The following commit has been merged into the locking/core branch of tip:
Commit-ID: 3e31f94752e454bdd0ca4a1d046ee21f80c166c5
Gitweb: https://git.kernel.org/tip/3e31f94752e454bdd0ca4a1d046ee21f80c166c5
Author: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
AuthorDate: Fri, 26 Feb 2021 17:06:58 -07:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Sat, 06 Mar 2021 12:51:05 +01:00
lockdep: Add lockdep_assert_not_held()
Some kernel functions must be called without holding a specific lock.
Add lockdep_assert_not_held() to be used in these functions to detect
incorrect calls while holding a lock.
lockdep_assert_not_held() provides the opposite functionality of
lockdep_assert_held() which is used to assert calls that require
holding a specific lock.
Incorporates suggestions from Peter Zijlstra to avoid misfires when
lockdep_off() is employed.
The need for lockdep_assert_not_held() came up in a discussion on
ath10k patch. ath10k_drain_tx() and i915_vma_pin_ww() are examples
of functions that can use lockdep_assert_not_held().
Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/linux-wireless/871rdmu9z9.fsf@xxxxxxxxxxxxxx/
---
include/linux/lockdep.h | 11 ++++++++---
kernel/locking/lockdep.c | 6 +++++-
2 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 7b7ebf2..dbd9ea8 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -301,8 +301,12 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
#define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
-#define lockdep_assert_held(l) do { \
- WARN_ON(debug_locks && !lockdep_is_held(l)); \
+#define lockdep_assert_held(l) do { \
+ WARN_ON(debug_locks && lockdep_is_held(l) == 0); \
+ } while (0)
+
+#define lockdep_assert_not_held(l) do { \
+ WARN_ON(debug_locks && lockdep_is_held(l) == 1); \
} while (0)
#define lockdep_assert_held_write(l) do { \
@@ -393,7 +397,8 @@ extern int lockdep_is_held(const void *);
#define lockdep_is_held_type(l, r) (1)
#define lockdep_assert_held(l) do { (void)(l); } while (0)
-#define lockdep_assert_held_write(l) do { (void)(l); } while (0)
+#define lockdep_assert_not_held(l) do { (void)(l); } while (0)
+#define lockdep_assert_held_write(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)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index c6d0c1d..969736b 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -5539,8 +5539,12 @@ noinstr int lock_is_held_type(const struct lockdep_map *lock, int read)
unsigned long flags;
int ret = 0;
+ /*
+ * Avoid false negative lockdep_assert_held() and
+ * lockdep_assert_not_held().
+ */
if (unlikely(!lockdep_enabled()))
- return 1; /* avoid false negative lockdep_assert_held() */
+ return -1;
raw_local_irq_save(flags);
check_flags(flags);
|