5 files changed, 49 insertions, 17 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index d62e3cdab357..5e3407d997b2 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -499,6 +499,18 @@ config PROVE_LOCKING
 
          For more details, see Documentation/lockdep-design.txt.
 
+config PROVE_RCU
+        bool "RCU debugging: prove RCU correctness"
+        depends on PROVE_LOCKING
+        default n
+        help
+         This feature enables lockdep extensions that check for correct
+         use of RCU APIs.  This is currently under development.  Say Y
+         if you want to debug RCU usage or help work on the PROVE_RCU
+         feature.
+
+         Say N if you are unsure.
+
 config LOCKDEP
         bool
         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
@@ -765,10 +777,22 @@ config RCU_CPU_STALL_DETECTOR
           CPUs are delaying the current grace period, but only when
           the grace period extends for excessive time periods.
 
-          Say Y if you want RCU to perform such checks.
+          Say N if you want to disable such checks.
+
+          Say Y if you are unsure.
+
+config RCU_CPU_STALL_VERBOSE
+        bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
+        depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
+        default n
+        help
+          This option causes RCU to printk detailed per-task information
+          for any tasks that are stalling the current RCU grace period.
 
           Say N if you are unsure.
 
+          Say Y if you want to enable such checks.
+
 config KPROBES_SANITY_TEST
         bool "Kprobes sanity tests"
         depends on DEBUG_KERNEL
diff --git a/lib/debug_locks.c b/lib/debug_locks.c
index bc3b11731b9c..5bf0020b9248 100644
--- a/lib/debug_locks.c
+++ b/lib/debug_locks.c
@@ -23,6 +23,7 @@
  * shut up after that.
  */
 int debug_locks = 1;
+EXPORT_SYMBOL_GPL(debug_locks);
 
 /*
  * The locking-testsuite uses <debug_locks_silent> to get a
diff --git a/lib/hweight.c b/lib/hweight.c
index 389424ecb129..63ee4eb1228d 100644
--- a/lib/hweight.c
+++ b/lib/hweight.c
@@ -11,11 +11,18 @@
 
 unsigned int hweight32(unsigned int w)
 {
+#ifdef ARCH_HAS_FAST_MULTIPLIER
+        w -= (w >> 1) & 0x55555555;
+        w =  (w & 0x33333333) + ((w >> 2) & 0x33333333);
+        w =  (w + (w >> 4)) & 0x0f0f0f0f;
+        return (w * 0x01010101) >> 24;
+#else
         unsigned int res = w - ((w >> 1) & 0x55555555);
         res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
         res = (res + (res >> 4)) & 0x0F0F0F0F;
         res = res + (res >> 8);
         return (res + (res >> 16)) & 0x000000FF;
+#endif
 }
 EXPORT_SYMBOL(hweight32);
 
diff --git a/lib/idr.c b/lib/idr.c
index 0dc782216d4b..2eb1dca03681 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -504,7 +504,7 @@ void *idr_find(struct idr *idp, int id)
         int n;
         struct idr_layer *p;
 
-        p = rcu_dereference(idp->top);
+        p = rcu_dereference_raw(idp->top);
         if (!p)
                 return NULL;
         n = (p->layer+1) * IDR_BITS;
@@ -519,7 +519,7 @@ void *idr_find(struct idr *idp, int id)
         while (n > 0 && p) {
                 n -= IDR_BITS;
                 BUG_ON(n != p->layer*IDR_BITS);
-                p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]);
+                p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
         }
         return((void *)p);
 }
@@ -552,7 +552,7 @@ int idr_for_each(struct idr *idp,
         struct idr_layer **paa = &pa[0];
 
         n = idp->layers * IDR_BITS;
-        p = rcu_dereference(idp->top);
+        p = rcu_dereference_raw(idp->top);
         max = 1 << n;
 
         id = 0;
@@ -560,7 +560,7 @@ int idr_for_each(struct idr *idp,
                 while (n > 0 && p) {
                         n -= IDR_BITS;
                         *paa++ = p;
-                        p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]);
+                        p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
                 }
 
                 if (p) {
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 92cdd9936e3d..6b9670d6bbf9 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -364,7 +364,7 @@ static void *radix_tree_lookup_element(struct radix_tree_root *root,
         unsigned int height, shift;
         struct radix_tree_node *node, **slot;
 
