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locking/lockdep: Convert hash tables to hlists 

Mike said:

: CONFIG_UBSAN_ALIGNMENT breaks x86-64 kernel with lockdep enabled, i.e.
: kernel with CONFIG_UBSAN_ALIGNMENT=y fails to load without even any error
: message.
:
: The problem is that ubsan callbacks use spinlocks and might be called
: before lockdep is initialized.  Particularly this line in the
: reserve_ebda_region function causes problem:
:
: lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
:
: If i put lockdep_init() before reserve_ebda_region call in
: x86_64_start_reservations kernel loads well.

Fix this ordering issue permanently: change lockdep so that it uses hlists
for the hash tables.  Unlike a list_head, an hlist_head is in its
initialized state when it is all-zeroes, so lockdep is ready for operation
immediately upon boot - lockdep_init() need not have run.

The patch will also save some memory.

Probably lockdep_init() and lockdep_initialized can be done away with now.

Suggested-by: Mike Krinkin <krinkin.m.u@gmail.com>
Reported-by: Mike Krinkin <krinkin.m.u@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: mm-commits@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andrew Morton 2016-02-03 13:44:12 -08:00 committed by Ingo Molnar
parent 3aa6b46c6d
commit a63f38cc4c
2 changed files with 21 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/lockdep.h
View File

@ -66,7 +66,7 @@ struct lock_class {
/* /*
* class-hash: * class-hash:
*/ */
struct list_head hash_entry; struct hlist_node hash_entry;
/* /*
* global list of all lock-classes: * global list of all lock-classes:
@ -199,7 +199,7 @@ struct lock_chain {
u8 irq_context; u8 irq_context;
u8 depth; u8 depth;
u16 base; u16 base;
struct list_head entry; struct hlist_node entry;
u64 chain_key; u64 chain_key;
}; };

