[PATCH RFC v6 07/21] dept: Apply Dept to seqlock

Byungchul Park
2022-05-04T08:49:29Z

Makes Dept able to track dependencies by seqlock with adding wait
annotation on read side of seqlock.

Signed-off-by: Byungchul Park <byungchul.park@lge.com>
---
include/linux/seqlock.h | 60 +++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 58 insertions(+), 2 deletions(-)

diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index 37ded6b..47c3379 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -23,6 +23,23 @@

#include <asm/processor.h>

+#ifdef CONFIG_DEPT
+#define DEPT_EVT_ALL ((1UL << DEPT_MAX_SUBCLASSES_EVT) - 1)
+#define dept_seq_wait(m, ip) dept_wait(m, DEPT_EVT_ALL, ip, __func__, 0)
+#define dept_seq_writebegin(m, ip) \
+do { \
+ dept_ecxt_enter(m, 1UL, ip, __func__, "write_seqcount_end", 0);\
+} while (0)
+#define dept_seq_writeend(m, ip) \
+do { \
+ dept_ecxt_exit(m, 1UL, ip); \
+} while (0)
+#else
+#define dept_seq_wait(m, ip) do { } while (0)
+#define dept_seq_writebegin(m, ip) do { } while (0)
+#define dept_seq_writeend(m, ip) do { } while (0)
+#endif
+
/*
* The seqlock seqcount_t interface does not prescribe a precise sequence of
* read begin/retry/end. For readers, typically there is a call to
@@ -82,7 +99,8 @@ static inline void __seqcount_init(seqcount_t *s, const char *name,
#ifdef CONFIG_DEBUG_LOCK_ALLOC

# define SEQCOUNT_DEP_MAP_INIT(lockname) \
- .dep_map = { .name = #lockname }
+ .dep_map = { .name = #lockname, \
+ .dmap = DEPT_MAP_INITIALIZER(lockname) }

/**
* seqcount_init() - runtime initializer for seqcount_t
@@ -148,7 +166,7 @@ static inline void seqcount_lockdep_reader_access(const seqcount_t *s)
* This lock-unlock technique must be implemented for all of PREEMPT_RT
* sleeping locks. See Documentation/locking/locktypes.rst
*/
-#if defined(CONFIG_LOCKDEP) || defined(CONFIG_PREEMPT_RT)
+#if defined(CONFIG_LOCKDEP) || defined(CONFIG_DEPT) || defined(CONFIG_PREEMPT_RT)
#define __SEQ_LOCK(expr) expr
#else
#define __SEQ_LOCK(expr)
@@ -203,6 +221,22 @@ static inline void seqcount_lockdep_reader_access(const seqcount_t *s)
__SEQ_LOCK(locktype *lock); \
} seqcount_##lockname##_t; \
\
+static __always_inline void \
+__seqprop_##lockname##_wait(const seqcount_##lockname##_t *s) \
+{ \
+ __SEQ_LOCK(dept_seq_wait(&(lockmember)->dep_map.dmap, _RET_IP_));\
+} \
+ \
+static __always_inline void \
+__seqprop_##lockname##_writebegin(const seqcount_##lockname##_t *s) \
+{ \
+} \
+ \
+static __always_inline void \
+__seqprop_##lockname##_writeend(const seqcount_##lockname##_t *s) \
+{ \
+} \
+ \
static __always_inline seqcount_t * \
__seqprop_##lockname##_ptr(seqcount_##lockname##_t *s) \
{ \
@@ -271,6 +305,21 @@ static inline void __seqprop_assert(const seqcount_t *s)
lockdep_assert_preemption_disabled();
}

+static inline void __seqprop_wait(seqcount_t *s)
+{
+ dept_seq_wait(&s->dep_map.dmap, _RET_IP_);
+}
+
+static inline void __seqprop_writebegin(seqcount_t *s)
+{
+ dept_seq_writebegin(&s->dep_map.dmap, _RET_IP_);
+}
+
+static inline void __seqprop_writeend(seqcount_t *s)
+{
+ dept_seq_writeend(&s->dep_map.dmap, _RET_IP_);
+}
+
#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))
@@ -311,6 +360,9 @@ static inline void __seqprop_assert(const seqcount_t *s)
#define seqprop_sequence(s) __seqprop(s, sequence)
#define seqprop_preemptible(s) __seqprop(s, preemptible)
#define seqprop_assert(s) __seqprop(s, assert)
+#define seqprop_dept_wait(s) __seqprop(s, wait)
+#define seqprop_dept_writebegin(s) __seqprop(s, writebegin)
+#define seqprop_dept_writeend(s) __seqprop(s, writeend)

/**
* __read_seqcount_begin() - begin a seqcount_t read section w/o barrier
@@ -360,6 +412,7 @@ static inline void __seqprop_assert(const seqcount_t *s)
#define read_seqcount_begin(s) \
({ \
seqcount_lockdep_reader_access(seqprop_ptr(s)); \
+ seqprop_dept_wait(s); \
raw_read_seqcount_begin(s); \
})

@@ -512,6 +565,7 @@ static inline void do_raw_write_seqcount_end(seqcount_t *s)
preempt_disable(); \
\
do_write_seqcount_begin_nested(seqprop_ptr(s), subclass); \
+ seqprop_dept_writebegin(s); \
} while (0)

static inline void do_write_seqcount_begin_nested(seqcount_t *s, int subclass)
@@ -538,6 +592,7 @@ static inline void do_write_seqcount_begin_nested(seqcount_t *s, int subclass)
preempt_disable(); \
\
do_write_seqcount_begin(seqprop_ptr(s)); \
+ seqprop_dept_writebegin(s); \
} while (0)

static inline void do_write_seqcount_begin(seqcount_t *s)
@@ -554,6 +609,7 @@ static inline void do_write_seqcount_begin(seqcount_t *s)
*/
#define write_seqcount_end(s) \
do { \
+ seqprop_dept_writeend(s); \
do_write_seqcount_end(seqprop_ptr(s)); \
\
if (seqprop_preemptible(s)) \
--
1.9.1