-        node = rcu_dereference(root->rnode);
+        node = rcu_dereference_raw(root->rnode);
         if (node == NULL)
                 return NULL;
 
@@ -384,7 +384,7 @@ static void *radix_tree_lookup_element(struct radix_tree_root *root,
         do {
                 slot = (struct radix_tree_node **)
                         (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
-                node = rcu_dereference(*slot);
+                node = rcu_dereference_raw(*slot);
                 if (node == NULL)
                         return NULL;
 
@@ -568,7 +568,7 @@ int radix_tree_tag_get(struct radix_tree_root *root,
         if (!root_tag_get(root, tag))
                 return 0;
 
-        node = rcu_dereference(root->rnode);
+        node = rcu_dereference_raw(root->rnode);
         if (node == NULL)
                 return 0;
 
@@ -602,7 +602,7 @@ int radix_tree_tag_get(struct radix_tree_root *root,
                         BUG_ON(ret && saw_unset_tag);
                         return !!ret;
                 }
-                node = rcu_dereference(node->slots[offset]);
+                node = rcu_dereference_raw(node->slots[offset]);
                 shift -= RADIX_TREE_MAP_SHIFT;
                 height--;
         }
@@ -711,7 +711,7 @@ __lookup(struct radix_tree_node *slot, void ***results, unsigned long index,
                 }
 
                 shift -= RADIX_TREE_MAP_SHIFT;
-                slot = rcu_dereference(slot->slots[i]);
+                slot = rcu_dereference_raw(slot->slots[i]);
                 if (slot == NULL)
                         goto out;
         }
@@ -758,7 +758,7 @@ radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
         unsigned long cur_index = first_index;
         unsigned int ret;
 
-        node = rcu_dereference(root->rnode);
+        node = rcu_dereference_raw(root->rnode);
         if (!node)
                 return 0;
 
@@ -787,7 +787,7 @@ radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
                         slot = *(((void ***)results)[ret + i]);
                         if (!slot)
                                 continue;
-                        results[ret + nr_found] = rcu_dereference(slot);
+                        results[ret + nr_found] = rcu_dereference_raw(slot);
                         nr_found++;
                 }
                 ret += nr_found;
@@ -826,7 +826,7 @@ radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results,
         unsigned long cur_index = first_index;
         unsigned int ret;
 
-        node = rcu_dereference(root->rnode);
+        node = rcu_dereference_raw(root->rnode);
         if (!node)
                 return 0;
 
@@ -915,7 +915,7 @@ __lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index,
                         }
                 }
                 shift -= RADIX_TREE_MAP_SHIFT;
-                slot = rcu_dereference(slot->slots[i]);
+                slot = rcu_dereference_raw(slot->slots[i]);
                 if (slot == NULL)
                         break;
         }
@@ -951,7 +951,7 @@ radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
         if (!root_tag_get(root, tag))
                 return 0;
 
-        node = rcu_dereference(root->rnode);
+        node = rcu_dereference_raw(root->rnode);
         if (!node)
                 return 0;
 
@@ -980,7 +980,7 @@ radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
                         slot = *(((void ***)results)[ret + i]);
                         if (!slot)
                                 continue;
-                        results[ret + nr_found] = rcu_dereference(slot);
+                        results[ret + nr_found] = rcu_dereference_raw(slot);
                         nr_found++;
                 }
                 ret += nr_found;
@@ -1020,7 +1020,7 @@ radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
         if (!root_tag_get(root, tag))
                 return 0;
 
-        node = rcu_dereference(root->rnode);
+        node = rcu_dereference_raw(root->rnode);
         if (!node)
                 return 0;