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Message-Id: <1214191255.23863.2.camel@caritas-dev.intel.com>
Date: Mon, 23 Jun 2008 11:20:54 +0800
From: "Huang, Ying" <ying.huang@...el.com>
To: Ingo Molnar <mingo@...e.hu>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH -v2] 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.
ChangeLog:
v2:
- Enclosing proc file system related code into CONFIG_PROVE_LOCKING.
- Fix nr_chain_hlocks update code.
Signed-off-by: Huang Ying <ying.huang@...el.com>
---
include/linux/lockdep.h | 3 +
kernel/lockdep.c | 44 +++++++++++++++++++-
kernel/lockdep_internals.h | 6 ++
kernel/lockdep_proc.c | 95 +++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 145 insertions(+), 3 deletions(-)
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -1463,7 +1463,14 @@ out_bug:
}
unsigned long nr_lock_chains;
-static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
+struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
+int 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
@@ -1471,10 +1478,15 @@ static struct lock_chain lock_chains[MAX
* 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, cn;
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return 0;
@@ -1522,6 +1534,32 @@ 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;
+ cn = nr_chain_hlocks;
+ while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
+ n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
+ if (n == cn)
+ break;
+ cn = n;
+ }
+ if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
+ chain->base = cn;
+ 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();
@@ -1543,7 +1581,7 @@ static int validate_chain(struct task_st
* 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:
*
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -182,6 +182,9 @@ struct lock_list {
* We record lock dependency chains, so that we can cache them:
*/
struct lock_chain {
+ u8 irq_context;
+ u8 depth;
+ u16 base;
struct list_head entry;
u64 chain_key;
};
--- a/kernel/lockdep_proc.c
+++ b/kernel/lockdep_proc.c
@@ -178,6 +178,95 @@ static const struct file_operations proc
.release = seq_release,
};
+#ifdef CONFIG_PROVE_LOCKING
+static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ struct lock_chain *chain;
+
+ (*pos)++;
+
+ if (v == SEQ_START_TOKEN)
+ chain = m->private;
+ else {
+ chain = v;
+
+ if (*pos < nr_lock_chains)
+ chain = lock_chains + *pos;
+ else
+ chain = NULL;
+ }
+
+ return chain;
+}
+
+static void *lc_start(struct seq_file *m, loff_t *pos)
+{
+ if (*pos == 0)
+ return SEQ_START_TOKEN;
+
+ if (*pos < nr_lock_chains)
+ return lock_chains + *pos;
+
+ return NULL;
+}
+
+static void lc_stop(struct seq_file *m, void *v)
+{
+}
+
+static int lc_show(struct seq_file *m, void *v)
+{
+ struct lock_chain *chain = v;
+ struct lock_class *class;
+ int i;
+
+ if (v == SEQ_START_TOKEN) {
+ seq_printf(m, "all lock chains:\n");
+ return 0;
+ }
+
+ seq_printf(m, "irq_context: %d\n", chain->irq_context);
+
+ for (i = 0; i < chain->depth; i++) {
+ class = lock_chain_get_class(chain, i);
+ seq_printf(m, "[%p] ", class->key);
+ print_name(m, class);
+ seq_puts(m, "\n");
+ }
+ seq_puts(m, "\n");
+
+ return 0;
+}
+
+static const struct seq_operations lockdep_chains_ops = {
+ .start = lc_start,
+ .next = lc_next,
+ .stop = lc_stop,
+ .show = lc_show,
+};
+
+static int lockdep_chains_open(struct inode *inode, struct file *file)
+{
+ int res = seq_open(file, &lockdep_chains_ops);
+ if (!res) {
+ struct seq_file *m = file->private_data;
+
+ if (nr_lock_chains)
+ m->private = lock_chains;
+ else
+ m->private = NULL;
+ }
+ return res;
+}
+
+static const struct file_operations proc_lockdep_chains_operations = {
+ .open = lockdep_chains_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+#endif /* CONFIG_PROVE_LOCKING */
+
static void lockdep_stats_debug_show(struct seq_file *m)
{
#ifdef CONFIG_DEBUG_LOCKDEP
@@ -294,6 +383,8 @@ static int lockdep_stats_show(struct seq
#ifdef CONFIG_PROVE_LOCKING
seq_printf(m, " dependency chains: %11lu [max: %lu]\n",
nr_lock_chains, MAX_LOCKDEP_CHAINS);
+ seq_printf(m, " dependency chain hlocks: %11d [max: %lu]\n",
+ nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS);
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
@@ -661,6 +752,10 @@ static const struct file_operations proc
static int __init lockdep_proc_init(void)
{
proc_create("lockdep", S_IRUSR, NULL, &proc_lockdep_operations);
+#ifdef CONFIG_PROVE_LOCKING
+ proc_create("lockdep_chains", S_IRUSR, NULL,
+ &proc_lockdep_chains_operations);
+#endif
proc_create("lockdep_stats", S_IRUSR, NULL,
&proc_lockdep_stats_operations);
--- a/kernel/lockdep_internals.h
+++ b/kernel/lockdep_internals.h
@@ -23,6 +23,8 @@
#define MAX_LOCKDEP_CHAINS_BITS 14
#define MAX_LOCKDEP_CHAINS (1UL << MAX_LOCKDEP_CHAINS_BITS)
+#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
+
/*
* Stack-trace: tightly packed array of stack backtrace
* addresses. Protected by the hash_lock.
@@ -30,15 +32,19 @@
#define MAX_STACK_TRACE_ENTRIES 262144UL
extern struct list_head all_lock_classes;
+extern struct lock_chain lock_chains[];
extern void
get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4);
extern const char * __get_key_name(struct lockdep_subclass_key *key, char *str);
+struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i);
+
extern unsigned long nr_lock_classes;
extern unsigned long nr_list_entries;
extern unsigned long nr_lock_chains;
+extern int nr_chain_hlocks;
extern unsigned long nr_stack_trace_entries;
extern unsigned int nr_hardirq_chains;
--
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