From a8a217c22116eff6c120d753c9934089fb229af0 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Tue, 3 Oct 2017 19:25:27 +0100 Subject: locking/core: Remove {read,spin,write}_can_lock() Outside of the locking code itself, {read,spin,write}_can_lock() have no users in tree. Apparmor (the last remaining user of write_can_lock()) got moved over to lockdep by the previous patch. This patch removes the use of {read,spin,write}_can_lock() from the BUILD_LOCK_OPS macro, deferring to the trylock operation for testing the lock status, and subsequently removes the unused macros altogether. They aren't guaranteed to work in a concurrent environment and can give incorrect results in the case of qrwlock. Signed-off-by: Will Deacon Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1507055129-12300-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar --- arch/alpha/include/asm/spinlock.h | 10 ---------- arch/arc/include/asm/spinlock.h | 3 --- arch/arm/include/asm/spinlock.h | 6 ------ arch/blackfin/include/asm/spinlock.h | 10 ---------- arch/hexagon/include/asm/spinlock.h | 10 ---------- arch/ia64/include/asm/spinlock.h | 3 --- arch/m32r/include/asm/spinlock.h | 12 ------------ arch/metag/include/asm/spinlock_lnkget.h | 30 ------------------------------ arch/metag/include/asm/spinlock_lock1.h | 20 -------------------- arch/mn10300/include/asm/spinlock.h | 12 ------------ arch/parisc/include/asm/spinlock.h | 18 ------------------ arch/powerpc/include/asm/spinlock.h | 3 --- arch/s390/include/asm/spinlock.h | 12 ------------ arch/sh/include/asm/spinlock-cas.h | 12 ------------ arch/sh/include/asm/spinlock-llsc.h | 12 ------------ arch/sparc/include/asm/spinlock_32.h | 3 --- arch/tile/include/asm/spinlock_32.h | 16 ---------------- arch/tile/include/asm/spinlock_64.h | 18 ------------------ arch/xtensa/include/asm/spinlock.h | 2 -- include/asm-generic/qrwlock.h | 20 -------------------- include/linux/rwlock.h | 3 --- include/linux/spinlock.h | 11 ----------- include/linux/spinlock_up.h | 3 --- kernel/locking/spinlock.c | 6 ++---- 24 files changed, 2 insertions(+), 253 deletions(-) diff --git a/arch/alpha/include/asm/spinlock.h b/arch/alpha/include/asm/spinlock.h index 718ac0b..7bff6316 100644 --- a/arch/alpha/include/asm/spinlock.h +++ b/arch/alpha/include/asm/spinlock.h @@ -54,16 +54,6 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock) /***********************************************************/ -static inline int arch_read_can_lock(arch_rwlock_t *lock) -{ - return (lock->lock & 1) == 0; -} - -static inline int arch_write_can_lock(arch_rwlock_t *lock) -{ - return lock->lock == 0; -} - static inline void arch_read_lock(arch_rwlock_t *lock) { long regx; diff --git a/arch/arc/include/asm/spinlock.h b/arch/arc/include/asm/spinlock.h index 47efc84..ce9bfcf 100644 --- a/arch/arc/include/asm/spinlock.h +++ b/arch/arc/include/asm/spinlock.h @@ -410,9 +410,6 @@ static inline void arch_write_unlock(arch_rwlock_t *rw) #endif -#define arch_read_can_lock(x) ((x)->counter > 0) -#define arch_write_can_lock(x) ((x)->counter == __ARCH_RW_LOCK_UNLOCKED__) - #define arch_read_lock_flags(lock, flags) arch_read_lock(lock) #define arch_write_lock_flags(lock, flags) arch_write_lock(lock) diff --git a/arch/arm/include/asm/spinlock.h b/arch/arm/include/asm/spinlock.h index c030143..f522326 100644 --- a/arch/arm/include/asm/spinlock.h +++ b/arch/arm/include/asm/spinlock.h @@ -193,9 +193,6 @@ static inline void arch_write_unlock(arch_rwlock_t *rw) dsb_sev(); } -/* write_can_lock - would write_trylock() succeed? */ -#define arch_write_can_lock(x) (ACCESS_ONCE((x)->lock) == 0) - /* * Read locks are a bit more hairy: * - Exclusively