlock {
  */
 typedef struct seqcount_rwlock {
 	seqcount_t      seqcount;
-	__SEQ_LOCKDEP(rwlock_t		*lock);
+	__SEQ_LOCK(rwlock_t		*lock);
 } seqcount_rwlock_t;
 
 /**
@@ -257,7 +257,7 @@ typedef struct seqcount_rwlock {
  */
 typedef struct seqcount_mutex {
 	seqcount_t      seqcount;
-	__SEQ_LOCKDEP(struct mutex	*lock);
+	__SEQ_LOCK(struct mutex	*lock);
 } seqcount_mutex_t;
 
 /**
@@ -291,7 +291,7 @@ typedef struct seqcount_mutex {
  */
 typedef struct seqcount_ww_mutex {
 	seqcount_t      seqcount;
-	__SEQ_LOCKDEP(struct ww_mutex	*lock);
+	__SEQ_LOCK(struct ww_mutex	*lock);
 } seqcount_ww_mutex_t;
 
 /**
@@ -329,7 +329,7 @@ __seqcount_##locktype##_preemptible(seqc
 static inline void							\
 __seqcount_##locktype##_assert(seqcount_##locktype##_t *s)		\
 {									\
-	__SEQ_LOCKDEP(lockdep_assert_held(lockmember));			\
+	__SEQ_LOCK(lockdep_assert_held(lockmember));			\
 }
 
 /*

[PATCH 2/5] seqlock: Fold seqcount_LOCKNAME_t definition

[Peter Zijlstra]

Manual repetition is boring and error prone.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 include/linux/seqlock.h |  140 +++++++++++++-----------------------------------
 1 file changed, 38 insertions(+), 102 deletions(-)

--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -150,21 +150,6 @@ do {									\
 } while (0)
 
 /**
- * typedef seqcount_spinlock_t - sequence counter with spinlock associated
- * @seqcount:	The real sequence counter
- * @lock:	Pointer to the associated spinlock
- *
- * A plain sequence counter with external writer synchronization by a
- * spinlock. The spinlock is associated to the sequence count in the
- * static initializer or init function. This enables lockdep to validate
- * that the write side critical section is properly serialized.
- */
-typedef struct seqcount_spinlock {
-	seqcount_t	seqcount;
-	__SEQ_LOCK(spinlock_t	*lock);
-} seqcount_spinlock_t;
-
-/**
  * SEQCNT_SPINLOCK_ZERO - static initializer for seqcount_spinlock_t
  * @name:	Name of the seqcount_spinlock_t instance
  * @lock:	Pointer to the associated spinlock
@@ -181,21 +166,6 @@ typedef struct seqcount_spinlock {
 	seqcount_locktype_init(s, lock)
 
 /**
- * typedef seqcount_raw_spinlock_t - sequence count with raw spinlock associated
- * @seqcount:	The real sequence counter
- * @lock:	Pointer to the associated raw spinlock
- *
- * A plain sequence counter with external writer synchronization by a
- * raw spinlock. The raw spinlock is associated to the sequence count in
- * the static initializer or init function. This enables lockdep to
- * validate that the write side critical section is properly serialized.
- */
-typedef struct seqcount_raw_spinlock {
-	seqcount_t      seqcount;
-	__SEQ_LOCK(raw_spinlock_t	*lock);
-} seqcount_raw_spinlock_t;
-
-/**
  * SEQCNT_RAW_SPINLOCK_ZERO - static initializer for seqcount_raw_spinlock_t
  * @name:	Name of the seqcount_raw_spinlock_t instance
  * @lock:	Pointer to the associated raw_spinlock
@@ -212,21 +182,6 @@ typedef struct seqcount_raw_spinlock {
 	seqcount_locktype_init(s, lock)
 
 /**
- * typedef seqcount_rwlock_t - sequence count with rwlock associated
- * @seqcount:	The real sequence counter
- * @lock:	Pointer to the associated rwlock
- *
- * A plain sequence counter with external writer synchronization by a
- * rwlock. The rwlock is associated to the sequence count in the static
- * initializer or init function. This enables lockdep to validate that
- * the write side critical section is properly serialized.
- */
-typedef struct seqcount_rwlock {
-	seqcount_t      seqcount;
-	__SEQ_LOCK(rwlock_t		*lock);
-} seqcount_rwlock_t;
-
-/**
  * SEQCNT_RWLOCK_ZERO - static initializer for seqcount_rwlock_t
  * @name:	Name of the seqcount_rwlock_t instance
  * @lock:	Pointer to the associated rwlock
@@ -243,24 +198,6 @@ typedef struct seqcount_rwlock {
 	seqcount_locktype_init(s, lock)
 
