Messages in this thread Patch in this message | | | From | Yuyang Du <> | Subject | [PATCH v3 16/30] locking/lockdep: Use lock type enum to explicitly specify read or write locks | Date | Fri, 28 Jun 2019 17:15:14 +0800 |
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Add an enum to formally quantify lock types. No functional change.
Signed-off-by: Yuyang Du <duyuyang@gmail.com> --- include/linux/lockdep.h | 27 ++++++++++++++++++++------- include/linux/rcupdate.h | 2 +- kernel/locking/lockdep.c | 19 +++++++++++-------- 3 files changed, 32 insertions(+), 16 deletions(-)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 981718b..eb26e93 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -353,10 +353,18 @@ static inline int lockdep_match_key(struct lockdep_map *lock, * * Values for "read": * - * 0: exclusive (write) acquire - * 1: read-acquire (no recursion allowed) - * 2: read-acquire with same-instance recursion allowed - * + * LOCK_TYPE_EXCLUSIVE (LOCK_TYPE_WRITE): exclusive (write) acquire + * LOCK_TYPE_READ: read-acquire (no recursion allowed) + * LOCK_TYPE_RECURSIVE: read-acquire with same-instance recursion allowed + */ +enum lock_type { + LOCK_TYPE_EXCLUSIVE = 0, + LOCK_TYPE_WRITE = 0, + LOCK_TYPE_READ, + LOCK_TYPE_RECURSIVE, +}; + +/* * Values for check: * * 0: simple checks (freeing, held-at-exit-time, etc.) @@ -602,9 +610,14 @@ static inline void print_irqtrace_events(struct task_struct *curr) * on the per lock-class debug mode: */ -#define lock_acquire_exclusive(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, n, i) -#define lock_acquire_shared(l, s, t, n, i) lock_acquire(l, s, t, 1, 1, n, i) -#define lock_acquire_shared_recursive(l, s, t, n, i) lock_acquire(l, s, t, 2, 1, n, i) +#define lock_acquire_exclusive(l, s, t, n, i) \ + lock_acquire(l, s, t, LOCK_TYPE_EXCLUSIVE, 1, n, i) + +#define lock_acquire_shared(l, s, t, n, i) \ + lock_acquire(l, s, t, LOCK_TYPE_READ, 1, n, i) + +#define lock_acquire_shared_recursive(l, s, t, n, i) \ + lock_acquire(l, s, t, LOCK_TYPE_RECURSIVE, 1, n, i) #define spin_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i) #define spin_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index b25d208..d0279da 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -205,7 +205,7 @@ static inline void destroy_rcu_head_on_stack(struct rcu_head *head) { } static inline void rcu_lock_acquire(struct lockdep_map *map) { - lock_acquire(map, 0, 0, 2, 0, NULL, _THIS_IP_); + lock_acquire(map, 0, 0, LOCK_TYPE_RECURSIVE, 0, NULL, _THIS_IP_); } static inline void rcu_lock_release(struct lockdep_map *map) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 3b655fd..3c97d71 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -2356,7 +2356,10 @@ static inline void inc_chains(void) * (Note that this has to be done separately, because the graph cannot * detect such classes of deadlocks.) * - * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read + * Returns: + * 0: on deadlock detected; + * 1: on OK; + * LOCK_TYPE_RECURSIVE: on recursive read */ static int check_deadlock_current(struct task_struct *curr, struct held_lock *next) @@ -2378,15 +2381,15 @@ static inline void inc_chains(void) * Allow read-after-read recursion of the same * lock class (i.e. read_lock(lock)+read_lock(lock)): */ - if ((next->read == 2) && prev->read) - return 2; + if ((next->read == LOCK_TYPE_RECURSIVE) && prev->read) + return LOCK_TYPE_RECURSIVE; /* * We're holding the nest_lock, which serializes this lock's * nesting behaviour. */ if (nest) - return 2; + return LOCK_TYPE_RECURSIVE; print_deadlock_bug(curr, prev, next); return 0; @@ -2489,7 +2492,7 @@ static inline void inc_chains(void) * write-lock never takes any other locks, then the reads are * equivalent to a NOP. */ - if (next->read == 2 || prev->read == 2) + if (next->read == LOCK_TYPE_RECURSIVE || prev->read == LOCK_TYPE_RECURSIVE) return 1; if (!trace->nr_entries && !save_trace(trace)) @@ -2869,7 +2872,7 @@ static int validate_chain(struct task_struct *curr, struct held_lock *next, * chain, and if it's not a second recursive-read lock. If * not, there is no need to check further. */ - if (!(chain->depth > 1 && ret != 2)) + if (!(chain->depth > 1 && ret != LOCK_TYPE_RECURSIVE)) goto out_unlock; } @@ -2878,7 +2881,7 @@ static int validate_chain(struct task_struct *curr, struct held_lock *next, * added: */ if (chain) { - if (hlock->read != 2 && hlock->check) { + if (hlock->read != LOCK_TYPE_RECURSIVE && hlock->check) { int distance = curr->lockdep_depth - depth + 1; if (!check_prev_add(curr, hlock, next, distance, @@ -4132,7 +4135,7 @@ static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip) curr->curr_chain_key = hlock->prev_chain_key; WARN(hlock->read, "downgrading a read lock"); - hlock->read = 1; + hlock->read = LOCK_TYPE_READ; hlock->acquire_ip = ip; if (reacquire_held_locks(curr, depth, i, &merged)) -- 1.8.3.1
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