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Subject[tip:core/locking] lockdep: BFS cleanup
Commit-ID:  af012961450949ea297b209e091bd1a3805b8a0a
Gitweb: http://git.kernel.org/tip/af012961450949ea297b209e091bd1a3805b8a0a
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Thu, 16 Jul 2009 15:44:29 +0200
Committer: Peter Zijlstra <a.p.zijlstra@chello.nl>
CommitDate: Fri, 24 Jul 2009 10:53:29 +0200

lockdep: BFS cleanup

Some cleanups of the lockdep code after the BFS series:

- Remove the last traces of the generation id
- Fixup comment style
- Move the bfs routines into lockdep.c
- Cleanup the bfs routines

[ tom.leiming@gmail.com: Fix crash ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1246201486-7308-11-git-send-email-tom.leiming@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
include/linux/lockdep.h | 7 +-
kernel/lockdep.c | 284 ++++++++++++++++++++++++++------------------
kernel/lockdep_internals.h | 97 +---------------
3 files changed, 175 insertions(+), 213 deletions(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 9ec026f..12aabfc 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -58,7 +58,6 @@ struct lock_class {

struct lockdep_subclass_key *key;
unsigned int subclass;
- unsigned int dep_gen_id;

/*
* IRQ/softirq usage tracking bits:
@@ -150,9 +149,9 @@ struct lock_list {
struct stack_trace trace;
int distance;

- /*The parent field is used to implement breadth-first search,and
- *the bit 0 is reused to indicate if the lock has been accessed
- *in BFS.
+ /*
+ * The parent field is used to implement breadth-first search, and the
+ * bit 0 is reused to indicate if the lock has been accessed in BFS.
*/
struct lock_list *parent;
};
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 744da62..1cedb00 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -43,6 +43,7 @@
#include <linux/ftrace.h>
#include <linux/stringify.h>
#include <linux/bitops.h>
+
#include <asm/sections.h>

#include "lockdep_internals.h"
@@ -118,7 +119,7 @@ static inline int debug_locks_off_graph_unlock(void)
static int lockdep_initialized;

unsigned long nr_list_entries;
-struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
+static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];

/*
* All data structures here are protected by the global debug_lock.
@@ -390,19 +391,6 @@ unsigned int nr_process_chains;
unsigned int max_lockdep_depth;
unsigned int max_recursion_depth;

-static unsigned int lockdep_dependency_gen_id;
-
-static bool lockdep_dependency_visit(struct lock_class *source,
- unsigned int depth)
-{
- if (!depth)
- lockdep_dependency_gen_id++;
- if (source->dep_gen_id == lockdep_dependency_gen_id)
- return true;
- source->dep_gen_id = lockdep_dependency_gen_id;
- return false;
-}
-
#ifdef CONFIG_DEBUG_LOCKDEP
/*
* We cannot printk in early bootup code. Not even early_printk()
@@ -551,88 +539,6 @@ static void lockdep_print_held_locks(struct task_struct *curr)
}
}

