If a dynamic amount of locks needs to be pinned in the same context, it is impractical to have a cookie per lock. Make the cookie generator accessible, so that such a group of locks can be (re-)pinned with just one (shared) cookie.
Signed-off-by: Jan H. Schönherr <[email protected]> --- include/linux/lockdep.h | 2 ++ kernel/locking/lockdep.c | 21 +++++++++++++++------ 2 files changed, 17 insertions(+), 6 deletions(-) diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index d93a5ec3077f..06aee3386071 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -363,6 +363,7 @@ struct pin_cookie { unsigned int val; }; #define NIL_COOKIE (struct pin_cookie){ .val = 0U, } +struct pin_cookie lockdep_cookie(void); 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); @@ -452,6 +453,7 @@ struct pin_cookie { }; #define NIL_COOKIE (struct pin_cookie){ } +#define lockdep_cookie() (NIL_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) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index e406c5fdb41e..76aae27e1736 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3729,6 +3729,20 @@ static int __lock_is_held(const struct lockdep_map *lock, int read) return 0; } +struct pin_cookie lockdep_cookie(void) +{ + struct pin_cookie cookie; + + /* + * Grab 16bits of randomness; this is sufficient to not + * be guessable and still allows some pin nesting in + * our u32 pin_count. + */ + cookie.val = 1 + (prandom_u32() >> 16); + + return cookie; +} + static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock) { struct pin_cookie cookie = NIL_COOKIE; @@ -3742,12 +3756,7 @@ static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock) struct held_lock *hlock = curr->held_locks + i; if (match_held_lock(hlock, lock)) { - /* - * Grab 16bits of randomness; this is sufficient to not - * be guessable and still allows some pin nesting in - * our u32 pin_count. - */ - cookie.val = 1 + (prandom_u32() >> 16); + cookie = lockdep_cookie(); hlock->pin_count += cookie.val; return cookie; } -- 2.9.3.1.gcba166c.dirty
