Deadlock checks are performed at two places: - Within current's held lock stack, check for lock recursion deadlock. - Within dependency graph, check for lock inversion deadlock.
Rename the two relevant functions for later use. Plus, with recursive-read locks, only a dependency circle in graph is not a sufficient condition for lock inversion deadlocks anymore, so check_noncircular() is not entirely accurate. No functional change. Signed-off-by: Yuyang Du <[email protected]> --- kernel/locking/lockdep.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 341f521..e30e9e4 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1714,8 +1714,8 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class) * Print an error and return 0 if it does. */ static noinline int -check_noncircular(struct held_lock *src, struct held_lock *target, - struct lock_trace *trace) +check_deadlock_graph(struct held_lock *src, struct held_lock *target, + struct lock_trace *trace) { int ret; struct lock_list *uninitialized_var(target_entry); @@ -2302,7 +2302,8 @@ static inline void inc_chains(void) } /* - * Check whether we are holding such a class already. + * Check whether we are holding such a class already in the current + * held lock stack. * * (Note that this has to be done separately, because the graph cannot * detect such classes of deadlocks.) @@ -2310,7 +2311,7 @@ static inline void inc_chains(void) * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read */ static int -check_deadlock(struct task_struct *curr, struct held_lock *next) +check_deadlock_current(struct task_struct *curr, struct held_lock *next) { struct held_lock *prev; struct held_lock *nest = NULL; @@ -2394,7 +2395,7 @@ static inline void inc_chains(void) /* * Prove that the new <prev> -> <next> dependency would not - * create a circular dependency in the graph. (We do this by + * create a deadlock scenario in the graph. (We do this by * a breadth-first search into the graph starting at <next>, * and check whether we can reach <prev>.) * @@ -2402,7 +2403,7 @@ static inline void inc_chains(void) * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes * in the graph whose neighbours are to be checked. */ - ret = check_noncircular(next, prev, trace); + ret = check_deadlock_graph(next, prev, trace); if (unlikely(ret <= 0)) return 0; @@ -2878,7 +2879,7 @@ static int validate_chain(struct task_struct *curr, * The simple case: does the current hold the same lock * already? */ - int ret = check_deadlock(curr, hlock); + int ret = check_deadlock_current(curr, hlock); if (!ret) return 0; -- 1.8.3.1
