[tip:locking/core] locking/lockdep: Add new check to lock_downgrade()
Commit-ID: 6419c4af777a773a45a1b1af735de0fcd9a7dcc7
Gitweb: http://git.kernel.org/tip/6419c4af777a773a45a1b1af735de0fcd9a7dcc7
Author: J. R. Okajima
AuthorDate: Fri, 3 Feb 2017 01:38:17 +0900
Committer: Ingo Molnar
CommitDate: Thu, 16 Mar 2017 09:57:07 +0100
locking/lockdep: Add new check to lock_downgrade()
Commit:
f8319483f57f ("locking/lockdep: Provide a type check for lock_is_held")
didn't fully cover rwsems as downgrade_write() was left out.
Introduce lock_downgrade() and use it to add new checks.
See-also: http://marc.info/?l=linux-kernel&m=148581164003149&w=2
Originally-written-by: Peter Zijlstra
Signed-off-by: J. R. Okajima
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link:
http://lkml.kernel.org/r/1486053497-9948-3-git-send-email-hooanon...@gmail.com
[ Rewrote the changelog. ]
Signed-off-by: Ingo Molnar
---
include/linux/lockdep.h | 3 +++
kernel/locking/lockdep.c | 55
kernel/locking/rwsem.c | 6 ++
3 files changed, 60 insertions(+), 4 deletions(-)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 1e327bb..fffe49f 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -361,6 +361,8 @@ static inline void lock_set_subclass(struct lockdep_map
*lock,
lock_set_class(lock, lock->name, lock->key, subclass, ip);
}
+extern void lock_downgrade(struct lockdep_map *lock, unsigned long ip);
+
extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
extern void lockdep_clear_current_reclaim_state(void);
extern void lockdep_trace_alloc(gfp_t mask);
@@ -411,6 +413,7 @@ static inline void lockdep_on(void)
# define lock_acquire(l, s, t, r, c, n, i) do { } while (0)
# define lock_release(l, n, i) do { } while (0)
+# define lock_downgrade(l, i) do { } while (0)
# define lock_set_class(l, n, k, s, i) do { } while (0)
# define lock_set_subclass(l, s, i)do { } while (0)
# define lockdep_set_current_reclaim_state(g) do { } while (0)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index da79548..b1a1cef 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3533,6 +3533,44 @@ __lock_set_class(struct lockdep_map *lock, const char
*name,
return 1;
}
+static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
+{
+ struct task_struct *curr = current;
+ struct held_lock *hlock;
+ unsigned int depth;
+ int i;
+
+ depth = curr->lockdep_depth;
+ /*
+* This function is about (re)setting the class of a held lock,
+* yet we're not actually holding any locks. Naughty user!
+*/
+ if (DEBUG_LOCKS_WARN_ON(!depth))
+ return 0;
+
+ hlock = find_held_lock(curr, lock, depth, &i);
+ if (!hlock)
+ return print_unlock_imbalance_bug(curr, lock, ip);
+
+ curr->lockdep_depth = i;
+ curr->curr_chain_key = hlock->prev_chain_key;
+
+ WARN(hlock->read, "downgrading a read lock");
+ hlock->read = 1;
+ hlock->acquire_ip = ip;
+
+ if (reacquire_held_locks(curr, depth, i))
+ return 0;
+
+ /*
+* I took it apart and put it back together again, except now I have
+* these 'spare' parts.. where shall I put them.
+*/
+ if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
+ return 0;
+ return 1;
+}
+
/*
* Remove the lock to the list of currently held locks - this gets
* called on mutex_unlock()/spin_unlock*() (or on a failed
@@ -3759,6 +3797,23 @@ void lock_set_class(struct lockdep_map *lock, const char
*name,
}
EXPORT_SYMBOL_GPL(lock_set_class);
+void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
+{
+ unsigned long flags;
+
+ if (unlikely(current->lockdep_recursion))
+ return;
+
+ raw_local_irq_save(flags);
+ current->lockdep_recursion = 1;
+ check_flags(flags);
+ if (__lock_downgrade(lock, ip))
+ check_chain_key(current);
+ current->lockdep_recursion = 0;
+ raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_downgrade);
+
/*
* We are not always called with irqs disabled - do that here,
* and also avoid lockdep recursion:
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 90a74cc..4d48b1c 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -124,10 +124,8 @@ EXPORT_SYMBOL(up_write);
*/
void downgrade_write(struct rw_semaphore *sem)
{
- /*
-* lockdep: a downgraded write will live on as a write
-* dependency.