 /**
- * typedef seqcount_mutex_t - sequence count with mutex associated
- * @seqcount:	The real sequence counter
- * @lock:	Pointer to the associated mutex
- *
- * A plain sequence counter with external writer synchronization by a
- * mutex. The mutex is associated to the sequence counter in the static
- * initializer or init function. This enables lockdep to validate that
- * the write side critical section is properly serialized.
- *
- * The write side API functions write_seqcount_begin()/end() automatically
- * disable and enable preemption when used with seqcount_mutex_t.
- */
-typedef struct seqcount_mutex {
-	seqcount_t      seqcount;
-	__SEQ_LOCK(struct mutex	*lock);
-} seqcount_mutex_t;
-
-/**
  * SEQCNT_MUTEX_ZERO - static initializer for seqcount_mutex_t
  * @name:	Name of the seqcount_mutex_t instance
  * @lock:	Pointer to the associated mutex
@@ -277,24 +214,6 @@ typedef struct seqcount_mutex {
 	seqcount_locktype_init(s, lock)
 
 /**
- * typedef seqcount_ww_mutex_t - sequence count with ww_mutex associated
- * @seqcount:	The real sequence counter
- * @lock:	Pointer to the associated ww_mutex
- *
- * A plain sequence counter with external writer synchronization by a
- * ww_mutex. The ww_mutex is associated to the sequence counter in the static
- * initializer or init function. This enables lockdep to validate that
- * the write side critical section is properly serialized.
- *
- * The write side API functions write_seqcount_begin()/end() automatically
- * disable and enable preemption when used with seqcount_ww_mutex_t.
- */
-typedef struct seqcount_ww_mutex {
-	seqcount_t      seqcount;
-	__SEQ_LOCK(struct ww_mutex	*lock);
-} seqcount_ww_mutex_t;
-
-/**
  * SEQCNT_WW_MUTEX_ZERO - static initializer for seqcount_ww_mutex_t
  * @name:	Name of the seqcount_ww_mutex_t instance
  * @lock:	Pointer to the associated ww_mutex
@@ -310,30 +229,50 @@ typedef struct seqcount_ww_mutex {
 #define seqcount_ww_mutex_init(s, lock)					\
 	seqcount_locktype_init(s, lock)
 
-/*
- * @preempt: Is the associated write serialization lock preemtpible?
+/**
+ * typedef seqcount_LOCKNAME_t - sequence counter with spinlock associated
+ * @seqcount:	The real sequence counter
+ * @lock:	Pointer to the associated spinlock
+ *
+ * A plain sequence counter with external writer synchronization by a
+ * spinlock. The spinlock is associated to the sequence count in the
+ * static initializer or init function. This enables lockdep to validate
+ * that the write side critical section is properly serialized.
  */
-#define SEQCOUNT_LOCKTYPE(locktype, preempt, lockmember)		\
-static inline seqcount_t *						\
-__seqcount_##locktype##_ptr(seqcount_##locktype##_t *s)			\
+
+/*
+ * SEQCOUNT_LOCKTYPE() - Instantiate seqcount_LOCKNAME_t and helpers
+ * @locktype:		actual typename
+ * @lockname:		name
+ * @preemptible:	preemptibility of above locktype
+ * @lockmember:		argument for lockdep_assert_held()
+ */
+#define SEQCOUNT_LOCKTYPE(locktype, lockname, preemptible, lockmember)	\
+typedef struct seqcount_##lockname {					\
+	seqcount_t		seqcount;				\
+	__SEQ_LOCK(locktype	*lock);					\
+} seqcount_##lockname##_t;						\
+									\
+static __always_inline seqcount_t *					\
+__seqcount_##lockname##_ptr(seqcount_##lockname##_t *s)			\
 {									\
 	return &s->seqcount;						\
 }									\
 									\
-static inline bool							\
-__seqcount_##locktype##_preemptible(seqcount_##locktype##_t *s)		\
+static __always_inline bool						\
+__seqcount_##lockname##_preemptible(seqcount_##lockname##_t *s)		\
 {									\
-	return preempt;							\
+	return preemptible;						\
 }									\
 									\
-static inline void							\
-__seqcount_##locktype##_assert(seqcount_##locktype##_t *s)		\
+static __always_inline void						\
+__seqcount_##lockname##_assert(seqcount_##lockname##_t *s)		\
 {									\
 	__SEQ_LOCK(lockdep_assert_held(lockmember));			\
 }
 