-static void print_lock_class_header(struct lock_class *class, int depth)
-{
- int bit;
-
- printk("%*s->", depth, "");
- print_lock_name(class);
- printk(" ops: %lu", class->ops);
- printk(" {\n");
-
- for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
- if (class->usage_mask & (1 << bit)) {
- int len = depth;
-
- len += printk("%*s %s", depth, "", usage_str[bit]);
- len += printk(" at:\n");
- print_stack_trace(class->usage_traces + bit, len);
- }
- }
- printk("%*s }\n", depth, "");
-
- printk("%*s ... key at: ",depth,"");
- print_ip_sym((unsigned long)class->key);
-}
-
-/*
- * printk the shortest lock dependencies from @start to @end in reverse order:
- */
-static void __used
-print_shortest_lock_dependencies(struct lock_list *leaf,
- struct lock_list *root)
-{
- struct lock_list *entry = leaf;
- int depth;
-
- /*compute depth from generated tree by BFS*/
- depth = get_lock_depth(leaf);
-
- do {
- print_lock_class_header(entry->class, depth);
- printk("%*s ... acquired at:\n", depth, "");
- print_stack_trace(&entry->trace, 2);
- printk("\n");
-
- if (depth == 0 && (entry != root)) {
- printk("lockdep:%s bad BFS generated tree\n", __func__);
- break;
- }
-
- entry = get_lock_parent(entry);
- depth--;
- } while (entry && (depth >= 0));
-
- return;
-}
-/*
- * printk all lock dependencies starting at <entry>:
- */
-static void __used
-print_lock_dependencies(struct lock_class *class, int depth)
-{
- struct lock_list *entry;
-
- if (lockdep_dependency_visit(class, depth))
- return;
-
- if (DEBUG_LOCKS_WARN_ON(depth >= 20))
- return;
-
- print_lock_class_header(class, depth);
-
- list_for_each_entry(entry, &class->locks_after, entry) {
- if (DEBUG_LOCKS_WARN_ON(!entry->class))
- return;
-
- print_lock_dependencies(entry->class, depth + 1);
-
- printk("%*s ... acquired at:\n",depth,"");
- print_stack_trace(&entry->trace, 2);
- printk("\n");
- }
-}
-
static void print_kernel_version(void)
{
printk("%s %.*s\n", init_utsname()->release,
@@ -927,14 +833,106 @@ static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
return 1;
}

-unsigned long bfs_accessed[BITS_TO_LONGS(MAX_LOCKDEP_ENTRIES)];
-static struct circular_queue lock_cq;
+/*For good efficiency of modular, we use power of 2*/
+#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
+#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
+
+/* The circular_queue and helpers is used to implement the
+ * breadth-first search(BFS)algorithem, by which we can build
+ * the shortest path from the next lock to be acquired to the
+ * previous held lock if there is a circular between them.
+ * */
+struct circular_queue {
+ unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
+ unsigned int front, rear;
+};
+
+static struct circular_queue lock_cq;
+static unsigned long bfs_accessed[BITS_TO_LONGS(MAX_LOCKDEP_ENTRIES)];
+
unsigned int max_bfs_queue_depth;
+
+static inline void __cq_init(struct circular_queue *cq)
+{
+ cq->front = cq->rear = 0;
+ bitmap_zero(bfs_accessed, MAX_LOCKDEP_ENTRIES);
+}
+
+static inline int __cq_empty(struct circular_queue *cq)
+{
+ return (cq->front == cq->rear);
+}
+
+static inline int __cq_full(struct circular_queue *cq)
+{
+ return ((cq->rear + 1) & CQ_MASK) == cq->front;
+}
+
+static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
+{
+ if (__cq_full(cq))
+ return -1;
+
+ cq->element[cq->rear] = elem;
+ cq->rear = (cq->rear + 1) & CQ_MASK;
+ return 0;
+}
+
+static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
+{
+ if (__cq_empty(cq))
+ return -1;
+
+ *elem = cq->element[cq->front];
+ cq->front = (cq->front + 1) & CQ_MASK;
+ return 0;
+}
+
+static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
+{
+ return (cq->rear - cq->front) & CQ_MASK;
+}
+
+static inline void mark_lock_accessed(struct lock_list *lock,
+ struct lock_list *parent)
+{
+ unsigned long nr;
+ nr = lock - list_entries;
+ WARN_ON(nr >= nr_list_entries);
+ lock->parent = parent;
+ set_bit(nr, bfs_accessed);
+}
+
+static inline unsigned long lock_accessed(struct lock_list *lock)
+{
+ unsigned long nr;
+ nr = lock - list_entries;
+ WARN_ON(nr >= nr_list_entries);
+ return test_bit(nr, bfs_accessed);
+}
+
+static inline struct lock_list *get_lock_parent(struct lock_list *child)
+{
+ return child->parent;
+}
+
+static inline int get_lock_depth(struct lock_list *child)
+{
+ int depth = 0;
+ struct lock_list *parent;
+
+ while ((parent = get_lock_parent(child))) {
+ child = parent;
+ depth++;
+ }
+ return depth;
+}
+
static int __bfs(struct lock_list *source_entry,
- void *data,
- int (*match)(struct lock_list *entry, void *data),
- struct lock_list **target_entry,
- int forward)
+ void *data,
+ int (*match)(struct lock_list *entry, void *data),
+ struct lock_list **target_entry,
+ int forward)
{
struct lock_list *entry;
struct list_head *head;
@@ -1202,14 +1200,6 @@ check_noncircular(struct lock_list *root, struct lock_class *target,
* without creating any illegal irq-safe -> irq-unsafe lock dependency.
*/

