locking/qrwlock: Use 'struct qrwlock' instead of 'struct __qrwlock'
There's no good reason to keep the internal structure of struct qrwlock hidden from qrwlock.h, particularly as it's actually needed for unlock and ends up being abstracted independently behind the __qrwlock_write_byte() function. Stop pretending we can hide this stuff, and move the __qrwlock definition into qrwlock, removing the __qrwlock_write_byte() nastiness and using the same struct definition everywhere instead. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Jeremy.Linton@arm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <longman@redhat.com> Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1507810851-306-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -128,23 +128,13 @@ static inline void queued_read_unlock(struct qrwlock *lock)
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(void)atomic_sub_return_release(_QR_BIAS, &lock->cnts);
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(void)atomic_sub_return_release(_QR_BIAS, &lock->cnts);
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}
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}
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/**
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* __qrwlock_write_byte - retrieve the write byte address of a queue rwlock
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* @lock : Pointer to queue rwlock structure
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* Return: the write byte address of a queue rwlock
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*/
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static inline u8 *__qrwlock_write_byte(struct qrwlock *lock)
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{
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return (u8 *)lock + 3 * IS_BUILTIN(CONFIG_CPU_BIG_ENDIAN);
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}
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/**
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/**
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* queued_write_unlock - release write lock of a queue rwlock
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* queued_write_unlock - release write lock of a queue rwlock
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* @lock : Pointer to queue rwlock structure
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* @lock : Pointer to queue rwlock structure
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*/
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*/
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static inline void queued_write_unlock(struct qrwlock *lock)
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static inline void queued_write_unlock(struct qrwlock *lock)
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{
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{
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smp_store_release(__qrwlock_write_byte(lock), 0);
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smp_store_release(&lock->wmode, 0);
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}
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}
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/*
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/*
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@ -9,12 +9,23 @@
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*/
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*/
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typedef struct qrwlock {
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typedef struct qrwlock {
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atomic_t cnts;
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union {
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atomic_t cnts;
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struct {
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#ifdef __LITTLE_ENDIAN
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u8 wmode; /* Writer mode */
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u8 rcnts[3]; /* Reader counts */
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#else
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u8 rcnts[3]; /* Reader counts */
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u8 wmode; /* Writer mode */
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#endif
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};
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};
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arch_spinlock_t wait_lock;
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arch_spinlock_t wait_lock;
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} arch_rwlock_t;
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} arch_rwlock_t;
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#define __ARCH_RW_LOCK_UNLOCKED { \
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#define __ARCH_RW_LOCK_UNLOCKED { \
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.cnts = ATOMIC_INIT(0), \
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{ .cnts = ATOMIC_INIT(0), }, \
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.wait_lock = __ARCH_SPIN_LOCK_UNLOCKED, \
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.wait_lock = __ARCH_SPIN_LOCK_UNLOCKED, \
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}
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}
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@ -23,26 +23,6 @@
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#include <linux/spinlock.h>
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#include <linux/spinlock.h>
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#include <asm/qrwlock.h>
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#include <asm/qrwlock.h>
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/*
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* This internal data structure is used for optimizing access to some of
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* the subfields within the atomic_t cnts.
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*/
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struct __qrwlock {
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union {
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atomic_t cnts;
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struct {
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#ifdef __LITTLE_ENDIAN
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u8 wmode; /* Writer mode */
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u8 rcnts[3]; /* Reader counts */
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#else
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u8 rcnts[3]; /* Reader counts */
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u8 wmode; /* Writer mode */
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#endif
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};
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};
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arch_spinlock_t lock;
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};
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/**
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/**
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* rspin_until_writer_unlock - inc reader count & spin until writer is gone
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* rspin_until_writer_unlock - inc reader count & spin until writer is gone
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* @lock : Pointer to queue rwlock structure
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* @lock : Pointer to queue rwlock structure
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@ -125,10 +105,8 @@ void queued_write_lock_slowpath(struct qrwlock *lock)
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* or wait for a previous writer to go away.
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* or wait for a previous writer to go away.
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*/
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*/
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for (;;) {
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for (;;) {
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struct __qrwlock *l = (struct __qrwlock *)lock;
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if (!READ_ONCE(lock->wmode) &&
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(cmpxchg_relaxed(&lock->wmode, 0, _QW_WAITING) == 0))
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if (!READ_ONCE(l->wmode) &&
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(cmpxchg_relaxed(&l->wmode, 0, _QW_WAITING) == 0))
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break;
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break;
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cpu_relax();
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cpu_relax();
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