 /*
- * Similar hooks, but for plain seqcount_t
+ * __seqprop() for seqcount_t
  */
 
 static inline seqcount_t *__seqcount_ptr(seqcount_t *s)
@@ -351,17 +290,14 @@ static inline void __seqcount_assert(seq
 	lockdep_assert_preemption_disabled();
 }
 
-/*
- * @s: Pointer to seqcount_locktype_t, generated hooks first parameter.
- */
-SEQCOUNT_LOCKTYPE(raw_spinlock,	false,	s->lock)
-SEQCOUNT_LOCKTYPE(spinlock,	false,	s->lock)
-SEQCOUNT_LOCKTYPE(rwlock,	false,	s->lock)
-SEQCOUNT_LOCKTYPE(mutex,	true,	s->lock)
-SEQCOUNT_LOCKTYPE(ww_mutex,	true,	&s->lock->base)
+SEQCOUNT_LOCKTYPE(raw_spinlock_t,	raw_spinlock,	false,	s->lock)
+SEQCOUNT_LOCKTYPE(spinlock_t,		spinlock,	false,	s->lock)
+SEQCOUNT_LOCKTYPE(rwlock_t,		rwlock,		false,	s->lock)
+SEQCOUNT_LOCKTYPE(struct mutex,		mutex,		true,	s->lock)
+SEQCOUNT_LOCKTYPE(struct ww_mutex,	ww_mutex,	true,	&s->lock->base)
 
-#define __seqprop_case(s, locktype, prop)				\
-	seqcount_##locktype##_t: __seqcount_##locktype##_##prop((void *)(s))
+#define __seqprop_case(s, lockname, prop)				\
+	seqcount_##lockname##_t: __seqcount_##lockname##_##prop((void *)(s))
 
 #define __seqprop(s, prop) _Generic(*(s),				\
 	seqcount_t:		__seqcount_##prop((void *)(s)),		\

[PATCH 3/5] seqlock: Fold seqcount_LOCKNAME_init() definition

[Peter Zijlstra]

Manual repetition is boring and error prone.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 include/linux/seqlock.h |   61 +++++++++++-------------------------------------
 1 file changed, 14 insertions(+), 47 deletions(-)

--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -143,12 +143,6 @@ static inline void seqcount_lockdep_read
 	__SEQ_LOCK(.lock	= (assoc_lock))				\
 }
 
-#define seqcount_locktype_init(s, assoc_lock)				\
-do {									\
-	seqcount_init(&(s)->seqcount);					\
-	__SEQ_LOCK((s)->lock = (assoc_lock));				\
-} while (0)
-
 /**
  * SEQCNT_SPINLOCK_ZERO - static initializer for seqcount_spinlock_t
  * @name:	Name of the seqcount_spinlock_t instance
@@ -158,14 +152,6 @@ do {									\
 	SEQCOUNT_LOCKTYPE_ZERO(name, lock)
 
 /**
- * seqcount_spinlock_init - runtime initializer for seqcount_spinlock_t
- * @s:		Pointer to the seqcount_spinlock_t instance
- * @lock:	Pointer to the associated spinlock
- */
-#define seqcount_spinlock_init(s, lock)					\
-	seqcount_locktype_init(s, lock)
-
-/**
  * SEQCNT_RAW_SPINLOCK_ZERO - static initializer for seqcount_raw_spinlock_t
  * @name:	Name of the seqcount_raw_spinlock_t instance
  * @lock:	Pointer to the associated raw_spinlock
@@ -174,14 +160,6 @@ do {									\
 	SEQCOUNT_LOCKTYPE_ZERO(name, lock)
 
 /**
- * seqcount_raw_spinlock_init - runtime initializer for seqcount_raw_spinlock_t
- * @s:		Pointer to the seqcount_raw_spinlock_t instance
- * @lock:	Pointer to the associated raw_spinlock
- */
-#define seqcount_raw_spinlock_init(s, lock)				\
-	seqcount_locktype_init(s, lock)
-
-/**
  * SEQCNT_RWLOCK_ZERO - static initializer for seqcount_rwlock_t
  * @name:	Name of the seqcount_rwlock_t instance
  * @lock:	Pointer to the associated rwlock
@@ -190,14 +168,6 @@ do {									\
 	SEQCOUNT_LOCKTYPE_ZERO(name, lock)
 
