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Message-ID: <20080807205729.GB1747@debian>
Date: Fri, 8 Aug 2008 02:27:29 +0530
From: Rabin Vincent <rabin@....in>
To: Eric Sesterhenn <snakebyte@....de>
Cc: linux-kernel@...r.kernel.org, peterz@...radead.org,
mingo@...hat.com, ying.huang@...el.com
Subject: [PATCH] lockdep: handle chains involving classes defined in modules
/proc/lockdep_chains currently oopses after any module which creates and
uses a lock is unloaded. This is because one of the chains involves a
class which was defined in the module just unloaded.
The classes are already correctly taken care of using the
all_lock_classes which keeps track of all active lock classses. Add a
similar all_lock_chains list and use it for keeping track of chains.
Reported-by: Eric Sesterhenn <snakebyte@....de>
Signed-off-by: Rabin Vincent <rabin@....in>
---
include/linux/lockdep.h | 3 +-
kernel/lockdep.c | 53 ++++++++++++++++++++++++++++++++++++++-----
kernel/lockdep_internals.h | 2 +-
kernel/lockdep_proc.c | 17 ++++++++++----
4 files changed, 61 insertions(+), 14 deletions(-)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 2486eb4..735d06b 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -185,7 +185,8 @@ struct lock_chain {
u8 irq_context;
u8 depth;
u16 base;
- struct list_head entry;
+ struct list_head hash_entry;
+ struct list_head lock_entry;
u64 chain_key;
};
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index d38a643..1b3537b 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -253,6 +253,11 @@ LIST_HEAD(all_lock_classes);
static struct list_head classhash_table[CLASSHASH_SIZE];
/*
+ * We also keep a global list of all lock chains.
+ */
+LIST_HEAD(all_lock_chains);
+
+/*
* We put the lock dependency chains into a hash-table as well, to cache
* their existence:
*/
@@ -1462,7 +1467,7 @@ out_bug:
}
unsigned long nr_lock_chains;
-struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
+static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
int nr_chain_hlocks;
static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
@@ -1493,7 +1498,7 @@ static inline int lookup_chain_cache(struct task_struct *curr,
* We can walk it lock-free, because entries only get added
* to the hash:
*/
- list_for_each_entry(chain, hash_head, entry) {
+ list_for_each_entry(chain, hash_head, hash_entry) {
if (chain->chain_key == chain_key) {
cache_hit:
debug_atomic_inc(&chain_lookup_hits);
@@ -1517,7 +1522,7 @@ cache_hit:
/*
* We have to walk the chain again locked - to avoid duplicates:
*/
- list_for_each_entry(chain, hash_head, entry) {
+ list_for_each_entry(chain, hash_head, hash_entry) {
if (chain->chain_key == chain_key) {
graph_unlock();
goto cache_hit;
@@ -1559,7 +1564,8 @@ cache_hit:
}
chain_hlocks[chain->base + j] = class - lock_classes;
}
- list_add_tail_rcu(&chain->entry, hash_head);
+ list_add_tail_rcu(&chain->hash_entry, hash_head);
+ list_add_tail_rcu(&chain->lock_entry, &all_lock_chains);
debug_atomic_inc(&chain_lookup_misses);
inc_chains();
@@ -2967,6 +2973,8 @@ void lockdep_reset(void)
debug_locks = 1;
for (i = 0; i < CHAINHASH_SIZE; i++)
INIT_LIST_HEAD(chainhash_table + i);
+ for (i = 0; i < CLASSHASH_SIZE; i++)
+ INIT_LIST_HEAD(classhash_table + i);
raw_local_irq_restore(flags);
}
@@ -2990,6 +2998,15 @@ static void zap_class(struct lock_class *class)
}
+static void zap_chain(struct lock_chain *chain)
+{
+ /*
+ * Unhash the chain and remove it from the all_lock_chains list:
+ */
+ list_del_rcu(&chain->hash_entry);
+ list_del_rcu(&chain->lock_entry);
+}
+
static inline int within(const void *addr, void *start, unsigned long size)
{
return addr >= start && addr < start + size;
@@ -2997,23 +3014,45 @@ static inline int within(const void *addr, void *start, unsigned long size)
void lockdep_free_key_range(void *start, unsigned long size)
{
- struct lock_class *class, *next;
+ struct lock_class *class, *nextclass;
+ struct lock_chain *chain, *nextchain;
struct list_head *head;
unsigned long flags;
- int i;
+ int i, j;
int locked;
raw_local_irq_save(flags);
locked = graph_lock();
/*
+ * Unhash all chains that involve classes created by this module:
+ */
+ for (i = 0; i < CHAINHASH_SIZE; i++) {
+ head = chainhash_table + i;
+ if (list_empty(head))
+ continue;
+ list_for_each_entry_safe(chain, nextchain, head, hash_entry) {
+ for (j = 0; j < chain->depth; j++) {
+ class = lock_classes +
+ chain_hlocks[chain->base + j];
+
+ if (within(class->key, start, size) ||
+ within(class->name, start, size)) {
+ zap_chain(chain);
+ break;
+ }
+ }
+ }
+ }
+
+ /*
* Unhash all classes that were created by this module:
*/
for (i = 0; i < CLASSHASH_SIZE; i++) {
head = classhash_table + i;
if (list_empty(head))
continue;
- list_for_each_entry_safe(class, next, head, hash_entry) {
+ list_for_each_entry_safe(class, nextclass, head, hash_entry) {
if (within(class->key, start, size))
zap_class(class);
else if (within(class->name, start, size))
diff --git a/kernel/lockdep_internals.h b/kernel/lockdep_internals.h
index c3600a0..ebf2ecb 100644
--- a/kernel/lockdep_internals.h
+++ b/kernel/lockdep_internals.h
@@ -32,7 +32,7 @@
#define MAX_STACK_TRACE_ENTRIES 262144UL
extern struct list_head all_lock_classes;
-extern struct lock_chain lock_chains[];
+extern struct list_head all_lock_chains;
extern void
get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4);
diff --git a/kernel/lockdep_proc.c b/kernel/lockdep_proc.c
index 9b0e940..4f447fd 100644
--- a/kernel/lockdep_proc.c
+++ b/kernel/lockdep_proc.c
@@ -190,8 +190,9 @@ static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
else {
chain = v;
- if (*pos < nr_lock_chains)
- chain = lock_chains + *pos;
+ if (chain->lock_entry.next != &all_lock_chains)
+ chain = list_entry(chain->lock_entry.next,
+ struct lock_chain, lock_entry);
else
chain = NULL;
}
@@ -201,11 +202,16 @@ static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
static void *lc_start(struct seq_file *m, loff_t *pos)
{
+ struct lock_chain *chain;
+ loff_t i = 0;
+
if (*pos == 0)
return SEQ_START_TOKEN;
- if (*pos < nr_lock_chains)
- return lock_chains + *pos;
+ list_for_each_entry(chain, &all_lock_chains, lock_entry) {
+ if (++i == *pos)
+ return chain;
+ }
return NULL;
}
@@ -252,7 +258,8 @@ static int lockdep_chains_open(struct inode *inode, struct file *file)
struct seq_file *m = file->private_data;
if (nr_lock_chains)
- m->private = lock_chains;
+ m->private = list_entry(all_lock_chains.next,
+ struct lock_chain, lock_entry);
else
m->private = NULL;
}
--
1.5.6.3
--
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