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Commit 383a4bc8 authored by Byungchul Park's avatar Byungchul Park Committed by Ingo Molnar
Browse files

locking/lockdep: Make print_circular_bug() aware of crossrelease 



print_circular_bug() reporting circular bug assumes that target hlock is
owned by the current. However, in crossrelease, target hlock can be
owned by other than the current. So the report format needs to be
changed to reflect the change.

Signed-off-by: default avatarByungchul Park <byungchul.park@lge.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Cc: willy@infradead.org
Link: http://lkml.kernel.org/r/1502089981-21272-9-git-send-email-byungchul.park@lge.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 28a903f6

kernel/locking/lockdep.c

+47 −20
Original line number Diff line number Diff line
@@ -1139,6 +1139,24 @@ print_circular_lock_scenario(struct held_lock *src, 
		printk(KERN_CONT "\n\n");

	}



	if (cross_lock(tgt->instance)) {

		printk(" Possible unsafe locking scenario by crosslock:\n\n");

		printk("       CPU0                    CPU1\n");

		printk("       ----                    ----\n");

		printk("  lock(");

		__print_lock_name(parent);

		printk(KERN_CONT ");\n");

		printk("  lock(");

		__print_lock_name(target);

		printk(KERN_CONT ");\n");

		printk("                               lock(");

		__print_lock_name(source);

		printk(KERN_CONT ");\n");

		printk("                               unlock(");

		__print_lock_name(target);

		printk(KERN_CONT ");\n");

		printk("\n *** DEADLOCK ***\n\n");

	} else {

		printk(" Possible unsafe locking scenario:\n\n");

		printk("       CPU0                    CPU1\n");

		printk("       ----                    ----\n");
@@ -1156,6 +1174,7 @@ print_circular_lock_scenario(struct held_lock *src, 
		printk(KERN_CONT ");\n");

		printk("\n *** DEADLOCK ***\n\n");

	}

}



/*

 * When a circular dependency is detected, print the
@@ -1179,7 +1198,12 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth, 
	pr_warn("%s/%d is trying to acquire lock:\n",

		curr->comm, task_pid_nr(curr));

	print_lock(check_src);



	if (cross_lock(check_tgt->instance))

		pr_warn("\nbut now in release context of a crosslock acquired at the following:\n");

	else

		pr_warn("\nbut task is already holding lock:\n");



	print_lock(check_tgt);

	pr_warn("\nwhich lock already depends on the new lock.\n\n");

	pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
@@ -1197,7 +1221,8 @@ static inline int class_equal(struct lock_list *entry, void *data) 
static noinline int print_circular_bug(struct lock_list *this,

				struct lock_list *target,

				struct held_lock *check_src,

				struct held_lock *check_tgt)

				struct held_lock *check_tgt,

				struct stack_trace *trace)

{

	struct task_struct *curr = current;

	struct lock_list *parent;
@@ -1207,7 +1232,9 @@ static noinline int print_circular_bug(struct lock_list *this, 
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)

		return 0;



	if (!save_trace(&this->trace))

	if (cross_lock(check_tgt->instance))

		this->trace = *trace;

	else if (!save_trace(&this->trace))

		return 0;



	depth = get_lock_depth(target);
@@ -1864,7 +1891,7 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, 
	this.parent = NULL;

	ret = check_noncircular(&this, hlock_class(prev), &target_entry);

	if (unlikely(!ret))

		return print_circular_bug(&this, target_entry, next, prev);

		return print_circular_bug(&this, target_entry, next, prev, trace);

	else if (unlikely(ret < 0))

		return print_bfs_bug(ret);