 /**
- * seqcount_rwlock_init - runtime initializer for seqcount_rwlock_t
- * @s:		Pointer to the seqcount_rwlock_t instance
- * @lock:	Pointer to the associated rwlock
- */
-#define seqcount_rwlock_init(s, lock)					\
-	seqcount_locktype_init(s, lock)
-
-/**
  * SEQCNT_MUTEX_ZERO - static initializer for seqcount_mutex_t
  * @name:	Name of the seqcount_mutex_t instance
  * @lock:	Pointer to the associated mutex
@@ -206,14 +176,6 @@ do {									\
 	SEQCOUNT_LOCKTYPE_ZERO(name, lock)
 
 /**
- * seqcount_mutex_init - runtime initializer for seqcount_mutex_t
- * @s:		Pointer to the seqcount_mutex_t instance
- * @lock:	Pointer to the associated mutex
- */
-#define seqcount_mutex_init(s, lock)					\
-	seqcount_locktype_init(s, lock)
-
-/**
  * SEQCNT_WW_MUTEX_ZERO - static initializer for seqcount_ww_mutex_t
  * @name:	Name of the seqcount_ww_mutex_t instance
  * @lock:	Pointer to the associated ww_mutex
@@ -222,15 +184,7 @@ do {									\
 	SEQCOUNT_LOCKTYPE_ZERO(name, lock)
 
 /**
- * seqcount_ww_mutex_init - runtime initializer for seqcount_ww_mutex_t
- * @s:		Pointer to the seqcount_ww_mutex_t instance
- * @lock:	Pointer to the associated ww_mutex
- */
-#define seqcount_ww_mutex_init(s, lock)					\
-	seqcount_locktype_init(s, lock)
-
-/**
- * typedef seqcount_LOCKNAME_t - sequence counter with spinlock associated
+ * typedef seqcount_LOCKNAME_t - sequence counter with LOCKTYPR associated
  * @seqcount:	The real sequence counter
  * @lock:	Pointer to the associated spinlock
  *
@@ -240,6 +194,12 @@ do {									\
  * that the write side critical section is properly serialized.
  */
 
+/**
+ * seqcount_LOCKNAME_init() - runtime initializer for seqcount_LOCKNAME_t
+ * @s:		Pointer to the seqcount_LOCKNAME_t instance
+ * @lock:	Pointer to the associated LOCKTYPE
+ */
+
 /*
  * SEQCOUNT_LOCKTYPE() - Instantiate seqcount_LOCKNAME_t and helpers
  * @locktype:		actual typename
@@ -253,6 +213,13 @@ typedef struct seqcount_##lockname {
 	__SEQ_LOCK(locktype	*lock);					\
 } seqcount_##lockname##_t;						\
 									\
+static __always_inline void						\
+seqcount_##lockname##_init(seqcount_##lockname##_t *s, locktype *lock)	\
+{									\
+	seqcount_init(&s->seqcount);					\
+	__SEQ_LOCK(s->lock = lock);					\
+}									\
+									\
 static __always_inline seqcount_t *					\
 __seqcount_##lockname##_ptr(seqcount_##lockname##_t *s)			\
 {									\

[PATCH 4/5] seqcount: Compress SEQCNT_LOCKNAME_ZERO()

[Peter Zijlstra]

Less is more.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 include/linux/seqlock.h |   63 +++++++++++++-----------------------------------
 1 file changed, 18 insertions(+), 45 deletions(-)

--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -138,51 +138,6 @@ static inline void seqcount_lockdep_read
 #define __SEQ_LOCK(expr)
 #endif
 
