The patch titled
lockdep: more unlock-on-error fixes
has been removed from the -mm tree. Its filename was
lockdep-more-unlock-on-error-fixes.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: lockdep: more unlock-on-error fixes
From: Jarek Poplawski <jarkao2@xxxxx>
- returns after DEBUG_LOCKS_WARN_ON added in 3 places
- debug_locks checking after lookup_chain_cache() added in
__lock_acquire()
- locking for testing and changing global variable max_lockdep_depth
added in __lock_acquire()
My __acquire_lock() cleanup introduced a locking bug: on SMP systems we'd
release a non-owned graph lock. Fix this by moving the graph unlock back,
and by leaving the max_lockdep_depth variable update possibly racy. (we
dont care, it's just statistics)
Also add some minimal debugging code to graph_unlock()/graph_lock(),
which caught this locking bug.
Signed-off-by: Jarek Poplawski <jarkao2@xxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/lockdep.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)
diff -puN kernel/lockdep.c~lockdep-more-unlock-on-error-fixes kernel/lockdep.c
--- a/kernel/lockdep.c~lockdep-more-unlock-on-error-fixes
+++ a/kernel/lockdep.c
@@ -70,6 +70,9 @@ static int graph_lock(void)
static inline int graph_unlock(void)
{
+ if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
+ return DEBUG_LOCKS_WARN_ON(1);
+
__raw_spin_unlock(&lockdep_lock);
return 0;
}
@@ -712,6 +715,9 @@ find_usage_backwards(struct lock_class *
struct lock_list *entry;
int ret;
+ if (!__raw_spin_is_locked(&lockdep_lock))
+ return DEBUG_LOCKS_WARN_ON(1);
+
if (depth > max_recursion_depth)
max_recursion_depth = depth;
if (depth >= RECURSION_LIMIT)
@@ -1293,7 +1299,8 @@ out_unlock_set:
if (!subclass || force)
lock->class_cache = class;
- DEBUG_LOCKS_WARN_ON(class->subclass != subclass);
+ if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
+ return NULL;
return class;
}
@@ -1308,7 +1315,8 @@ static inline int lookup_chain_cache(u64
struct list_head *hash_head = chainhashentry(chain_key);
struct lock_chain *chain;
- DEBUG_LOCKS_WARN_ON(!irqs_disabled());
+ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+ return 0;
/*
* We can walk it lock-free, because entries only get added
* to the hash:
@@ -1394,7 +1402,9 @@ static void check_chain_key(struct task_
return;
}
id = hlock->class - lock_classes;
- DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS);
+ if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
+ return;
+
if (prev_hlock && (prev_hlock->irq_context !=
hlock->irq_context))
chain_key = 0;
@@ -2205,7 +2215,11 @@ out_calc_hash:
if (!check_prevs_add(curr, hlock))
return 0;
graph_unlock();
- }
+ } else
+ /* after lookup_chain_cache(): */
+ if (unlikely(!debug_locks))
+ return 0;
+
curr->lockdep_depth++;
check_chain_key(curr);
if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
@@ -2214,6 +2228,7 @@ out_calc_hash:
printk("turning off the locking correctness validator.\n");
return 0;
}
+
if (unlikely(curr->lockdep_depth > max_lockdep_depth))
max_lockdep_depth = curr->lockdep_depth;
_
Patches currently in -mm which might be from jarkao2@xxxxx are
origin.patch
-
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