-*/
+ lock_downgrade(&sem->dep_map, _RET_IP_);
+
rwsem_set_reader_owned(sem);
__downgrade_write(sem);
}
[tip:locking/core] locking/lockdep: Factor out the find_held_lock() helper function
Commit-ID: 41c2c5b86a5e1a691ddacfc03b631b87a0b19043
Gitweb: http://git.kernel.org/tip/41c2c5b86a5e1a691ddacfc03b631b87a0b19043
Author: J. R. Okajima
AuthorDate: Fri, 3 Feb 2017 01:38:15 +0900
Committer: Ingo Molnar
CommitDate: Thu, 16 Mar 2017 09:57:06 +0100
locking/lockdep: Factor out the find_held_lock() helper function
A simple consolidataion to factor out repeated patterns.
The behaviour should not change.
Signed-off-by: J. R. Okajima
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link:
http://lkml.kernel.org/r/1486053497-9948-1-git-send-email-hooanon...@gmail.com
Signed-off-by: Ingo Molnar
---
kernel/locking/lockdep.c | 114 ++-
1 file changed, 54 insertions(+), 60 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index a95e5d1..0d28b82 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3437,13 +3437,49 @@ static int match_held_lock(struct held_lock *hlock,
struct lockdep_map *lock)
return 0;
}
+/* @depth must not be zero */
+static struct held_lock *find_held_lock(struct task_struct *curr,
+ struct lockdep_map *lock,
+ unsigned int depth, int *idx)
+{
+ struct held_lock *ret, *hlock, *prev_hlock;
+ int i;
+
+ i = depth - 1;
+ hlock = curr->held_locks + i;
+ ret = hlock;
+ if (match_held_lock(hlock, lock))
+ goto out;
+
+ ret = NULL;
+ for (i--, prev_hlock = hlock--;
+i >= 0;
+i--, prev_hlock = hlock--) {
+ /*
+* We must not cross into another context:
+*/
+ if (prev_hlock->irq_context != hlock->irq_context) {
+ ret = NULL;
+ break;
+ }
+ if (match_held_lock(hlock, lock)) {
+ ret = hlock;
+ break;
+ }
+ }
+
+out:
+ *idx = i;
+ return ret;
+}
+
static int
__lock_set_class(struct lockdep_map *lock, const char *name,
struct lock_class_key *key, unsigned int subclass,
unsigned long ip)
{
struct task_struct *curr = current;
- struct held_lock *hlock, *prev_hlock;
+ struct held_lock *hlock;
struct lock_class *class;
unsigned int depth;
int i;
@@ -3456,21 +3492,10 @@ __lock_set_class(struct lockdep_map *lock, const char
*name,
if (DEBUG_LOCKS_WARN_ON(!depth))
return 0;
- prev_hlock = NULL;
- for (i = depth-1; i >= 0; i--) {
- hlock = curr->held_locks + i;
- /*
-* We must not cross into another context:
-*/
- if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
- break;
- if (match_held_lock(hlock, lock))
- goto found_it;
- prev_hlock = hlock;
- }
- return print_unlock_imbalance_bug(curr, lock, ip);
+ hlock = find_held_lock(curr, lock, depth, &i);
+ if (!hlock)
+ return print_unlock_imbalance_bug(curr, lock, ip);
-found_it:
lockdep_init_map(lock, name, key, 0);
class = register_lock_class(lock, subclass, 0);
hlock->class_idx = class - lock_classes + 1;
@@ -3508,7 +3533,7 @@ static int
__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
{
struct task_struct *curr = current;
- struct held_lock *hlock, *prev_hlock;
+ struct held_lock *hlock;
unsigned int depth;
int i;
@@ -3527,21 +3552,10 @@ __lock_release(struct lockdep_map *lock, int nested,
unsigned long ip)
* Check whether the lock exists in the current stack
* of held locks:
*/
- prev_hlock = NULL;
- for (i = depth-1; i >= 0; i--) {