-#define SEQCOUNT_LOCKTYPE_ZERO(seq_name, assoc_lock) {			\
-	.seqcount		= SEQCNT_ZERO(seq_name.seqcount),	\
-	__SEQ_LOCK(.lock	= (assoc_lock))				\
-}
-
-/**
- * SEQCNT_SPINLOCK_ZERO - static initializer for seqcount_spinlock_t
- * @name:	Name of the seqcount_spinlock_t instance
- * @lock:	Pointer to the associated spinlock
- */
-#define SEQCNT_SPINLOCK_ZERO(name, lock)				\
-	SEQCOUNT_LOCKTYPE_ZERO(name, lock)
-
-/**
- * SEQCNT_RAW_SPINLOCK_ZERO - static initializer for seqcount_raw_spinlock_t
- * @name:	Name of the seqcount_raw_spinlock_t instance
- * @lock:	Pointer to the associated raw_spinlock
- */
-#define SEQCNT_RAW_SPINLOCK_ZERO(name, lock)				\
-	SEQCOUNT_LOCKTYPE_ZERO(name, lock)
-
-/**
- * SEQCNT_RWLOCK_ZERO - static initializer for seqcount_rwlock_t
- * @name:	Name of the seqcount_rwlock_t instance
- * @lock:	Pointer to the associated rwlock
- */
-#define SEQCNT_RWLOCK_ZERO(name, lock)					\
-	SEQCOUNT_LOCKTYPE_ZERO(name, lock)
-
-/**
- * SEQCNT_MUTEX_ZERO - static initializer for seqcount_mutex_t
- * @name:	Name of the seqcount_mutex_t instance
- * @lock:	Pointer to the associated mutex
- */
-#define SEQCNT_MUTEX_ZERO(name, lock)					\
-	SEQCOUNT_LOCKTYPE_ZERO(name, lock)
-
-/**
- * SEQCNT_WW_MUTEX_ZERO - static initializer for seqcount_ww_mutex_t
- * @name:	Name of the seqcount_ww_mutex_t instance
- * @lock:	Pointer to the associated ww_mutex
- */
-#define SEQCNT_WW_MUTEX_ZERO(name, lock)				\
-	SEQCOUNT_LOCKTYPE_ZERO(name, lock)
-
 /**
  * typedef seqcount_LOCKNAME_t - sequence counter with LOCKTYPR associated
  * @seqcount:	The real sequence counter
@@ -263,6 +218,24 @@ SEQCOUNT_LOCKTYPE(rwlock_t,		rwlock,		fa
 SEQCOUNT_LOCKTYPE(struct mutex,		mutex,		true,	s->lock)
 SEQCOUNT_LOCKTYPE(struct ww_mutex,	ww_mutex,	true,	&s->lock->base)
 
+/**
+ * SEQCNT_LOCKNAME_ZERO - static initializer for seqcount_LOCKNAME_t
+ * @name:	Name of the seqcount_LOCKNAME_t instance
+ * @lock:	Pointer to the associated LOCKTYPE
+ */
+
+#define SEQCOUNT_LOCKTYPE_ZERO(seq_name, assoc_lock) {			\
+	.seqcount		= SEQCNT_ZERO(seq_name.seqcount),	\
+	__SEQ_LOCK(.lock	= (assoc_lock))				\
+}
+
+#define SEQCNT_SPINLOCK_ZERO(name, lock)	SEQCOUNT_LOCKTYPE_ZERO(name, lock)
+#define SEQCNT_RAW_SPINLOCK_ZERO(name, lock)	SEQCOUNT_LOCKTYPE_ZERO(name, lock)
+#define SEQCNT_RWLOCK_ZERO(name, lock)		SEQCOUNT_LOCKTYPE_ZERO(name, lock)
+#define SEQCNT_MUTEX_ZERO(name, lock)		SEQCOUNT_LOCKTYPE_ZERO(name, lock)
+#define SEQCNT_WW_MUTEX_ZERO(name, lock) 	SEQCOUNT_LOCKTYPE_ZERO(name, lock)
+
+
 #define __seqprop_case(s, lockname, prop)				\
 	seqcount_##lockname##_t: __seqcount_##lockname##_##prop((void *)(s))
 

[PATCH 5/5] seqcount: More consistent seqprop names

[Peter Zijlstra]

Attempt uniformity and brevity.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 include/linux/seqlock.h |   52 ++++++++++++++++++++++++------------------------
 1 file changed, 26 insertions(+), 26 deletions(-)

--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -247,9 +247,9 @@ SEQCOUNT_LOCKTYPE(struct ww_mutex,	ww_mu
 	__seqprop_case((s),	mutex,		prop),			\
 	__seqprop_case((s),	ww_mutex,	prop))
 
-#define __to_seqcount_t(s)				__seqprop(s, ptr)
-#define __associated_lock_exists_and_is_preemptible(s)	__seqprop(s, preemptible)
-#define __assert_write_section_is_protected(s)		__seqprop(s, assert)
+#define __seqcount_ptr(s)		__seqprop(s, ptr)
+#define __seqcount_lock_preemptible(s)	__seqprop(s, preemptible)
+#define __seqcount_assert_lock_held(s)	__seqprop(s, assert)
 
