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[PATCH] lockdep: add graph depth information to /proc/lockdep

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Generate locking graph information into /proc/lockdep, for lock hierarchy
documentation and visualization purposes.

sample output:

 c089fd5c OPS:     138 FD:   14 BD:    1 --..: &tty->termios_mutex
  -> [c07a3430] tty_ldisc_lock
  -> [c07a37f0] &port_lock_key
  -> [c07afdc0] &rq->rq_lock_key#2

The lock classes listed are all the first-hop lock dependencies that
lockdep has seen so far.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jason Baron
2007-02-10 01:44:59 -08:00
committed by Linus Torvalds
parent 381a229209
commit 068135e635
3 changed files with 42 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
kernel/lockdep.c
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@@ -490,7 +490,7 @@ static void print_lock_dependencies(struct lock_class *class, int depth)
* Add a new dependency to the head of the list:
*/
static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
struct list_head *head, unsigned long ip)
struct list_head *head, unsigned long ip, int distance)
{
struct lock_list *entry;
/*
@@ -502,6 +502,7 @@ static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
return 0;
entry->class = this;
entry->distance = distance;
if (!save_trace(&entry->trace))
return 0;
@@ -906,7 +907,7 @@ check_deadlock(struct task_struct *curr, struct held_lock *next,
*/
static int
check_prev_add(struct task_struct *curr, struct held_lock *prev,
struct held_lock *next)
struct held_lock *next, int distance)
{
struct lock_list *entry;
int ret;
@@ -984,8 +985,11 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
* L2 added to its dependency list, due to the first chain.)
*/
list_for_each_entry(entry, &prev->class->locks_after, entry) {
if (entry->class == next->class)
if (entry->class == next->class) {
if (distance == 1)
entry->distance = 1;
return 2;
}
}
/*
@@ -993,12 +997,13 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
* to the previous lock's dependency list:
*/
ret = add_lock_to_list(prev->class, next->class,
&prev->class->locks_after, next->acquire_ip);
&prev->class->locks_after, next->acquire_ip, distance);
if (!ret)
return 0;
ret = add_lock_to_list(next->class, prev->class,
&next->class->locks_before, next->acquire_ip);
&next->class->locks_before, next->acquire_ip, distance);
if (!ret)
return 0;
@@ -1046,13 +1051,14 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
goto out_bug;
for (;;) {
int distance = curr->lockdep_depth - depth + 1;
hlock = curr->held_locks + depth-1;
/*
* Only non-recursive-read entries get new dependencies
* added:
*/
if (hlock->read != 2) {
if (!check_prev_add(curr, hlock, next))
if (!check_prev_add(curr, hlock, next, distance))
return 0;
/*
* Stop after the first non-trylock entry,
@@ -2779,4 +2785,3 @@ void debug_show_held_locks(struct task_struct *task)
}
EXPORT_SYMBOL_GPL(debug_show_held_locks);