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Commit 86cffb80 authored by Bart Van Assche's avatar Bart Van Assche Committed by Ingo Molnar
Browse files

locking/lockdep: Make zap_class() remove all matching lock order entries 



Make sure that all lock order entries that refer to a class are removed
from the list_entries[] array when a kernel module is unloaded.

Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-7-bvanassche@acm.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 09329d1c

include/linux/lockdep.h

+1 −0
Original line number Diff line number Diff line
@@ -178,6 +178,7 @@ static inline void lockdep_copy_map(struct lockdep_map *to, 
struct lock_list {

	struct list_head		entry;

	struct lock_class		*class;

	struct lock_class		*links_to;

	struct stack_trace		trace;

	int				distance;

kernel/locking/lockdep.c

+13 −6
Original line number Diff line number Diff line
@@ -859,7 +859,8 @@ static struct lock_list *alloc_list_entry(void) 
/*

 * Add a new dependency to the head of the list:

 */

static int add_lock_to_list(struct lock_class *this, struct list_head *head,

static int add_lock_to_list(struct lock_class *this,

			    struct lock_class *links_to, struct list_head *head,

			    unsigned long ip, int distance,

			    struct stack_trace *trace)

{
@@ -873,6 +874,7 @@ static int add_lock_to_list(struct lock_class *this, struct list_head *head, 
		return 0;



	entry->class = this;

	entry->links_to = links_to;

	entry->distance = distance;

	entry->trace = *trace;

	/*
@@ -1907,14 +1909,14 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, 
	 * Ok, all validations passed, add the new lock

	 * to the previous lock's dependency list:

	 */

	ret = add_lock_to_list(hlock_class(next),

	ret = add_lock_to_list(hlock_class(next), hlock_class(prev),

			       &hlock_class(prev)->locks_after,

			       next->acquire_ip, distance, trace);



	if (!ret)

		return 0;



	ret = add_lock_to_list(hlock_class(prev),

	ret = add_lock_to_list(hlock_class(prev), hlock_class(next),

			       &hlock_class(next)->locks_before,

			       next->acquire_ip, distance, trace);

	if (!ret)
@@ -4107,15 +4109,20 @@ void lockdep_reset(void) 
 */

static void zap_class(struct lock_class *class)

{

	struct lock_list *entry;

	int i;



	/*

	 * Remove all dependencies this lock is

	 * involved in:

	 */

	for (i = 0; i < nr_list_entries; i++) {

		if (list_entries[i].class == class)

			list_del_rcu(&list_entries[i].entry);

	for (i = 0, entry = list_entries; i < nr_list_entries; i++, entry++) {

		if (entry->class != class && entry->links_to != class)

			continue;

		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);

	}

	/*

	 * Unhash the class and remove it from the all_lock_classes list: