Commit-ID: ace35a7ac493d4284a57ad807579011bebba891c Gitweb: https://git.kernel.org/tip/ace35a7ac493d4284a57ad807579011bebba891c Author: Bart Van Assche <bvanass...@acm.org> AuthorDate: Thu, 14 Feb 2019 15:00:47 -0800 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Thu, 28 Feb 2019 07:55:44 +0100
locking/lockdep: Reuse list entries that are no longer in use Instead of abandoning elements of list_entries[] that are no longer in use, make alloc_list_entry() reuse array elements that have been freed. Signed-off-by: Bart Van Assche <bvanass...@acm.org> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Johannes Berg <johan...@sipsolutions.net> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Waiman Long <long...@redhat.com> Cc: Will Deacon <will.dea...@arm.com> Cc: johannes.b...@intel.com Cc: t...@kernel.org Link: https://lkml.kernel.org/r/20190214230058.196511-13-bvanass...@acm.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/locking/lockdep.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 8ecf355dd163..2c6d0b67e7b6 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -45,6 +45,7 @@ #include <linux/hash.h> #include <linux/ftrace.h> #include <linux/stringify.h> +#include <linux/bitmap.h> #include <linux/bitops.h> #include <linux/gfp.h> #include <linux/random.h> @@ -132,6 +133,7 @@ static inline int debug_locks_off_graph_unlock(void) unsigned long nr_list_entries; static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; +static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES); /* * All data structures here are protected by the global debug_lock. @@ -907,7 +909,10 @@ out_set_class_cache: */ static struct lock_list *alloc_list_entry(void) { - if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { + int idx = find_first_zero_bit(list_entries_in_use, + ARRAY_SIZE(list_entries)); + + if (idx >= ARRAY_SIZE(list_entries)) { if (!debug_locks_off_graph_unlock()) return NULL; @@ -915,7 +920,9 @@ static struct lock_list *alloc_list_entry(void) dump_stack(); return NULL; } - return list_entries + nr_list_entries++; + nr_list_entries++; + __set_bit(idx, list_entries_in_use); + return list_entries + idx; } /* @@ -1019,7 +1026,7 @@ static inline void mark_lock_accessed(struct lock_list *lock, unsigned long nr; nr = lock - list_entries; - WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ + WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */ lock->parent = parent; lock->class->dep_gen_id = lockdep_dependency_gen_id; } @@ -1029,7 +1036,7 @@ static inline unsigned long lock_accessed(struct lock_list *lock) unsigned long nr; nr = lock - list_entries; - WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ + WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */ return lock->class->dep_gen_id == lockdep_dependency_gen_id; } @@ -4276,13 +4283,13 @@ static void zap_class(struct pending_free *pf, struct lock_class *class) * Remove all dependencies this lock is * involved in: */ - for (i = 0, entry = list_entries; i < nr_list_entries; i++, entry++) { + for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) { + entry = list_entries + i; if (entry->class != class && entry->links_to != class) continue; + __clear_bit(i, list_entries_in_use); + nr_list_entries--; list_del_rcu(&entry->entry); - /* Clear .class and .links_to to avoid double removal. */ - WRITE_ONCE(entry->class, NULL); - WRITE_ONCE(entry->links_to, NULL); } if (list_empty(&class->locks_after) && list_empty(&class->locks_before)) { @@ -4596,6 +4603,7 @@ void __init lockdep_init(void) (sizeof(lock_classes) + sizeof(classhash_table) + sizeof(list_entries) + + sizeof(list_entries_in_use) + sizeof(chainhash_table) + sizeof(delayed_free) #ifdef CONFIG_PROVE_LOCKING