load the lock value. @@ -273,9 +270,6 @@ static inline int arch_read_trylock(arch_rwlock_t *rw) } } -/* read_can_lock - would read_trylock() succeed? */ -#define arch_read_can_lock(x) (ACCESS_ONCE((x)->lock) < 0x80000000) - #define arch_read_lock_flags(lock, flags) arch_read_lock(lock) #define arch_write_lock_flags(lock, flags) arch_write_lock(lock) diff --git a/arch/blackfin/include/asm/spinlock.h b/arch/blackfin/include/asm/spinlock.h index f643143..607ef98 100644 --- a/arch/blackfin/include/asm/spinlock.h +++ b/arch/blackfin/include/asm/spinlock.h @@ -48,16 +48,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) __raw_spin_unlock_asm(&lock->lock); } -static inline int arch_read_can_lock(arch_rwlock_t *rw) -{ - return __raw_uncached_fetch_asm(&rw->lock) > 0; -} - -static inline int arch_write_can_lock(arch_rwlock_t *rw) -{ - return __raw_uncached_fetch_asm(&rw->lock) == RW_LOCK_BIAS; -} - static inline void arch_read_lock(arch_rwlock_t *rw) { __raw_read_lock_asm(&rw->lock); diff --git a/arch/hexagon/include/asm/spinlock.h b/arch/hexagon/include/asm/spinlock.h index 53a8d58..9f9414b 100644 --- a/arch/hexagon/include/asm/spinlock.h +++ b/arch/hexagon/include/asm/spinlock.h @@ -86,16 +86,6 @@ static inline int arch_read_trylock(arch_rwlock_t *lock) return temp; } -static inline int arch_read_can_lock(arch_rwlock_t *rwlock) -{ - return rwlock->lock == 0; -} - -static inline int arch_write_can_lock(arch_rwlock_t *rwlock) -{ - return rwlock->lock == 0; -} - /* Stuffs a -1 in the lock value? */ static inline void arch_write_lock(arch_rwlock_t *lock) { diff --git a/arch/ia64/include/asm/spinlock.h b/arch/ia64/include/asm/spinlock.h index df2c121..c728dda 100644 --- a/arch/ia64/include/asm/spinlock.h +++ b/arch/ia64/include/asm/spinlock.h @@ -127,9 +127,6 @@ static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock, arch_spin_lock(lock); } -#define arch_read_can_lock(rw) (*(volatile int *)(rw) >= 0) -#define arch_write_can_lock(rw) (*(volatile int *)(rw) == 0) - #ifdef ASM_SUPPORTED static __always_inline void diff --git a/arch/m32r/include/asm/spinlock.h b/arch/m32r/include/asm/spinlock.h index a568255..0026013 100644 --- a/arch/m32r/include/asm/spinlock.h +++ b/arch/m32r/include/asm/spinlock.h @@ -137,18 +137,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) * semaphore.h for details. -ben */ -/** - * read_can_lock - would read_trylock() succeed? - * @lock: the rwlock in question. - */ -#define arch_read_can_lock(x) ((int)(x)->lock > 0) - -/** - * write_can_lock - would write_trylock() succeed? - * @lock: the rwlock in question. - */ -#define arch_write_can_lock(x) ((x)->lock == RW_LOCK_BIAS) - static inline void arch_read_lock(arch_rwlock_t *rw) { unsigned long tmp0, tmp1; diff --git a/arch/metag/include/asm/spinlock_lnkget.h b/arch/metag/include/asm/spinlock_lnkget.h index ad8436f..6a932a9 100644 --- a/arch/metag/include/asm/spinlock_lnkget.h +++ b/arch/metag/include/asm/spinlock_lnkget.h @@ -136,21 +136,6 @@ static inline void arch_write_unlock(arch_rwlock_t *rw) : "memory"); } -/* write_can_lock - would write_trylock() succeed? */ -static inline int arch_write_can_lock(arch_rwlock_t *rw) -{ - int ret; - - asm volatile ("LNKGETD %0, [%1]\n" - "CMP %0, #0\n" - "MOV %0, #1\n" - "XORNZ %0, %0, %0\n" - : "=&d" (ret) - : "da" (&rw->lock) - : "cc"); - return ret; -} - /* * Read locks are a bit more hairy: * - Exclusively load the lock value. @@ -224,21 +209,6 @@ static inline int arch_read_trylock(arch_rwlock_t *rw) return tmp; } -/* read_can_lock - would read_trylock() succeed? */ -static inline int arch_read_can_lock(arch_rwlock_t *rw) -{ - int tmp; - - asm volatile ("LNKGETD %0, [%1]\n" - "CMP %0, %2\n" - "MOV %0, #1\n" - "XORZ %0, %0, %0\n" - : "=&d" (tmp) - : "da" (&rw->lock), "bd" (0x80000000) - : "cc"); - return tmp; -} - #define arch_read_lock_flags(lock, flags) arch_read_lock(lock) #define arch_write_lock_flags(lock, flags) arch_write_lock(lock) diff --git a/arch/metag/include/asm/spinlock_lock1.h b/arch/metag/include/asm/spinlock_lock1.h index c630444..8ae12bf 100644 --- a/arch/metag/include/asm/spinlock_lock1.h +++ b/arch/metag/include/asm/spinlock_lock1.h @@ -104,16 +104,6 @@ static inline void arch_write_unlock(arch_rwlock_t *rw) rw->lock = 0; } -/* write_can_lock - would write_trylock() succeed? */ -static inline int arch_write_can_lock(arch_rwlock_t *rw) -{ - unsigned int ret; - - barrier(); - ret = rw->lock; - return (ret == 0); -} - /* * Read locks are a bit more hairy: * - Exclusively load the lock value. @@ -171,14 +161,4 @@ static inline int arch_read_trylock(arch_rwlock_t *rw) return (ret < 0x80000000); } -/* read_can_lock - would read_trylock() succeed? */ -static inline int arch_read_can_lock(arch_rwlock_t *rw) -{ - unsigned int ret; - - barrier(); - ret = rw->lock; - return (ret < 0x80000000); -} - #endif /* __ASM_SPINLOCK_LOCK1_H */ diff --git a/arch/mn10300/include/asm/spinlock.h b/arch/mn10300/include/asm/spinlock.h index fe413b4..54f75da 100644 --- a/arch/mn10300/include/asm/spinlock.h +++ b/arch/mn10300/include/asm/spinlock.h @@ -98,18 +98,6 @@ static inline void arch_spin_lock_flags(arch_spinlock_t *lock, * read-locks. */ -/** - * read_can_lock - would read_trylock() succeed? - * @lock: the rwlock in question. - */ -#define arch_read_can_lock(x) ((int)(x)->lock > 0) - -/** - * write_can_lock - would write_trylock() succeed? - * @lock: the rwlock in question. - */ -#define arch_write_can_lock(x) ((x)->lock == RW_LOCK_BIAS) - /* * On mn10300, we implement read-write locks as a 32-bit counter * with the high bit (sign) being the "contended" bit. diff --git a/arch/parisc/include/asm/spinlock.h b/arch/parisc/include/asm/spinlock.h index 55bfe4a..136e1c9 100644 --- a/arch/parisc/include/asm/spinlock.h +++ b/arch/parisc/include/asm/spinlock.h @@ -168,24 +168,6 @@ static __inline__ int arch_write_trylock(arch_rwlock_t *rw) return result; } -/* - * read_can_lock - would read_trylock() succeed? - * @lock: the rwlock in question. - */ -static __inline__ int arch_read_can_lock(arch_rwlock_t *rw) -{ - return rw->counter >= 0; -} - -/* - * write_can_lock - would write_trylock() succeed? - * @lock: the rwlock in question. - */ -static __inline__ int arch_write_can_lock(arch_rwlock_t *rw) -{ - return !rw->counter; -} - #define arch_read_lock_flags(lock, flags) arch_read_lock(lock) #define arch_write_lock_flags(lock, flags) arch_write_lock(lock) diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h index edbe571..d83f4f7 100644 --- a/arch/powerpc/include/asm/spinlock.h +++ b/arch/powerpc/include/asm/spinlock.h @@ -181,9 +181,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) * read-locks. */ -#define arch_read_can_lock(rw) ((rw)->lock >= 0) -#define arch_write_can_lock(rw) (!(rw)->lock) - #ifdef CONFIG_PPC64 #define __DO_SIGN_EXTEND "extsw %0,%0\n" #define WRLOCK_TOKEN LOCK_TOKEN /* it's negative */ diff --git a/arch/s390/include/asm/spinlock.h b/arch/s390/include/asm/spinlock.h index 8182b52..dc9c58e 100644 --- a/arch/s390/include/asm/spinlock.h +++ b/arch/s390/include/asm/spinlock.h @@ -110,18 +110,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lp) * read-locks. */ -/** - * read_can_lock - would read_trylock() succeed? - * @lock: the rwlock in question. - */ -#define arch_read_can_lock(x) ((int)(x)->lock >= 0) - -/** - * write_can_lock - would write_trylock() succeed? - * @lock: the rwlock in question. - */ -#define arch_write_can_lock(x) ((x)->lock == 0) - extern int _raw_read_trylock_retry(arch_rwlock_t *lp); extern int _raw_write_trylock_retry(arch_rwlock_t *lp); diff --git a/arch/sh/include/asm/spinlock-cas.h b/arch/sh/include/asm/spinlock-cas.h index 5ed7dbb..3154678 100644 --- a/arch/sh/include/asm/spinlock-cas.h +++ b/arch/sh/include/asm/spinlock-cas.h @@ -53,18 +53,6 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock) * read-locks. */ -/** - * read_can_lock - would read_trylock() succeed? - * @lock: the rwlock in question. - */ -#define arch_read_can_lock(x) ((x)->lock > 0) - -/** - * write_can_lock - would write_trylock() succeed? - * @lock: the rwlock in question. - */ -#define arch_write_can_lock(x) ((x)->lock == RW_LOCK_BIAS) - static inline void arch_read_lock(arch_rwlock_t *rw) { unsigned old; diff --git a/arch/sh/include/asm/spinlock-llsc.h b/arch/sh/include/asm/spinlock-llsc.h index f77263a..06be4a5 100644 --- a/arch/sh/include/asm/spinlock-llsc.h +++ b/arch/sh/include/asm/spinlock-llsc.h @@ -89,18 +89,6 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock) * read-locks. */ -/** - * read_can_lock - would read_trylock() succeed? - * @lock: the rwlock in question. - */ -#define arch_read_can_lock(x) ((x)->lock > 0) - -/** - * write_can_lock - would write_trylock() succeed? - * @lock: the rwlock in question. - */ -#define arch_write_can_lock(x) ((x)->lock == RW_LOCK_BIAS) - static inline void arch_read_lock(arch_rwlock_t *rw) { unsigned long tmp; diff --git a/arch/sparc/include/asm/spinlock_32.h b/arch/sparc/include/asm/spinlock_32.h index 67345b2..76986b8 100644 --- a/arch/sparc/include/asm/spinlock_32.h +++ b/arch/sparc/include/asm/spinlock_32.h @@ -190,9 +190,6 @@ static inline int __arch_read_trylock(arch_rwlock_t *rw) #define arch_read_relax(lock) cpu_relax() #define arch_write_relax(lock) cpu_relax() -#define arch_read_can_lock(rw) (!((rw)->lock & 0xff)) -#define arch_write_can_lock(rw) (!(rw)->lock) - #endif /* !(__ASSEMBLY__) */ #endif /* __SPARC_SPINLOCK_H */ diff --git a/arch/tile/include/asm/spinlock_32.h b/arch/tile/include/asm/spinlock_32.h index cba8ba9..91d05f2 100644 --- a/arch/tile/include/asm/spinlock_32.h +++ b/arch/tile/include/asm/spinlock_32.h @@ -80,22 +80,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) #define _RD_COUNT_WIDTH 8 /** - * arch_read_can_lock() - would read_trylock() succeed? - */ -static inline int arch_read_can_lock(arch_rwlock_t *rwlock) -{ - return (rwlock->lock << _RD_COUNT_WIDTH) == 0; -} - -/** - * arch_write_can_lock() - would write_trylock() succeed? - */ -static inline int arch_write_can_lock(arch_rwlock_t *rwlock) -{ - return rwlock->lock == 0; -} - -/** * arch_read_lock() - acquire a read lock. */ void arch_read_lock(arch_rwlock_t *rwlock); diff --git a/arch/tile/include/asm/spinlock_64.h b/arch/tile/include/asm/spinlock_64.h index 9a2c2d6..c802f48b 100644 --- a/arch/tile/include/asm/spinlock_64.h +++ b/arch/tile/include/asm/spinlock_64.h @@ -93,24 +93,6 @@ static inline int arch_write_val_locked(int val) return val < 0; /* Optimize "val & __WRITE_LOCK_BIT". */ } -/** - * read_can_lock - would read_trylock() succeed? - * @lock: the rwlock in question. - */ -static inline int arch_read_can_lock(arch_rwlock_t *rw) -{ - return !arch_write_val_locked(rw->lock); -} - -/** - * write_can_lock - would write_trylock() succeed? - * @lock: the rwlock in question. - */ -static inline int arch_write_can_lock(arch_rwlock_t *rw) -{ - return rw->lock == 0; -} - extern void __read_lock_failed(arch_rwlock_t *rw); static inline void arch_read_lock(arch_rwlock_t *rw) diff --git a/arch/xtensa/include/asm/spinlock.h