mirror of
https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10.git
synced 2026-09-09 00:07:04 +08:00
Rafael Aquini
9616c77fa5
JIRA: https://redhat.atlassian.net/browse/RHEL-145694 commit b85aa9b11b67ed4b086bf5366392adec1b4a6a81 Author: David Hildenbrand <david@redhat.com> Date: Mon Mar 3 17:30:03 2025 +0100 bit_spinlock: __always_inline (un)lock functions 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> Signed-off-by: Rafael Aquini <raquini@redhat.com>
102 lines
2.3 KiB
C
102 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef __LINUX_BIT_SPINLOCK_H
|
|
#define __LINUX_BIT_SPINLOCK_H
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/preempt.h>
|
|
#include <linux/atomic.h>
|
|
#include <linux/bug.h>
|
|
|
|
/*
|
|
* bit-based spin_lock()
|
|
*
|
|
* Don't use this unless you really need to: spin_lock() and spin_unlock()
|
|
* are significantly faster.
|
|
*/
|
|
static __always_inline void bit_spin_lock(int bitnum, unsigned long *addr)
|
|
{
|
|
/*
|
|
* Assuming the lock is uncontended, this never enters
|
|
* the body of the outer loop. If it is contended, then
|
|
* within the inner loop a non-atomic test is used to
|
|
* busywait with less bus contention for a good time to
|
|
* attempt to acquire the lock bit.
|
|
*/
|
|
preempt_disable();
|
|
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
|
|
while (unlikely(test_and_set_bit_lock(bitnum, addr))) {
|
|
preempt_enable();
|
|
do {
|
|
cpu_relax();
|
|
} while (test_bit(bitnum, addr));
|
|
preempt_disable();
|
|
}
|
|
#endif
|
|
__acquire(bitlock);
|
|
}
|
|
|
|
/*
|
|
* Return true if it was acquired
|
|
*/
|
|
static __always_inline int bit_spin_trylock(int bitnum, unsigned long *addr)
|
|
{
|
|
preempt_disable();
|
|
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
|
|
if (unlikely(test_and_set_bit_lock(bitnum, addr))) {
|
|
preempt_enable();
|
|
return 0;
|
|
}
|
|
#endif
|
|
__acquire(bitlock);
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* bit-based spin_unlock()
|
|
*/
|
|
static __always_inline void bit_spin_unlock(int bitnum, unsigned long *addr)
|
|
{
|
|
#ifdef CONFIG_DEBUG_SPINLOCK
|
|
BUG_ON(!test_bit(bitnum, addr));
|
|
#endif
|
|
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
|
|
clear_bit_unlock(bitnum, addr);
|
|
#endif
|
|
preempt_enable();
|
|
__release(bitlock);
|
|
}
|
|
|
|
/*
|
|
* bit-based spin_unlock()
|
|
* non-atomic version, which can be used eg. if the bit lock itself is
|
|
* protecting the rest of the flags in the word.
|
|
*/
|
|
static __always_inline void __bit_spin_unlock(int bitnum, unsigned long *addr)
|
|
{
|
|
#ifdef CONFIG_DEBUG_SPINLOCK
|
|
BUG_ON(!test_bit(bitnum, addr));
|
|
#endif
|
|
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
|
|
__clear_bit_unlock(bitnum, addr);
|
|
#endif
|
|
preempt_enable();
|
|
__release(bitlock);
|
|
}
|
|
|
|
/*
|
|
* Return true if the lock is held.
|
|
*/
|
|
static inline int bit_spin_is_locked(int bitnum, unsigned long *addr)
|
|
{
|
|
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
|
|
return test_bit(bitnum, addr);
|
|
#elif defined CONFIG_PREEMPT_COUNT
|
|
return preempt_count();
|
|
#else
|
|
return 1;
|
|
#endif
|
|
}
|
|
|
|
#endif /* __LINUX_BIT_SPINLOCK_H */
|
|
|