From: Shuah Khan <skhan@linuxfoundation.org>
To: peterz@infradead.org, mingo@redhat.com, will@kernel.org,
kvalo@codeaurora.org, davem@davemloft.net, kuba@kernel.org
Cc: Shuah Khan <skhan@linuxfoundation.org>,
ath10k@lists.infradead.org, linux-wireless@vger.kernel.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v3 1/3] lockdep: add lockdep_assert_not_held()
Date: Fri, 26 Feb 2021 17:06:58 -0700 [thread overview]
Message-ID: <c22a1c5ef8a7620dce02c26993b998777d432aac.1614383025.git.skhan@linuxfoundation.org> (raw)
In-Reply-To: <cover.1614383025.git.skhan@linuxfoundation.org>
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().
Link: https://lore.kernel.org/lkml/37a29c383bff2fb1605241ee6c7c9be3784fb3c6.1613171185.git.skhan@linuxfoundation.org/
Link: https://lore.kernel.org/linux-wireless/871rdmu9z9.fsf@codeaurora.org/
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
---
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 7b7ebf2e28ec..dbd9ea846b36 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 c6d0c1dc6253..818d0ceed3eb 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);
--
2.27.0
next prev parent reply other threads:[~2021-02-27 0:09 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-27 0:06 [PATCH v3 0/3] Add lockdep_assert_not_held() Shuah Khan
2021-02-27 0:06 ` Shuah Khan [this message]
2021-02-27 0:06 ` [PATCH v3 2/3] lockdep: add lockdep lock state defines Shuah Khan
2021-02-27 0:07 ` [PATCH v3 3/3] ath10k: detect conf_mutex held ath10k_drain_tx() calls Shuah Khan
2021-03-01 8:38 ` [PATCH v3 0/3] Add lockdep_assert_not_held() Peter Zijlstra
2021-03-01 8:45 ` Kalle Valo
2021-03-01 9:36 ` Peter Zijlstra
2021-03-01 11:02 ` Kalle Valo
2021-03-01 16:04 ` Shuah Khan
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