lockdep: add lock_class information to lock_chain and output it

This patch records array of lock_class into lock_chain, and export
lock_chain information via /proc/lockdep_chains.

It is based on x86/master branch of git-x86 tree, and has been tested
on x86_64 platform.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 35 insertions, 3 deletions

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 81a4e4a3f087..a796f1f38ac5 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -1458,7 +1458,14 @@ out_bug:
 }
 
 unsigned long nr_lock_chains;
-static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
+struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
+atomic_t nr_chain_hlocks;
+static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
+
+struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
+{
+        return lock_classes + chain_hlocks[chain->base + i];
+}
 
 /*
  * Look up a dependency chain. If the key is not present yet then
@@ -1466,10 +1473,15 @@ static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
  * validated. If the key is already hashed, return 0.
  * (On return with 1 graph_lock is held.)
  */
-static inline int lookup_chain_cache(u64 chain_key, struct lock_class *class)
+static inline int lookup_chain_cache(struct task_struct *curr,
+                                     struct held_lock *hlock,
+                                     u64 chain_key)
 {
+        struct lock_class *class = hlock->class;
         struct list_head *hash_head = chainhashentry(chain_key);
         struct lock_chain *chain;
+        struct held_lock *hlock_curr, *hlock_next;
+        int i, j, n;
 
         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
                 return 0;
@@ -1517,6 +1529,26 @@ cache_hit:
         }
         chain = lock_chains + nr_lock_chains++;
         chain->chain_key = chain_key;
+        chain->irq_context = hlock->irq_context;
+        /* Find the first held_lock of current chain */
+        hlock_next = hlock;
+        for (i = curr->lockdep_depth - 1; i >= 0; i--) {
+                hlock_curr = curr->held_locks + i;
+                if (hlock_curr->irq_context != hlock_next->irq_context)
+                        break;
+                hlock_next = hlock;
+        }
+        i++;
+        chain->depth = curr->lockdep_depth + 1 - i;
+        n = atomic_add_return(chain->depth, &nr_chain_hlocks);
+        if (unlikely(n < MAX_LOCKDEP_CHAIN_HLOCKS)) {
+                chain->base = n - chain->depth;
+                for (j = 0; j < chain->depth - 1; j++, i++) {
+                        int lock_id = curr->held_locks[i].class - lock_classes;
+                        chain_hlocks[chain->base + j] = lock_id;
+                }
+                chain_hlocks[chain->base + j] = class - lock_classes;
+        }
         list_add_tail_rcu(&chain->entry, hash_head);
         debug_atomic_inc(&chain_lookup_misses);
         inc_chains();
@@ -1538,7 +1570,7 @@ static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
          * graph_lock for us)
          */
         if (!hlock->trylock && (hlock->check == 2) &&
-                        lookup_chain_cache(chain_key, hlock->class)) {
+            lookup_chain_cache(curr, hlock, chain_key)) {
                 /*
                  * Check whether last held lock:
                  *