| Message ID | a40d18bba5a52662ac8fc556e1fce3752ea08472.1614355914.git.skhan@linuxfoundation.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Johannes Berg |
| Headers | show |
| Series | Add lockdep_assert_not_held() | expand |
On Fri, Feb 26, 2021 at 10:52:13AM -0700, Shuah Khan wrote: > + /* avoid false negative lockdep_assert_not_held() > + * and lockdep_assert_held() > + */ That's a coding style fail.
On 2/26/21 2:07 PM, Peter Zijlstra wrote: > On Fri, Feb 26, 2021 at 10:52:13AM -0700, Shuah Khan wrote: >> + /* avoid false negative lockdep_assert_not_held() >> + * and lockdep_assert_held() >> + */ > > That's a coding style fail. > Checkpatch didn't complain. What's your preference? Does the following work for you? /* * avoid false negative lockdep_assert_not_held() * and lockdep_assert_held() */ thanks, -- Shuah
On Fri, Feb 26, 2021 at 02:16:12PM -0700, Shuah Khan wrote: > On 2/26/21 2:07 PM, Peter Zijlstra wrote: > > On Fri, Feb 26, 2021 at 10:52:13AM -0700, Shuah Khan wrote: > > > + /* avoid false negative lockdep_assert_not_held() > > > + * and lockdep_assert_held() > > > + */ > > > > That's a coding style fail. > > > > Checkpatch didn't complain. Documentation/CodingStyle (or whatever unreadable rst crap it is today :-( ) and: https://lkml.kernel.org/lkml/CA+55aFyQYJerovMsSoSKS7PessZBr4vNp-3QUUwhqk4A4_jcbg@mail.gmail.com/ > What's your preference? Does the following work for you? > > /* > * avoid false negative lockdep_assert_not_held() > * and lockdep_assert_held() > */ Yep (ideally even with a Capital and full stop).
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index b9e9adec73e8..93eb5f797fc1 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -294,8 +294,12 @@ 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 { \ @@ -384,7 +388,8 @@ 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 bdaf4829098c..d3299fd85c4a 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -5472,7 +5472,10 @@ noinstr int lock_is_held_type(const struct lockdep_map *lock, int read) int ret = 0; if (unlikely(!lockdep_enabled())) - return 1; /* avoid false negative lockdep_assert_held() */ + /* avoid false negative lockdep_assert_not_held() + * and lockdep_assert_held() + */ + return -1; raw_local_irq_save(flags); check_flags(flags);
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 | 5 ++++- 2 files changed, 12 insertions(+), 4 deletions(-)