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McKenney" , Tejun Heo , Barret Rhoden , Josh Don , Dohyun Kim , linux-arm-kernel@lists.infradead.org, kernel-team@meta.com Subject: [PATCH bpf-next v2 15/26] rqspinlock: Add macros for rqspinlock usage Date: Thu, 6 Feb 2025 02:54:23 -0800 Message-ID: <20250206105435.2159977-16-memxor@gmail.com> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20250206105435.2159977-1-memxor@gmail.com> References: <20250206105435.2159977-1-memxor@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3270; h=from:subject; bh=itMjJLB45N5MLJdgdgQDHOOS7VmFDUaHlV/BKezdr3U=; b=owEBbQKS/ZANAwAIAUzgyIZIvxHKAcsmYgBnpJRmSdisG+iOEzxKLgDdJjXZN/mncOFg8pv5dO3d bZNJg+GJAjMEAAEIAB0WIQRLvip+Buz51YI8YRFM4MiGSL8RygUCZ6SUZgAKCRBM4MiGSL8RyqPRD/ 9gG2FU1oHAJPUn4UJ3fwKsuQm4i95ajoiPlT/m5kT+DPF9gSa+xO4hKuGYliwEJvf+nuxUe7FMhCUo nbsTx4KiQesdJvFLBEyC8lMRvIh0qaD//aym3Fhb4D5zAgaUBULNbyDh5gj/mVvu5FLRbI+DT3LJmw r1bostFusx1GdFieKe+yhrTChSjrfqKbnpY9R/8w5UkGN/g+vLsyykEbwnbgHhL0Ycvk+yqbXaob++ hWud3ejpfkcyQRqDBeycTn+q3cMN4T33wASR6VfBgNAggDQplTQ0NL97l+Dn3qdgtj1L8+PzWkyEy7 uzYnLPsU1re215zb4P38apAspYJP0lf30MOhhmObWuxKLqtviREsn0uOBZNsmdc4R3mfydqsDy2K3i fXrNShGCY4YJFjLqUeWDnW9g2IHVA0Y3GNq49DhGgN8ZGExFHkkLHKfWWt1vd80tJx+3FcaAcbrHN6 jqnPSeoZw9H/Gv0GIoXD05hjLkUhPcZYt3gM2eUbE0LjEPwU3A1PAq0320Z5j0ZxsuHnEQt80v5ElR 1N2IG2VJNeILB6c4gNBsyn59IW7xvMo0y6wnEpgTgAJHBxYZqffi0Js1mYt58TEIo6iaH05Sdjgvz5 U5PZ/7rUM15c0KeEcHBAwD6NKswh6LfL192Y9X7h+EChg4E+eQnBkpyXm7gw== X-Developer-Key: i=memxor@gmail.com; a=openpgp; fpr=4BBE2A7E06ECF9D5823C61114CE0C88648BF11CA X-Patchwork-Delegate: bpf@iogearbox.net Introduce helper macros that wrap around the rqspinlock slow path and provide an interface analogous to the raw_spin_lock API. Note that in case of error conditions, preemption and IRQ disabling is automatically unrolled before returning the error back to the caller. Ensure that in absence of CONFIG_QUEUED_SPINLOCKS support, we fallback to the test-and-set implementation. Signed-off-by: Kumar Kartikeya Dwivedi --- include/asm-generic/rqspinlock.h | 71 ++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) diff --git a/include/asm-generic/rqspinlock.h b/include/asm-generic/rqspinlock.h index bbe049dcf70d..46119fc768b8 100644 --- a/include/asm-generic/rqspinlock.h +++ b/include/asm-generic/rqspinlock.h @@ -134,4 +134,75 @@ static __always_inline void release_held_lock_entry(void) smp_wmb(); } +#ifdef CONFIG_QUEUED_SPINLOCKS + +/** + * res_spin_lock - acquire a queued spinlock + * @lock: Pointer to queued spinlock structure + */ +static __always_inline int res_spin_lock(rqspinlock_t *lock) +{ + int val = 0; + + if (likely(atomic_try_cmpxchg_acquire(&lock->val, &val, _Q_LOCKED_VAL))) { + grab_held_lock_entry(lock); + return 0; + } + return resilient_queued_spin_lock_slowpath(lock, val, RES_DEF_TIMEOUT); +} + +#else + +#define res_spin_lock(lock) resilient_tas_spin_lock(lock, RES_DEF_TIMEOUT) + +#endif /* CONFIG_QUEUED_SPINLOCKS */ + +static __always_inline void res_spin_unlock(rqspinlock_t *lock) +{ + struct rqspinlock_held *rqh = this_cpu_ptr(&rqspinlock_held_locks); + + if (unlikely(rqh->cnt > RES_NR_HELD)) + goto unlock; + WRITE_ONCE(rqh->locks[rqh->cnt - 1], NULL); +unlock: + this_cpu_dec(rqspinlock_held_locks.cnt); + /* + * Release barrier, ensures correct ordering. See release_held_lock_entry + * for details. Perform release store instead of queued_spin_unlock, + * since we use this function for test-and-set fallback as well. When we + * have CONFIG_QUEUED_SPINLOCKS=n, we clear the full 4-byte lockword. + */ + smp_store_release(&lock->locked, 0); +} + +#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_lock(lock) \ + ({ \ + int __ret; \ + preempt_disable(); \ + __ret = res_spin_lock(lock); \ + if (__ret) \ + preempt_enable(); \ + __ret; \ + }) + +#define raw_res_spin_unlock(lock) ({ res_spin_unlock(lock); preempt_enable(); }) + +#define raw_res_spin_lock_irqsave(lock, flags) \ + ({ \ + int __ret; \ + local_irq_save(flags); \ + __ret = raw_res_spin_lock(lock); \ + if (__ret) \ + local_irq_restore(flags); \ + __ret; \ + }) + +#define raw_res_spin_unlock_irqrestore(lock, flags) ({ raw_res_spin_unlock(lock); local_irq_restore(flags); }) + #endif /* __ASM_GENERIC_RQSPINLOCK_H */