On Mon, Sep 05, 2016 at 05:12:44PM +0200, Christoph Hellwig wrote:
> Peter, this is the fixed up patch. Can you write a proper changelog
> and add your signoff?
Yes, sorry for the delay.
Did you get the workqueue thing sorted, where you rely on another task
holding the lock for you?
I simplified the implementation a little, since I noticed pushing the
@read argument all the way down to match_held_lock() didn't really make
all that much sense and caused a lot of churn.
I also added CONFIG_LOCKDEP=n stubs for the new lockdep_assert_held*()
macros (which you don't use :-).
Feel free to push this through the XFS tree where you add its first use.
---
Subject: locking/lockdep: Provide a type check for lock_is_held
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Mon, 5 Sep 2016 17:12:44 +0200
Christoph requested lockdep_assert_held() variants that distinguish
between held-for-read or held-for-write.
Provide:
int lock_is_held_type(struct lockdep_map *lock, int read)
which takes the same argument as lock_acquire(.read) and matches it to
the held_lock instance.
Use of this function should be gated by the debug_locks variable. When
that is 0 the return value of the lock_is_held_type() function is
undefined. This is done to allow both negative and positive tests for
holding locks.
By default we provide (positive)
lockdep_assert_held{,_exclusive,_read}() macros.
Requested-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
include/linux/lockdep.h | 23 +++++++++++++++++++++--
kernel/locking/lockdep.c | 20 ++++++++++++--------
2 files changed, 33 insertions(+), 10 deletions(-)
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -338,9 +338,18 @@ extern void lock_acquire(struct lockdep_
extern void lock_release(struct lockdep_map *lock, int nested,
unsigned long ip);
-#define lockdep_is_held(lock) lock_is_held(&(lock)->dep_map)
+/*
+ * Same "read" as for lock_acquire(), except -1 means any.
+ */
+extern int lock_is_held_type(struct lockdep_map *lock, int read);
+
+static inline int lock_is_held(struct lockdep_map *lock)
+{
+ return lock_is_held_type(lock, -1);
+}
-extern int lock_is_held(struct lockdep_map *lock);
+#define lockdep_is_held(lock) lock_is_held(&(lock)->dep_map)
+#define lockdep_is_held_type(lock, r) lock_is_held_type(&(lock)->dep_map, (r))
extern void lock_set_class(struct lockdep_map *lock, const char *name,
struct lock_class_key *key, unsigned int subclass,
@@ -372,6 +381,14 @@ extern void lock_unpin_lock(struct lockd
WARN_ON(debug_locks && !lockdep_is_held(l)); \
} while (0)
+#define lockdep_assert_held_exclusive(l) do { \
+ WARN_ON(debug_locks && !lockdep_is_held_type(l, 0)); \
+ } while (0)
+
+#define lockdep_assert_held_read(l) do { \
+ WARN_ON(debug_locks && !lockdep_is_held_type(l, 1)); \
+ } while (0)
+
#define lockdep_assert_held_once(l) do { \
WARN_ON_ONCE(debug_locks && !lockdep_is_held(l)); \
} while (0)
@@ -429,6 +446,8 @@ struct lock_class_key { };
#define lockdep_depth(tsk) (0)
#define lockdep_assert_held(l) do { (void)(l); } while (0)
+#define lockdep_assert_held_exclusive(l) do { (void)(l); } while (0)
+#define lockdep_assert_held_read(l) do { (void)(l); } while (0)
#define lockdep_assert_held_once(l) do { (void)(l); } while (0)
#define lockdep_recursing(tsk) (0)
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3188,7 +3188,7 @@ print_lock_nested_lock_not_held(struct t
return 0;
}
-static int __lock_is_held(struct lockdep_map *lock);
+static int __lock_is_held(struct lockdep_map *lock, int read);
/*
* This gets called for every mutex_lock*()/spin_lock*() operation.
@@ -3329,7 +3329,7 @@ static int __lock_acquire(struct lockdep
}
chain_key = iterate_chain_key(chain_key, class_idx);
- if (nest_lock && !__lock_is_held(nest_lock))
+ if (nest_lock && !__lock_is_held(nest_lock, -1))
return print_lock_nested_lock_not_held(curr, hlock, ip);
if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
@@ -3576,7 +3576,7 @@ __lock_release(struct lockdep_map *lock,
return 1;
}
-static int __lock_is_held(struct lockdep_map *lock)
+static int __lock_is_held(struct lockdep_map *lock, int read)
{
struct task_struct *curr = current;
int i;
@@ -3584,8 +3584,12 @@ static int __lock_is_held(struct lockdep
for (i = 0; i < curr->lockdep_depth; i++) {
struct held_lock *hlock = curr->held_locks + i;
- if (match_held_lock(hlock, lock))
- return 1;
+ if (match_held_lock(hlock, lock)) {
+ if (read == -1 || hlock->read == read)
+ return 1;
+
+ return 0;
+ }
}
return 0;
@@ -3769,7 +3773,7 @@ void lock_release(struct lockdep_map *lo
}
EXPORT_SYMBOL_GPL(lock_release);
-int lock_is_held(struct lockdep_map *lock)
+int lock_is_held_type(struct lockdep_map *lock, int read)
{
unsigned long flags;
int ret = 0;
@@ -3781,13 +3785,13 @@ int lock_is_held(struct lockdep_map *loc
check_flags(flags);
current->lockdep_recursion = 1;
- ret = __lock_is_held(lock);
+ ret = __lock_is_held(lock, read);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
return ret;
}
-EXPORT_SYMBOL_GPL(lock_is_held);
+EXPORT_SYMBOL_GPL(lock_is_held_type);
struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
{
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