From e7904a28f5331c21d17af638cb477c83662e3cb6 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Sat, 1 Aug 2015 19:25:08 +0200 Subject: locking/lockdep, sched/core: Implement a better lock pinning scheme The problem with the existing lock pinning is that each pin is of value 1; this mean you can simply unpin if you know its pinned, without having any extra information. This scheme generates a random (16 bit) cookie for each pin and requires this same cookie to unpin. This means you have to keep the cookie in context. No objsize difference for !LOCKDEP kernels. Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Linus Torvalds Cc: Mike Galbraith Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar --- include/linux/lockdep.h | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) (limited to 'include/linux/lockdep.h') diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index d026b190c530..cf9bf9612702 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -354,8 +354,13 @@ extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask); extern void lockdep_clear_current_reclaim_state(void); extern void lockdep_trace_alloc(gfp_t mask); -extern void lock_pin_lock(struct lockdep_map *lock); -extern void lock_unpin_lock(struct lockdep_map *lock); +struct pin_cookie { unsigned int val; }; + +#define NIL_COOKIE (struct pin_cookie){ .val = 0U, } + +extern struct pin_cookie lock_pin_lock(struct lockdep_map *lock); +extern void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie); +extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie); # define INIT_LOCKDEP .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0, @@ -371,8 +376,9 @@ extern void lock_unpin_lock(struct lockdep_map *lock); #define lockdep_recursing(tsk) ((tsk)->lockdep_recursion) -#define lockdep_pin_lock(l) lock_pin_lock(&(l)->dep_map) -#define lockdep_unpin_lock(l) lock_unpin_lock(&(l)->dep_map) +#define lockdep_pin_lock(l) lock_pin_lock(&(l)->dep_map) +#define lockdep_repin_lock(l,c) lock_repin_lock(&(l)->dep_map, (c)) +#define lockdep_unpin_lock(l,c) lock_unpin_lock(&(l)->dep_map, (c)) #else /* !CONFIG_LOCKDEP */ @@ -425,8 +431,13 @@ struct lock_class_key { }; #define lockdep_recursing(tsk) (0) -#define lockdep_pin_lock(l) do { (void)(l); } while (0) -#define lockdep_unpin_lock(l) do { (void)(l); } while (0) +struct pin_cookie { }; + +#define NIL_COOKIE (struct pin_cookie){ } + +#define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; }) +#define lockdep_repin_lock(l, c) do { (void)(l); (void)(c); } while (0) +#define lockdep_unpin_lock(l, c) do { (void)(l); (void)(c); } while (0) #endif /* !LOCKDEP */ -- cgit v1.2.3-59-g8ed1b