Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking fixes from Ingo Molnar:
 "Two lockdep fixes"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  lockdep: Fix lock_chain::base size
  locking/lockdep: Fix ->irq_context calculation

3 files changed, 41 insertions, 6 deletions

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index d026b190c530..d10ef06971b5 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -196,9 +196,11 @@ struct lock_list {
  * We record lock dependency chains, so that we can cache them:
  */
 struct lock_chain {
-        u8                              irq_context;
-        u8                              depth;
-        u16                             base;
+        /* see BUILD_BUG_ON()s in lookup_chain_cache() */
+        unsigned int                    irq_context :  2,
+                                        depth       :  6,
+                                        base        : 24;
+        /* 4 byte hole */
         struct hlist_node               entry;
         u64                             chain_key;
 };
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index ed9410936a22..78c1c0ee6dc1 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2176,15 +2176,37 @@ cache_hit:
         chain->irq_context = hlock->irq_context;
         i = get_first_held_lock(curr, hlock);
         chain->depth = curr->lockdep_depth + 1 - i;
+
+        BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
+        BUILD_BUG_ON((1UL << 6)  <= ARRAY_SIZE(curr->held_locks));
+        BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
+
         if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
                 chain->base = nr_chain_hlocks;
-                nr_chain_hlocks += chain->depth;
                 for (j = 0; j < chain->depth - 1; j++, i++) {
                         int lock_id = curr->held_locks[i].class_idx - 1;
                         chain_hlocks[chain->base + j] = lock_id;
                 }
                 chain_hlocks[chain->base + j] = class - lock_classes;
         }
+
+        if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
+                nr_chain_hlocks += chain->depth;
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+        /*
+         * Important for check_no_collision().
+         */
+        if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
+                if (debug_locks_off_graph_unlock())
+                        return 0;
+
+                print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
+                dump_stack();
+                return 0;
+        }
+#endif
+
         hlist_add_head_rcu(&chain->entry, hash_head);
         debug_atomic_inc(chain_lookup_misses);
         inc_chains();
@@ -2932,6 +2954,11 @@ static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
         return 1;
 }
 
+static inline unsigned int task_irq_context(struct task_struct *task)
+{
+        return 2 * !!task->hardirq_context + !!task->softirq_context;
+}
+
 static int separate_irq_context(struct task_struct *curr,
                 struct held_lock *hlock)
 {
@@ -2940,8 +2967,6 @@ static int separate_irq_context(struct task_struct *curr,
         /*
          * Keep track of points where we cross into an interrupt context:
          */
-        hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
-                                curr->softirq_context;
         if (depth) {
                 struct held_lock *prev_hlock;
 
@@ -2973,6 +2998,11 @@ static inline int mark_irqflags(struct task_struct *curr,
         return 1;
 }
 
+static inline unsigned int task_irq_context(struct task_struct *task)
+{
+        return 0;
+}
+
 static inline int separate_irq_context(struct task_struct *curr,
                 struct held_lock *hlock)
 {
@@ -3241,6 +3271,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
         hlock->acquire_ip = ip;
         hlock->instance = lock;
         hlock->nest_lock = nest_lock;
+        hlock->irq_context = task_irq_context(curr);
         hlock->trylock = trylock;
         hlock->read = read;
         hlock->check = check;
diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
index dbb61a302548..a0f61effad25 100644
--- a/kernel/locking/lockdep_proc.c
+++ b/kernel/locking/lockdep_proc.c
@@ -141,6 +141,8 @@ static int lc_show(struct seq_file *m, void *v)
         int i;
 
         if (v == SEQ_START_TOKEN) {
+                if (nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)
+                        seq_printf(m, "(buggered) ");
                 seq_printf(m, "all lock chains:\n");
                 return 0;
         }