- hlock = curr->held_locks + i;
- /*
-* We must not cross into another context:
-*/
- if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
- break;
- if (match_held_lock(hlock, lock))
- goto found_it;
- prev_hlock = hlock;
- }
- return print_unlock_imbalance_bug(curr, lock, ip);
+ hlock = find_held_lock(curr, lock, depth, &i);
+ if (!hlock)
+ return print_unlock_imbalance_bug(curr, lock, ip);
-found_it:
if (hlock->instance == lock)
lock_release_holdtime(hlock);
@@ -3903,7 +3917,7 @@ static void
__lock_contended(struct lockdep_map *lock, unsigned long ip)
{
struct task_struct *curr = current;
- struct held_lock *hlock, *prev_hlock;
+ struct held_lock *hlock;
struct loc
[tip:locking/core] locking/lockdep: Factor out the validate_held_lock() helper function
Commit-ID: e969970be033841d4c16b2e8ec8a3608347db861
Gitweb: http://git.kernel.org/tip/e969970be033841d4c16b2e8ec8a3608347db861
Author: J. R. Okajima
AuthorDate: Fri, 3 Feb 2017 01:38:16 +0900
Committer: Ingo Molnar
CommitDate: Thu, 16 Mar 2017 09:57:07 +0100
locking/lockdep: Factor out the validate_held_lock() helper function
Behaviour should not change.
Signed-off-by: J. R. Okajima
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link:
http://lkml.kernel.org/r/1486053497-9948-2-git-send-email-hooanon...@gmail.com
Signed-off-by: Ingo Molnar
---
kernel/locking/lockdep.c | 40 ++--
1 file changed, 22 insertions(+), 18 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 0d28b82..da79548 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3473,6 +3473,24 @@ out:
return ret;
}
+static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
+ int idx)
+{
+ struct held_lock *hlock;
+
+ for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
+ if (!__lock_acquire(hlock->instance,
+ hlock_class(hlock)->subclass,
+ hlock->trylock,
+ hlock->read, hlock->check,
+ hlock->hardirqs_off,
+ hlock->nest_lock, hlock->acquire_ip,
+ hlock->references, hlock->pin_count))
+ return 1;
+ }
+ return 0;
+}
+
static int
__lock_set_class(struct lockdep_map *lock, const char *name,
struct lock_class_key *key, unsigned int subclass,
@@ -3503,15 +3521,8 @@ __lock_set_class(struct lockdep_map *lock, const char
*name,
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
- for (; i < depth; i++) {
- hlock = curr->held_locks + i;
- if (!__lock_acquire(hlock->instance,
- hlock_class(hlock)->subclass, hlock->trylock,
- hlock->read, hlock->check, hlock->hardirqs_off,
- hlock->nest_lock, hlock->acquire_ip,
- hlock->references, hlock->pin_count))
- return 0;
- }
+ if (reacquire_held_locks(curr, depth, i))
+ return 0;
/*
* I took it apart and put it back together again, except now I have
@@ -3582,15 +3593,8 @@ __lock_release(struct lockdep_map *lock, int nested,
unsigned long ip)
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
- for (i++; i < depth; i++) {
- hlock = curr->held_locks + i;
- if (!__lock_acquire(hlock->instance,
- hlock_class(hlock)->subclass, hlock->trylock,
- hlock->read, hlock->check, hlock->hardirqs_off,
- hlock->nest_lock, hlock->acquire_ip,
- hlock->references, hlock->pin_count))
- return 0;
- }
+ if (reacquire_held_locks(curr, depth, i + 1))
+ return 0;
/*
* We had N bottles of beer on the wall, we drank one, but now