 /**
  * __read_seqcount_begin() - begin a seqcount_t read section w/o barrier
@@ -266,7 +266,7 @@ SEQCOUNT_LOCKTYPE(struct ww_mutex,	ww_mu
  * Return: count to be passed to read_seqcount_retry()
  */
 #define __read_seqcount_begin(s)					\
-	__read_seqcount_t_begin(__to_seqcount_t(s))
+	__read_seqcount_t_begin(__seqcount_ptr(s))
 
 static inline unsigned __read_seqcount_t_begin(const seqcount_t *s)
 {
@@ -289,7 +289,7 @@ static inline unsigned __read_seqcount_t
  * Return: count to be passed to read_seqcount_retry()
  */
 #define raw_read_seqcount_begin(s)					\
-	raw_read_seqcount_t_begin(__to_seqcount_t(s))
+	raw_read_seqcount_t_begin(__seqcount_ptr(s))
 
 static inline unsigned raw_read_seqcount_t_begin(const seqcount_t *s)
 {
@@ -305,7 +305,7 @@ static inline unsigned raw_read_seqcount
  * Return: count to be passed to read_seqcount_retry()
  */
 #define read_seqcount_begin(s)						\
-	read_seqcount_t_begin(__to_seqcount_t(s))
+	read_seqcount_t_begin(__seqcount_ptr(s))
 
 static inline unsigned read_seqcount_t_begin(const seqcount_t *s)
 {
@@ -325,7 +325,7 @@ static inline unsigned read_seqcount_t_b
  * Return: count to be passed to read_seqcount_retry()
  */
 #define raw_read_seqcount(s)						\
-	raw_read_seqcount_t(__to_seqcount_t(s))
+	raw_read_seqcount_t(__seqcount_ptr(s))
 
 static inline unsigned raw_read_seqcount_t(const seqcount_t *s)
 {
@@ -353,7 +353,7 @@ static inline unsigned raw_read_seqcount
  * Return: count to be passed to read_seqcount_retry()
  */
 #define raw_seqcount_begin(s)						\
-	raw_seqcount_t_begin(__to_seqcount_t(s))
+	raw_seqcount_t_begin(__seqcount_ptr(s))
 
 static inline unsigned raw_seqcount_t_begin(const seqcount_t *s)
 {
@@ -380,7 +380,7 @@ static inline unsigned raw_seqcount_t_be
  * Return: true if a read section retry is required, else false
  */
 #define __read_seqcount_retry(s, start)					\
-	__read_seqcount_t_retry(__to_seqcount_t(s), start)
+	__read_seqcount_t_retry(__seqcount_ptr(s), start)
 
 static inline int __read_seqcount_t_retry(const seqcount_t *s, unsigned start)
 {
@@ -400,7 +400,7 @@ static inline int __read_seqcount_t_retr
  * Return: true if a read section retry is required, else false
  */
 #define read_seqcount_retry(s, start)					\
-	read_seqcount_t_retry(__to_seqcount_t(s), start)
+	read_seqcount_t_retry(__seqcount_ptr(s), start)
 
 static inline int read_seqcount_t_retry(const seqcount_t *s, unsigned start)
 {
@@ -414,10 +414,10 @@ static inline int read_seqcount_t_retry(
  */
 #define raw_write_seqcount_begin(s)					\
 do {									\
-	if (__associated_lock_exists_and_is_preemptible(s))		\
+	if (__seqcount_lock_preemptible(s))				\
 		preempt_disable();					\
 									\
-	raw_write_seqcount_t_begin(__to_seqcount_t(s));			\
+	raw_write_seqcount_t_begin(__seqcount_ptr(s));			\
 } while (0)
 
 static inline void raw_write_seqcount_t_begin(seqcount_t *s)
@@ -433,9 +433,9 @@ static inline void raw_write_seqcount_t_
  */
 #define raw_write_seqcount_end(s)					\
 do {									\
-	raw_write_seqcount_t_end(__to_seqcount_t(s));			\
+	raw_write_seqcount_t_end(__seqcount_ptr(s));			\
 									\
-	if (__associated_lock_exists_and_is_preemptible(s))		\
+	if (__seqcount_lock_preemptible(s))				\
 		preempt_enable();					\
 } while (0)
 
@@ -456,12 +456,12 @@ static inline void raw_write_seqcount_t_
  */
 #define write_seqcount_begin_nested(s, subclass)			\
 do {									\
-	__assert_write_section_is_protected(s);				\
+	__seqcount_assert_lock_held(s);					\
 									\
-	if (__associated_lock_exists_and_is_preemptible(s))		\
+	if (__seqcount_lock_preemptible(s))				\
 		preempt_disable();					\
 									\
-	write_seqcount_t_begin_nested(__to_seqcount_t(s), subclass);	\
+	write_seqcount_t_begin_nested(__seqcount_ptr(s), subclass);	\
 } while (0)
 