42
kernel/locking/lockdep.c
View File

@ -292,7 +292,7 @@ LIST_HEAD(all_lock_classes);
#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS) #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
#define classhashentry(key) (classhash_table + __classhashfn((key))) #define classhashentry(key) (classhash_table + __classhashfn((key)))
static struct list_head classhash_table[CLASSHASH_SIZE]; static struct hlist_head classhash_table[CLASSHASH_SIZE];
/* /*
* We put the lock dependency chains into a hash-table as well, to cache * We put the lock dependency chains into a hash-table as well, to cache
@ -303,7 +303,7 @@ static struct list_head classhash_table[CLASSHASH_SIZE];
#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS) #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
static struct list_head chainhash_table[CHAINHASH_SIZE]; static struct hlist_head chainhash_table[CHAINHASH_SIZE];
/* /*
* The hash key of the lock dependency chains is a hash itself too: * The hash key of the lock dependency chains is a hash itself too:
@ -666,7 +666,7 @@ static inline struct lock_class *
look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
{ {
struct lockdep_subclass_key *key; struct lockdep_subclass_key *key;
struct list_head *hash_head; struct hlist_head *hash_head;
struct lock_class *class; struct lock_class *class;
#ifdef CONFIG_DEBUG_LOCKDEP #ifdef CONFIG_DEBUG_LOCKDEP
@ -719,7 +719,7 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return NULL; return NULL;
list_for_each_entry_rcu(class, hash_head, hash_entry) { hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
if (class->key == key) { if (class->key == key) {
/* /*
* Huh! same key, different name? Did someone trample * Huh! same key, different name? Did someone trample
@ -742,7 +742,7 @@ static inline struct lock_class *
register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
{ {
struct lockdep_subclass_key *key; struct lockdep_subclass_key *key;
struct list_head *hash_head; struct hlist_head *hash_head;
struct lock_class *class; struct lock_class *class;
DEBUG_LOCKS_WARN_ON(!irqs_disabled()); DEBUG_LOCKS_WARN_ON(!irqs_disabled());
@ -774,7 +774,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
* We have to do the hash-walk again, to avoid races * We have to do the hash-walk again, to avoid races
* with another CPU: * with another CPU:
*/ */
list_for_each_entry_rcu(class, hash_head, hash_entry) { hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
if (class->key == key) if (class->key == key)
goto out_unlock_set; goto out_unlock_set;
} }
@ -805,7 +805,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
* We use RCU's safe list-add method to make * We use RCU's safe list-add method to make
* parallel walking of the hash-list safe: * parallel walking of the hash-list safe:
*/ */
list_add_tail_rcu(&class->hash_entry, hash_head); hlist_add_head_rcu(&class->hash_entry, hash_head);
/* /*
* Add it to the global list of classes: * Add it to the global list of classes:
*/ */
@ -2021,7 +2021,7 @@ static inline int lookup_chain_cache(struct task_struct *curr,
u64 chain_key) u64 chain_key)
{ {
struct lock_class *class = hlock_class(hlock); struct lock_class *class = hlock_class(hlock);
struct list_head *hash_head = chainhashentry(chain_key); struct hlist_head *hash_head = chainhashentry(chain_key);
struct lock_chain *chain; struct lock_chain *chain;
struct held_lock *hlock_curr; struct held_lock *hlock_curr;
int i, j; int i, j;
@ -2037,7 +2037,7 @@ static inline int lookup_chain_cache(struct task_struct *curr,
* We can walk it lock-free, because entries only get added * We can walk it lock-free, because entries only get added
* to the hash: * to the hash:
*/ */
list_for_each_entry_rcu(chain, hash_head, entry) { hlist_for_each_entry_rcu(chain, hash_head, entry) {
if (chain->chain_key == chain_key) { if (chain->chain_key == chain_key) {
cache_hit: cache_hit:
debug_atomic_inc(chain_lookup_hits); debug_atomic_inc(chain_lookup_hits);
@ -2061,7 +2061,7 @@ cache_hit:
/* /*
* We have to walk the chain again locked - to avoid duplicates: * We have to walk the chain again locked - to avoid duplicates:
*/ */
list_for_each_entry(chain, hash_head, entry) { hlist_for_each_entry(chain, hash_head, entry) {
if (chain->chain_key == chain_key) { if (chain->chain_key == chain_key) {
graph_unlock(); graph_unlock();
goto cache_hit; goto cache_hit;
@ -2095,7 +2095,7 @@ cache_hit:
} }
chain_hlocks[chain->base + j] = class - lock_classes; chain_hlocks[chain->base + j] = class - lock_classes;
} }
list_add_tail_rcu(&chain->entry, hash_head); hlist_add_head_rcu(&chain->entry, hash_head);
debug_atomic_inc(chain_lookup_misses); debug_atomic_inc(chain_lookup_misses);
inc_chains(); inc_chains();
@ -3879,7 +3879,7 @@ void lockdep_reset(void)
nr_process_chains = 0; nr_process_chains = 0;
debug_locks = 1; debug_locks = 1;
for (i = 0; i < CHAINHASH_SIZE; i++) for (i = 0; i < CHAINHASH_SIZE; i++)
INIT_LIST_HEAD(chainhash_table + i); INIT_HLIST_HEAD(chainhash_table + i);
raw_local_irq_restore(flags); raw_local_irq_restore(flags);
} }
@ -3898,7 +3898,7 @@ static void zap_class(struct lock_class *class)
/* /*
* Unhash the class and remove it from the all_lock_classes list: * Unhash the class and remove it from the all_lock_classes list:
*/ */
list_del_rcu(&class->hash_entry); hlist_del_rcu(&class->hash_entry);
list_del_rcu(&class->lock_entry); list_del_rcu(&class->lock_entry);
RCU_INIT_POINTER(class->key, NULL); RCU_INIT_POINTER(class->key, NULL);
@ -3921,7 +3921,7 @@ static inline int within(const void *addr, void *start, unsigned long size)
void lockdep_free_key_range(void *start, unsigned long size) void lockdep_free_key_range(void *start, unsigned long size)
{ {
struct lock_class *class; struct lock_class *class;
struct list_head *head; struct hlist_head *head;
unsigned long flags; unsigned long flags;
int i; int i;
int locked; int locked;
@ -3934,9 +3934,7 @@ void lockdep_free_key_range(void *start, unsigned long size)
*/ */
for (i = 0; i < CLASSHASH_SIZE; i++) { for (i = 0; i < CLASSHASH_SIZE; i++) {
head = classhash_table + i; head = classhash_table + i;
if (list_empty(head)) hlist_for_each_entry_rcu(class, head, hash_entry) {
continue;
list_for_each_entry_rcu(class, head, hash_entry) {
if (within(class->key, start, size)) if (within(class->key, start, size))
zap_class(class); zap_class(class);
else if (within(class->name, start, size)) else if (within(class->name, start, size))
@ -3966,7 +3964,7 @@ void lockdep_free_key_range(void *start, unsigned long size)
void lockdep_reset_lock(struct lockdep_map *lock) void lockdep_reset_lock(struct lockdep_map *lock)
{ {
struct lock_class *class; struct lock_class *class;
struct list_head *head; struct hlist_head *head;
unsigned long flags; unsigned long flags;
int i, j; int i, j;
int locked; int locked;
@ -3991,9 +3989,7 @@ void lockdep_reset_lock(struct lockdep_map *lock)
locked = graph_lock(); locked = graph_lock();
for (i = 0; i < CLASSHASH_SIZE; i++) { for (i = 0; i < CLASSHASH_SIZE; i++) {
head = classhash_table + i; head = classhash_table + i;
if (list_empty(head)) hlist_for_each_entry_rcu(class, head, hash_entry) {
continue;
list_for_each_entry_rcu(class, head, hash_entry) {
int match = 0; int match = 0;
for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++) for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
@ -4031,10 +4027,10 @@ void lockdep_init(void)
return; return;
for (i = 0; i < CLASSHASH_SIZE; i++) for (i = 0; i < CLASSHASH_SIZE; i++)
INIT_LIST_HEAD(classhash_table + i); INIT_HLIST_HEAD(classhash_table + i);
for (i = 0; i < CHAINHASH_SIZE; i++) for (i = 0; i < CHAINHASH_SIZE; i++)
INIT_LIST_HEAD(chainhash_table + i); INIT_HLIST_HEAD(chainhash_table + i);
lockdep_initialized = 1; lockdep_initialized = 1;
} }