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[24.9.64.241]) by smtp.gmail.com with ESMTPSA id w16sm5228805ilh.35.2021.02.26.16.07.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Feb 2021 16:07:03 -0800 (PST) From: Shuah Khan To: peterz@infradead.org, mingo@redhat.com, will@kernel.org, kvalo@codeaurora.org, davem@davemloft.net, kuba@kernel.org Cc: Shuah Khan , 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 Message-Id: X-Mailer: git-send-email 2.27.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.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 --- 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