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https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
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b85aa9b11b
The compiler might decide that it is a smart idea to not inline bit_spin_lock(), primarily when a couple of functions in the same file end up calling it. Especially when used in RMAP map/unmap code next, the compiler sometimes decides to not inline, which is then observable in some micro-benchmarks. Let's simply flag all lock/unlock functions as __always_inline; arch_test_and_set_bit_lock() and friends are already tagged like that (but not test_and_set_bit_lock() for some reason). If ever a problem, we could split it into a fast and a slow path, and only force the fast path to be inlined. But there is nothing particularly "big" here. Link: https://lkml.kernel.org/r/20250303163014.1128035-11-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Andy Lutomirks^H^Hski <luto@kernel.org> Cc: Borislav Betkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lance Yang <ioworker0@gmail.com> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Matthew Wilcow (Oracle) <willy@infradead.org> Cc: Michal Koutn <mkoutny@suse.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: tejun heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zefan Li <lizefan.x@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
102 lines
2.3 KiB
C
102 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_BIT_SPINLOCK_H
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#define __LINUX_BIT_SPINLOCK_H
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#include <linux/kernel.h>
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#include <linux/preempt.h>
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#include <linux/atomic.h>
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#include <linux/bug.h>
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/*
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* bit-based spin_lock()
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*
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* Don't use this unless you really need to: spin_lock() and spin_unlock()
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* are significantly faster.
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*/
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static __always_inline void bit_spin_lock(int bitnum, unsigned long *addr)
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{
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/*
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* Assuming the lock is uncontended, this never enters
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* the body of the outer loop. If it is contended, then
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* within the inner loop a non-atomic test is used to
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* busywait with less bus contention for a good time to
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* attempt to acquire the lock bit.
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*/
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preempt_disable();
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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while (unlikely(test_and_set_bit_lock(bitnum, addr))) {
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preempt_enable();
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do {
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cpu_relax();
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} while (test_bit(bitnum, addr));
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preempt_disable();
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}
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#endif
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__acquire(bitlock);
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}
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/*
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* Return true if it was acquired
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*/
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static __always_inline int bit_spin_trylock(int bitnum, unsigned long *addr)
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{
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preempt_disable();
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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if (unlikely(test_and_set_bit_lock(bitnum, addr))) {
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preempt_enable();
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return 0;
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}
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#endif
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__acquire(bitlock);
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return 1;
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}
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/*
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* bit-based spin_unlock()
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*/
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static __always_inline void bit_spin_unlock(int bitnum, unsigned long *addr)
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{
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#ifdef CONFIG_DEBUG_SPINLOCK
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BUG_ON(!test_bit(bitnum, addr));
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#endif
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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clear_bit_unlock(bitnum, addr);
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#endif
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preempt_enable();
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__release(bitlock);
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}
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/*
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* bit-based spin_unlock()
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* non-atomic version, which can be used eg. if the bit lock itself is
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* protecting the rest of the flags in the word.
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*/
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static __always_inline void __bit_spin_unlock(int bitnum, unsigned long *addr)
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{
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#ifdef CONFIG_DEBUG_SPINLOCK
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BUG_ON(!test_bit(bitnum, addr));
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#endif
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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__clear_bit_unlock(bitnum, addr);
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#endif
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preempt_enable();
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__release(bitlock);
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}
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/*
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* Return true if the lock is held.
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*/
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static inline int bit_spin_is_locked(int bitnum, unsigned long *addr)
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{
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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return test_bit(bitnum, addr);
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#elif defined CONFIG_PREEMPT_COUNT
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return preempt_count();
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#else
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return 1;
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#endif
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}
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#endif /* __LINUX_BIT_SPINLOCK_H */
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