-
-#define BFS_PROCESS_RET(ret) do { \
- if (ret < 0) \
- return print_bfs_bug(ret); \
- if (ret == 1) \
- return 1; \
- } while (0)
-
static inline int usage_match(struct lock_list *entry, void *bit)
{
return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
@@ -1263,6 +1253,60 @@ find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
return result;
}

+static void print_lock_class_header(struct lock_class *class, int depth)
+{
+ int bit;
+
+ printk("%*s->", depth, "");
+ print_lock_name(class);
+ printk(" ops: %lu", class->ops);
+ printk(" {\n");
+
+ for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
+ if (class->usage_mask & (1 << bit)) {
+ int len = depth;
+
+ len += printk("%*s %s", depth, "", usage_str[bit]);
+ len += printk(" at:\n");
+ print_stack_trace(class->usage_traces + bit, len);
+ }
+ }
+ printk("%*s }\n", depth, "");
+
+ printk("%*s ... key at: ",depth,"");
+ print_ip_sym((unsigned long)class->key);
+}
+
+/*
+ * printk the shortest lock dependencies from @start to @end in reverse order:
+ */
+static void __used
+print_shortest_lock_dependencies(struct lock_list *leaf,
+ struct lock_list *root)
+{
+ struct lock_list *entry = leaf;
+ int depth;
+
+ /*compute depth from generated tree by BFS*/
+ depth = get_lock_depth(leaf);
+
+ do {
+ print_lock_class_header(entry->class, depth);
+ printk("%*s ... acquired at:\n", depth, "");
+ print_stack_trace(&entry->trace, 2);
+ printk("\n");
+
+ if (depth == 0 && (entry != root)) {
+ printk("lockdep:%s bad BFS generated tree\n", __func__);
+ break;
+ }
+
+ entry = get_lock_parent(entry);
+ depth--;
+ } while (entry && (depth >= 0));
+
+ return;
+}

static int
print_bad_irq_dependency(struct task_struct *curr,
@@ -1349,12 +1393,18 @@ check_usage(struct task_struct *curr, struct held_lock *prev,

this.class = hlock_class(prev);
ret = find_usage_backwards(&this, bit_backwards, &target_entry);
- BFS_PROCESS_RET(ret);
+ if (ret < 0)
+ return print_bfs_bug(ret);
+ if (ret == 1)
+ return ret;

that.parent = NULL;
that.class = hlock_class(next);
ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
- BFS_PROCESS_RET(ret);
+ if (ret < 0)
+ return print_bfs_bug(ret);
+ if (ret == 1)
+ return ret;

return print_bad_irq_dependency(curr, &this, &that,
target_entry, target_entry1,
@@ -2038,7 +2088,10 @@ check_usage_forwards(struct task_struct *curr, struct held_lock *this,
root.parent = NULL;
root.class = hlock_class(this);
ret = find_usage_forwards(&root, bit, &target_entry);
- BFS_PROCESS_RET(ret);
+ if (ret < 0)
+ return print_bfs_bug(ret);
+ if (ret == 1)
+ return ret;

