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[192.26.29.3]) by smtp.gmail.com with UTF8SMTPSA id 5b1f17b1804b1-477bf216ddasm221605385e9.0.2025.11.24.19.08.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Nov 2025 19:08:59 -0800 (PST) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Martin KaFai Lau , Eduard Zingerman , kkd@meta.com, kernel-team@meta.com Subject: [PATCH bpf-next v1] rqspinlock: Introduce res_spin_trylock Date: Tue, 25 Nov 2025 03:08:58 +0000 Message-ID: <20251125030858.2485401-1-memxor@gmail.com> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A trylock variant for rqspinlock was missing owing to lack of users in the tree thus far, add one now as it would be needed in subsequent patches. Mark as __must_check and __always_inline. This essentially copies queued_spin_trylock, but doesn't depend on it as rqspinlock compiles down to a TAS when CONFIG_QUEUED_SPINLOCKS=n. Signed-off-by: Kumar Kartikeya Dwivedi --- include/asm-generic/rqspinlock.h | 45 ++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/include/asm-generic/rqspinlock.h b/include/asm-generic/rqspinlock.h index 6d4244d643df3..a7f4b7c0fb78a 100644 --- a/include/asm-generic/rqspinlock.h +++ b/include/asm-generic/rqspinlock.h @@ -217,12 +217,57 @@ static __always_inline void res_spin_unlock(rqspinlock_t *lock) this_cpu_dec(rqspinlock_held_locks.cnt); } +/** + * res_spin_trylock - try to acquire a queued spinlock + * @lock: Pointer to queued spinlock structure + * + * Attempts to acquire the lock without blocking. This function should be used + * in contexts where blocking is not allowed (e.g., NMI handlers). + * + * Return: + * * 1 - Lock was acquired successfully. + * * 0 - Lock acquisition failed. + */ +static __must_check __always_inline int res_spin_trylock(rqspinlock_t *lock) +{ + int val = atomic_read(&lock->val); + int ret; + + if (unlikely(val)) + return 0; + + ret = likely(atomic_try_cmpxchg_acquire(&lock->val, &val, 1)); + if (ret) + grab_held_lock_entry(lock); + return ret; +} + #ifdef CONFIG_QUEUED_SPINLOCKS #define raw_res_spin_lock_init(lock) ({ *(lock) = (rqspinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; }) #else #define raw_res_spin_lock_init(lock) ({ *(lock) = (rqspinlock_t){0}; }) #endif +#define raw_res_spin_trylock(lock) \ + ({ \ + int __ret; \ + preempt_disable(); \ + __ret = res_spin_trylock(lock); \ + if (!__ret) \ + preempt_enable(); \ + __ret; \ + }) + +#define raw_res_spin_trylock_irqsave(lock, flags) \ + ({ \ + int __ret; \ + local_irq_save(flags); \ + __ret = raw_res_spin_trylock(lock); \ + if (!__ret) \ + local_irq_restore(flags); \ + __ret; \ + }) + #define raw_res_spin_lock(lock) \ ({ \ int __ret; \