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lockdep: Improve implementation of BFS

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1,replace %MAX_CIRCULAR_QUE_SIZE with &(MAX_CIRCULAR_QUE_SIZE-1)
since we define MAX_CIRCULAR_QUE_SIZE as power of 2;

2,use bitmap to mark if a lock is accessed in BFS in order to
clear it quickly, because we may search a graph many times.

Signed-off-by: Ming Lei <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Ming Lei 2009-07-16 15:44:29 +02:00 • committed by Peter Zijlstra
commit d588e46155
2 changed files with 39 additions and 19 deletions
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23
kernel/lockdep.c
View file

@ -42,7 +42,7 @@
#include <linux/hash.h>
#include <linux/ftrace.h>
#include <linux/stringify.h>
#include <linux/bitops.h>
#include <asm/sections.h>
#include "lockdep_internals.h"
@ -118,7 +118,7 @@ static inline int debug_locks_off_graph_unlock(void)
static int lockdep_initialized;
unsigned long nr_list_entries;
static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
/*
* All data structures here are protected by the global debug_lock.
@ -897,30 +897,38 @@ 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;
static int __search_shortest_path(struct lock_list *source_entry,
struct lock_class *target,
struct lock_list **target_entry,
int forward)
{
struct lock_list *entry;
struct list_head *head;
struct circular_queue *cq = &lock_cq;
int ret = 1;
__cq_init(cq);
mark_lock_accessed(source_entry, NULL);
if (source_entry->class == target) {
*target_entry = source_entry;
ret = 0;
goto exit;
}
if (forward)
head = &source_entry->class->locks_after;
else
head = &source_entry->class->locks_before;
if (list_empty(head))
goto exit;
__cq_init(cq);
__cq_enqueue(cq, (unsigned long)source_entry);
while (!__cq_empty(cq)) {
struct lock_list *lock;
struct list_head *head;
__cq_dequeue(cq, (unsigned long *)&lock);
@ -1040,6 +1048,7 @@ static noinline int print_circular_bug(void)
return 0;
this.class = hlock_class(check_source);
this.parent = NULL;
if (!save_trace(&this.trace))
return 0;
@ -1580,10 +1589,10 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
*/
check_source = next;
check_target = prev;
if (check_noncircular(hlock_class(next), 0) == 2)
return print_circular_bug();
if (!check_prev_add_irq(curr, prev, next))
return 0;