Messages in this thread Patch in this message | | | From | Yuyang Du <> | Subject | [PATCH v2 02/17] locking/lockdep: Add read-write type for dependency | Date | Thu, 16 May 2019 16:00:00 +0800 |
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Direct dependency needs to keep track of its locks' read-write types. A union field is added to lock_list struct so the type is stored there as this:
lock_type[1] (u16), lock_type[0] (u16)
or:
dep_type (int)
where value:
0: exclusive / write 1: read 2: recursive read
Note that (int) dep_type value may vary with different architectural endianness, so use helper functions to operate on these types.
Signed-off-by: Yuyang Du <duyuyang@gmail.com> --- include/linux/lockdep.h | 12 ++++++++++++ kernel/locking/lockdep.c | 34 +++++++++++++++++++++++++++++++--- kernel/locking/lockdep_internals.h | 3 +++ 3 files changed, 46 insertions(+), 3 deletions(-)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 1009c47..bc09c85 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -195,6 +195,18 @@ struct lock_list { struct lock_class *links_to; struct lock_trace trace; int distance; + /* + * This field keeps track of the read-write type of this dependency. + * + * With L1 -> L2: + * + * lock_type[0] stores the type of L1, while lock_type[1] stores the + * type of L2. + */ + union { + int dep_type; + u16 lock_type[2]; + }; /* * The parent field is used to implement breadth-first search, and the diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index fb6be63..e7eedbf 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1225,7 +1225,7 @@ static struct lock_list *alloc_list_entry(void) static int add_lock_to_list(struct lock_class *this, struct lock_class *links_to, struct list_head *head, unsigned long ip, int distance, - struct lock_trace *trace) + struct lock_trace *trace, int dep_type) { struct lock_list *entry; /* @@ -1240,6 +1240,8 @@ static int add_lock_to_list(struct lock_class *this, entry->links_to = links_to; entry->distance = distance; entry->trace = *trace; + entry->dep_type = dep_type; + /* * Both allocation and removal are done under the graph lock; but * iteration is under RCU-sched; see look_up_lock_class() and @@ -1677,6 +1679,30 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class) return ret; } +static inline int get_dep_type(struct held_lock *lock1, struct held_lock *lock2) +{ + /* + * With dependency lock1 -> lock2: + * + * lock_type[0] is lock1, while lock_type[1] is lock2. + * + * Avoid architectural endianness difference composing dep_type. + */ + u16 type[2] = { lock1->read, lock2->read }; + + return *(int *)type; +} + +static inline int get_lock_type1(struct lock_list *lock) +{ + return lock->lock_type[0]; +} + +static inline int get_lock_type2(struct lock_list *lock) +{ + return lock->lock_type[1]; +} + /* * Check that the dependency graph starting at <src> can lead to * <target> or not. Print an error and return 0 if it does. @@ -2446,14 +2472,16 @@ static inline void inc_chains(void) */ ret = add_lock_to_list(hlock_class(next), hlock_class(prev), &hlock_class(prev)->locks_after, - next->acquire_ip, distance, trace); + next->acquire_ip, distance, trace, + get_dep_type(prev, next)); if (!ret) return 0; ret = add_lock_to_list(hlock_class(prev), hlock_class(next), &hlock_class(next)->locks_before, - next->acquire_ip, distance, trace); + next->acquire_ip, distance, trace, + get_dep_type(next, prev)); if (!ret) return 0; diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h index 150ec3f..c287bcb 100644 --- a/kernel/locking/lockdep_internals.h +++ b/kernel/locking/lockdep_internals.h @@ -26,6 +26,9 @@ enum lock_usage_bit { #define LOCK_USAGE_DIR_MASK 2 #define LOCK_USAGE_STATE_MASK (~(LOCK_USAGE_READ_MASK | LOCK_USAGE_DIR_MASK)) +#define LOCK_TYPE_BITS 16 +#define LOCK_TYPE_MASK 0xFFFF + /* * Usage-state bitmasks: */ -- 1.8.3.1
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