return print_irq_inversion_bug(curr, &root, target_entry,
this, 1, irqclass);
@@ -2059,7 +2112,10 @@ check_usage_backwards(struct task_struct *curr, struct held_lock *this,
root.parent = NULL;
root.class = hlock_class(this);
ret = find_usage_backwards(&root, bit, &target_entry);
- BFS_PROCESS_RET(ret);
+ if (ret < 0)
+ return print_bfs_bug(ret);
+ if (ret == 1)
+ return ret;

return print_irq_inversion_bug(curr, &root, target_entry,
this, 1, irqclass);
diff --git a/kernel/lockdep_internals.h b/kernel/lockdep_internals.h
index 6baa880..a2ee95a 100644
--- a/kernel/lockdep_internals.h
+++ b/kernel/lockdep_internals.h
@@ -91,6 +91,8 @@ extern unsigned int nr_process_chains;
extern unsigned int max_lockdep_depth;
extern unsigned int max_recursion_depth;

+extern unsigned int max_bfs_queue_depth;
+
#ifdef CONFIG_PROVE_LOCKING
extern unsigned long lockdep_count_forward_deps(struct lock_class *);
extern unsigned long lockdep_count_backward_deps(struct lock_class *);
@@ -136,98 +138,3 @@ extern atomic_t nr_find_usage_backwards_recursions;
# define debug_atomic_dec(ptr) do { } while (0)
# define debug_atomic_read(ptr) 0
#endif
-
-
-extern unsigned int max_bfs_queue_depth;
-extern unsigned long nr_list_entries;
-extern struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
-extern unsigned long bfs_accessed[];
-
-/*For good efficiency of modular, we use power of 2*/
-#define MAX_CIRCULAR_QUE_SIZE 4096UL
-
-/* The circular_queue and helpers is used to implement the
- * breadth-first search(BFS)algorithem, by which we can build
- * the shortest path from the next lock to be acquired to the
- * previous held lock if there is a circular between them.
- * */
-struct circular_queue{
- unsigned long element[MAX_CIRCULAR_QUE_SIZE];
- unsigned int front, rear;
-};
-
-static inline void __cq_init(struct circular_queue *cq)
-{
- cq->front = cq->rear = 0;
- bitmap_zero(bfs_accessed, MAX_LOCKDEP_ENTRIES);
-}
-
-static inline int __cq_empty(struct circular_queue *cq)
-{
- return (cq->front == cq->rear);
-}
-
-static inline int __cq_full(struct circular_queue *cq)
-{
- return ((cq->rear + 1)&(MAX_CIRCULAR_QUE_SIZE-1)) == cq->front;
-}
-
-static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
-{
- if (__cq_full(cq))
- return -1;
-
- cq->element[cq->rear] = elem;
- cq->rear = (cq->rear + 1)&(MAX_CIRCULAR_QUE_SIZE-1);
- return 0;
-}
-
-static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
-{
- if (__cq_empty(cq))
- return -1;
-
- *elem = cq->element[cq->front];
- cq->front = (cq->front + 1)&(MAX_CIRCULAR_QUE_SIZE-1);
- return 0;
-}
-
-static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
-{
- return (cq->rear - cq->front)&(MAX_CIRCULAR_QUE_SIZE-1);
-}
-
-static inline void mark_lock_accessed(struct lock_list *lock,
- struct lock_list *parent)
-{
- unsigned long nr;
- nr = lock - list_entries;
- WARN_ON(nr >= nr_list_entries);
- lock->parent = parent;
- set_bit(nr, bfs_accessed);
-}
-
-static inline unsigned long lock_accessed(struct lock_list *lock)
-{
- unsigned long nr;
- nr = lock - list_entries;
- WARN_ON(nr >= nr_list_entries);
- return test_bit(nr, bfs_accessed);
-}
-
-static inline struct lock_list *get_lock_parent(struct lock_list *child)
-{
- return child->parent;
-}
-
-static inline int get_lock_depth(struct lock_list *child)
-{
- int depth = 0;
- struct lock_list *parent;
-
- while ((parent = get_lock_parent(child))) {
- child = parent;
- depth++;
- }
- return depth;
-}

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