 static inline void write_seqcount_t_begin_nested(seqcount_t *s, int subclass)
@@ -483,12 +483,12 @@ static inline void write_seqcount_t_begi
  */
 #define write_seqcount_begin(s)						\
 do {									\
-	__assert_write_section_is_protected(s);				\
+	__seqcount_assert_lock_held(s);					\
 									\
-	if (__associated_lock_exists_and_is_preemptible(s))		\
+	if (__seqcount_lock_preemptible(s))				\
 		preempt_disable();					\
 									\
-	write_seqcount_t_begin(__to_seqcount_t(s));			\
+	write_seqcount_t_begin(__seqcount_ptr(s));			\
 } while (0)
 
 static inline void write_seqcount_t_begin(seqcount_t *s)
@@ -504,9 +504,9 @@ static inline void write_seqcount_t_begi
  */
 #define write_seqcount_end(s)						\
 do {									\
-	write_seqcount_t_end(__to_seqcount_t(s));			\
+	write_seqcount_t_end(__seqcount_ptr(s));			\
 									\
-	if (__associated_lock_exists_and_is_preemptible(s))		\
+	if (__seqcount_lock_preemptible(s))				\
 		preempt_enable();					\
 } while (0)
 
@@ -558,7 +558,7 @@ static inline void write_seqcount_t_end(
  *      }
  */
 #define raw_write_seqcount_barrier(s)					\
-	raw_write_seqcount_t_barrier(__to_seqcount_t(s))
+	raw_write_seqcount_t_barrier(__seqcount_ptr(s))
 
 static inline void raw_write_seqcount_t_barrier(seqcount_t *s)
 {
@@ -578,7 +578,7 @@ static inline void raw_write_seqcount_t_
  * will complete successfully and see data older than this.
  */
 #define write_seqcount_invalidate(s)					\
-	write_seqcount_t_invalidate(__to_seqcount_t(s))
+	write_seqcount_t_invalidate(__seqcount_ptr(s))
 
 static inline void write_seqcount_t_invalidate(seqcount_t *s)
 {
@@ -604,7 +604,7 @@ static inline void write_seqcount_t_inva
  * checked with read_seqcount_retry().
  */
 #define raw_read_seqcount_latch(s)					\
-	raw_read_seqcount_t_latch(__to_seqcount_t(s))
+	raw_read_seqcount_t_latch(__seqcount_ptr(s))
 
 static inline int raw_read_seqcount_t_latch(seqcount_t *s)
 {
@@ -695,7 +695,7 @@ static inline int raw_read_seqcount_t_la
  *	patterns to manage the lifetimes of the objects within.
  */
 #define raw_write_seqcount_latch(s)					\
-	raw_write_seqcount_t_latch(__to_seqcount_t(s))
+	raw_write_seqcount_t_latch(__seqcount_ptr(s))
 
 static inline void raw_write_seqcount_t_latch(seqcount_t *s)
 {

Re: [PATCH 1/5] seqlock: s/__SEQ_LOCKDEP/__SEQ_LOCK/g

[Ahmed S. Darwish]

On Wed, Jul 29, 2020 at 03:52:50PM +0200, Peter Zijlstra wrote:
> __SEQ_LOCKDEP() is an expression gate for the
> seqcount_LOCKNAME_t::lock member. Rename it to be about the member,
> not the gate condition.
>
> Later (PREEMPT_RT) patches will make the member available for !LOCKDEP
> configs.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---

Acked-by: Ahmed S. Darwish <a.darwish@linutronix.de>

Re: [PATCH 2/5] seqlock: Fold seqcount_LOCKNAME_t definition

[Ahmed S. Darwish]

On Wed, Jul 29, 2020 at 03:52:51PM +0200, Peter Zijlstra wrote:
> Manual repetition is boring and error prone.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---

...

> +/**
> + * typedef seqcount_LOCKNAME_t - sequence counter with spinlock associated

                                                        ^ associated lock

> + * @seqcount:	The real sequence counter
> + * @lock:	Pointer to the associated spinlock
> + *

              ^ Pointer to the associated write serialization lock

> + * A plain sequence counter with external writer synchronization by a
> + * spinlock. The spinlock is associated to the sequence count in the
> + * static initializer or init function. This enables lockdep to validate
> + * that the write side critical section is properly serialized.

ditto, you forgot to change the associated spinlock language to generic
locks ;-)

Thanks,

--
Ahmed S. Darwish
Linutronix GmbH

Re: [PATCH 5/5] seqcount: More consistent seqprop names

[Ahmed S. Darwish]

On Wed, Jul 29, 2020 at 03:52:54PM +0200, Peter Zijlstra wrote:
> Attempt uniformity and brevity.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---

Acked-by: Ahmed S. Darwish <a.darwish@linutronix.de>

Re: [PATCH 2/5] seqlock: Fold seqcount_LOCKNAME_t definition

[Matthew Wilcox]

On Wed, Jul 29, 2020 at 03:52:51PM +0200, Peter Zijlstra wrote:
> Manual repetition is boring and error prone.

