Commit-ID: e0d02285f16e8d5810f3d5d5e8a5886ca0015d3b Gitweb: https://git.kernel.org/tip/e0d02285f16e8d5810f3d5d5e8a5886ca0015d3b Author: Will Deacon <will.dea...@arm.com> AuthorDate: Thu, 12 Oct 2017 13:20:47 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Wed, 25 Oct 2017 10:57:24 +0200
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.dea...@arm.com> Acked-by: Peter Zijlstra <pet...@infradead.org> Cc: Boqun Feng <boqun.f...@gmail.com> Cc: jeremy.lin...@arm.com Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Waiman Long <long...@redhat.com> Cc: linux-arm-ker...@lists.infradead.org Link: http://lkml.kernel.org/r/1507810851-306-2-git-send-email-will.dea...@arm.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- include/asm-generic/qrwlock.h | 12 +----------- include/asm-generic/qrwlock_types.h | 15 +++++++++++++-- kernel/locking/qrwlock.c | 26 ++------------------------ 3 files changed, 16 insertions(+), 37 deletions(-) diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h index 5092532..02c0a76 100644 --- a/include/asm-generic/qrwlock.h +++ b/include/asm-generic/qrwlock.h @@ -129,22 +129,12 @@ static inline void queued_read_unlock(struct qrwlock *lock) } /** - * __qrwlock_write_byte - retrieve the write byte address of a queue rwlock - * @lock : Pointer to queue rwlock structure - * Return: the write byte address of a queue rwlock - */ -static inline u8 *__qrwlock_write_byte(struct qrwlock *lock) -{ - return (u8 *)lock + 3 * IS_BUILTIN(CONFIG_CPU_BIG_ENDIAN); -} - -/** * queued_write_unlock - release write lock of a queue rwlock * @lock : Pointer to queue rwlock structure */ static inline void queued_write_unlock(struct qrwlock *lock) { - smp_store_release(__qrwlock_write_byte(lock), 0); + smp_store_release(&lock->wmode, 0); } /* diff --git a/include/asm-generic/qrwlock_types.h b/include/asm-generic/qrwlock_types.h index 0abc6b6..507f2dc 100644 --- a/include/asm-generic/qrwlock_types.h +++ b/include/asm-generic/qrwlock_types.h @@ -9,12 +9,23 @@ */ typedef struct qrwlock { - atomic_t cnts; + union { + atomic_t cnts; + struct { +#ifdef __LITTLE_ENDIAN + u8 wmode; /* Writer mode */ + u8 rcnts[3]; /* Reader counts */ +#else + u8 rcnts[3]; /* Reader counts */ + u8 wmode; /* Writer mode */ +#endif + }; + }; arch_spinlock_t wait_lock; } arch_rwlock_t; #define __ARCH_RW_LOCK_UNLOCKED { \ - .cnts = ATOMIC_INIT(0), \ + { .cnts = ATOMIC_INIT(0), }, \ .wait_lock = __ARCH_SPIN_LOCK_UNLOCKED, \ } diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c index 2655f26..1af791e 100644 --- a/kernel/locking/qrwlock.c +++ b/kernel/locking/qrwlock.c @@ -23,26 +23,6 @@ #include <linux/spinlock.h> #include <asm/qrwlock.h> -/* - * This internal data structure is used for optimizing access to some of - * the subfields within the atomic_t cnts. - */ -struct __qrwlock { - union { - atomic_t cnts; - struct { -#ifdef __LITTLE_ENDIAN - u8 wmode; /* Writer mode */ - u8 rcnts[3]; /* Reader counts */ -#else - u8 rcnts[3]; /* Reader counts */ - u8 wmode; /* Writer mode */ -#endif - }; - }; - arch_spinlock_t lock; -}; - /** * rspin_until_writer_unlock - inc reader count & spin until writer is gone * @lock : Pointer to queue rwlock structure @@ -125,10 +105,8 @@ void queued_write_lock_slowpath(struct qrwlock *lock) * or wait for a previous writer to go away. */ for (;;) { - struct __qrwlock *l = (struct __qrwlock *)lock; - - if (!READ_ONCE(l->wmode) && - (cmpxchg_relaxed(&l->wmode, 0, _QW_WAITING) == 0)) + if (!READ_ONCE(lock->wmode) && + (cmpxchg_relaxed(&lock->wmode, 0, _QW_WAITING) == 0)) break; cpu_relax();
