Commit 6419c4af authored by J. R. Okajima's avatar J. R. Okajima Committed by Ingo Molnar

locking/lockdep: Add new check to lock_downgrade()

Commit:

  f8319483 ("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=2Originally-written-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarJ. R. Okajima <hooanon05g@gmail.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
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>
Link: http://lkml.kernel.org/r/1486053497-9948-3-git-send-email-hooanon05g@gmail.com
[ Rewrote the changelog. ]
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e969970b
...@@ -361,6 +361,8 @@ static inline void lock_set_subclass(struct lockdep_map *lock, ...@@ -361,6 +361,8 @@ static inline void lock_set_subclass(struct lockdep_map *lock,
lock_set_class(lock, lock->name, lock->key, subclass, ip); 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_set_current_reclaim_state(gfp_t gfp_mask);
extern void lockdep_clear_current_reclaim_state(void); extern void lockdep_clear_current_reclaim_state(void);
extern void lockdep_trace_alloc(gfp_t mask); extern void lockdep_trace_alloc(gfp_t mask);
...@@ -411,6 +413,7 @@ static inline void lockdep_on(void) ...@@ -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_acquire(l, s, t, r, c, n, i) do { } while (0)
# define lock_release(l, 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_class(l, n, k, s, i) do { } while (0)
# define lock_set_subclass(l, 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) # define lockdep_set_current_reclaim_state(g) do { } while (0)
......
...@@ -3533,6 +3533,44 @@ __lock_set_class(struct lockdep_map *lock, const char *name, ...@@ -3533,6 +3533,44 @@ __lock_set_class(struct lockdep_map *lock, const char *name,
return 1; 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 * Remove the lock to the list of currently held locks - this gets
* called on mutex_unlock()/spin_unlock*() (or on a failed * 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, ...@@ -3759,6 +3797,23 @@ void lock_set_class(struct lockdep_map *lock, const char *name,
} }
EXPORT_SYMBOL_GPL(lock_set_class); 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, * We are not always called with irqs disabled - do that here,
* and also avoid lockdep recursion: * and also avoid lockdep recursion:
......
...@@ -124,10 +124,8 @@ EXPORT_SYMBOL(up_write); ...@@ -124,10 +124,8 @@ EXPORT_SYMBOL(up_write);
*/ */
void downgrade_write(struct rw_semaphore *sem) void downgrade_write(struct rw_semaphore *sem)
{ {
/* lock_downgrade(&sem->dep_map, _RET_IP_);
* lockdep: a downgraded write will live on as a write
* dependency.
*/
rwsem_set_reader_owned(sem); rwsem_set_reader_owned(sem);
__downgrade_write(sem); __downgrade_write(sem);
} }
......
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