Yes, but generated functions are hard to grep for, and I'm pretty sure
that kernel-doc doesn't know how to expand macros into comments that it
can then extract documentation from.

I've been thinking about how to cure this (mostly in the context
of page-flags.h).  I don't particularly like the C preprocessor, but
m4 is worse and defining our own preprocessing language seems like a
terrible idea.

So I was thinking about moving the current contents of page-flags.h
to include/src/page-flags.h, making linux/page-flags.h depend on
src/page-flags.h and run '$(CPP) -C' to generate it.  I've been a little
busy recently and haven't had time to do more than muse about this, but
I think it might make sense for some of our more heavily macro-templated
header files.

Re: [PATCH 2/5] seqlock: Fold seqcount_LOCKNAME_t definition

[peterz]

On Wed, Jul 29, 2020 at 03:55:07PM +0100, Matthew Wilcox wrote:
> On Wed, Jul 29, 2020 at 03:52:51PM +0200, Peter Zijlstra wrote:
> > Manual repetition is boring and error prone.
> 
> Yes, but generated functions are hard to grep for, and I'm pretty sure
> that kernel-doc doesn't know how to expand macros into comments that it
> can then extract documentation from.
> 
> I've been thinking about how to cure this (mostly in the context
> of page-flags.h).  I don't particularly like the C preprocessor, but
> m4 is worse and defining our own preprocessing language seems like a
> terrible idea.
> 
> So I was thinking about moving the current contents of page-flags.h
> to include/src/page-flags.h, making linux/page-flags.h depend on
> src/page-flags.h and run '$(CPP) -C' to generate it.  I've been a little
> busy recently and haven't had time to do more than muse about this, but
> I think it might make sense for some of our more heavily macro-templated
> header files.

Use ctags and add to scripts/tags.sh.

Re: [PATCH 2/5] seqlock: Fold seqcount_LOCKNAME_t definition

[peterz]

On Wed, Jul 29, 2020 at 05:33:41PM +0200, peterz@infradead.org wrote:
> On Wed, Jul 29, 2020 at 03:55:07PM +0100, Matthew Wilcox wrote:
> > On Wed, Jul 29, 2020 at 03:52:51PM +0200, Peter Zijlstra wrote:
> > > Manual repetition is boring and error prone.
> > 
> > Yes, but generated functions are hard to grep for, and I'm pretty sure
> > that kernel-doc doesn't know how to expand macros into comments that it
> > can then extract documentation from.
> > 
> > I've been thinking about how to cure this (mostly in the context
> > of page-flags.h).  I don't particularly like the C preprocessor, but
> > m4 is worse and defining our own preprocessing language seems like a
> > terrible idea.
> > 
> > So I was thinking about moving the current contents of page-flags.h
> > to include/src/page-flags.h, making linux/page-flags.h depend on
> > src/page-flags.h and run '$(CPP) -C' to generate it.  I've been a little
> > busy recently and haven't had time to do more than muse about this, but
> > I think it might make sense for some of our more heavily macro-templated
> > header files.
> 
> Use ctags and add to scripts/tags.sh.

I'll make the below into a proper patch.

---

diff --git a/scripts/tags.sh b/scripts/tags.sh
index 4e18ae5282a6..63b21881a873 100755
--- a/scripts/tags.sh
+++ b/scripts/tags.sh
@@ -211,6 +211,8 @@ regex_c=(
 	'/\<DEVICE_ATTR_\(RW\|RO\|WO\)(\([[:alnum:]_]\+\)/dev_attr_\2/'
 	'/\<DRIVER_ATTR_\(RW\|RO\|WO\)(\([[:alnum:]_]\+\)/driver_attr_\2/'
 	'/\<\(DEFINE\|DECLARE\)_STATIC_KEY_\(TRUE\|FALSE\)\(\|_RO\)(\([[:alnum:]_]\+\)/\4/'
+	'/^SEQCOUNT_LOCKTYPE(\([^,]*\),[[:space:]]*\([^,]*\),[^)]*)/seqcount_\2_t/'
+	'/^SEQCOUNT_LOCKTYPE(\([^,]*\),[[:space:]]*\([^,]*\),[^)]*)/seqcount_\2_init/'
 )
 regex_kconfig=(
 	'/^[[:blank:]]*\(menu\|\)config[[:blank:]]\+\([[:alnum:]_]\+\)/\2/'