b/arch/xtensa/include/asm/spinlock.h index 3bb4968..d005af5 100644 --- a/arch/xtensa/include/asm/spinlock.h +++ b/arch/xtensa/include/asm/spinlock.h @@ -97,8 +97,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) * 0x80000000 one writer owns the rwlock, no other writers, no readers */ -#define arch_write_can_lock(x) ((x)->lock == 0) - static inline void arch_write_lock(arch_rwlock_t *rw) { unsigned long tmp; diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h index 7d026bf..5092532 100644 --- a/include/asm-generic/qrwlock.h +++ b/include/asm-generic/qrwlock.h @@ -53,24 +53,6 @@ extern void queued_read_lock_slowpath(struct qrwlock *lock, u32 cnts); extern void queued_write_lock_slowpath(struct qrwlock *lock); /** - * queued_read_can_lock- would read_trylock() succeed? - * @lock: Pointer to queue rwlock structure - */ -static inline int queued_read_can_lock(struct qrwlock *lock) -{ - return !(atomic_read(&lock->cnts) & _QW_WMASK); -} - -/** - * queued_write_can_lock- would write_trylock() succeed? - * @lock: Pointer to queue rwlock structure - */ -static inline int queued_write_can_lock(struct qrwlock *lock) -{ - return !atomic_read(&lock->cnts); -} - -/** * queued_read_trylock - try to acquire read lock of a queue rwlock * @lock : Pointer to queue rwlock structure * Return: 1 if lock acquired, 0 if failed @@ -169,8 +151,6 @@ static inline void queued_write_unlock(struct qrwlock *lock) * Remapping rwlock architecture specific functions to the corresponding * queue rwlock functions. */ -#define arch_read_can_lock(l) queued_read_can_lock(l) -#define arch_write_can_lock(l) queued_write_can_lock(l) #define arch_read_lock(l) queued_read_lock(l) #define arch_write_lock(l) queued_write_lock(l) #define arch_read_trylock(l) queued_read_trylock(l) diff --git a/include/linux/rwlock.h b/include/linux/rwlock.h index bc2994e..766c5ca 100644 --- a/include/linux/rwlock.h +++ b/include/linux/rwlock.h @@ -50,9 +50,6 @@ do { \ # define do_raw_write_unlock(rwlock) do {arch_write_unlock(&(rwlock)->raw_lock); __release(lock); } while (0) #endif -#define read_can_lock(rwlock) arch_read_can_lock(&(rwlock)->raw_lock) -#define write_can_lock(rwlock) arch_write_can_lock(&(rwlock)->raw_lock) - /* * Define the various rw_lock methods. Note we define these * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 69e079c..1e3e480 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -278,12 +278,6 @@ static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock) 1 : ({ local_irq_restore(flags); 0; }); \ }) -/** - * raw_spin_can_lock - would raw_spin_trylock() succeed? - * @lock: the spinlock in question. - */ -#define raw_spin_can_lock(lock) (!raw_spin_is_locked(lock)) - /* Include rwlock functions */ #include @@ -396,11 +390,6 @@ static __always_inline int spin_is_contended(spinlock_t *lock) return raw_spin_is_contended(&lock->rlock); } -static __always_inline int spin_can_lock(spinlock_t *lock) -{ - return raw_spin_can_lock(&lock->rlock); -} - #define assert_spin_locked(lock) assert_raw_spin_locked(&(lock)->rlock) /* diff --git a/include/linux/spinlock_up.h b/include/linux/spinlock_up.h index 612fb53..901cf8f 100644 --- a/include/linux/spinlock_up.h +++ b/include/linux/spinlock_up.h @@ -77,7 +77,4 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) #define arch_spin_is_contended(lock) (((void)(lock), 0)) -#define arch_read_can_lock(lock) (((void)(lock), 1)) -#define arch_write_can_lock(lock) (((void)(lock), 1)) - #endif /* __LINUX_SPINLOCK_UP_H */ diff --git a/kernel/locking/spinlock.c b/kernel/locking/spinlock.c index 4b082b5..8fd48b5 100644 --- a/kernel/locking/spinlock.c +++ b/kernel/locking/spinlock.c @@ -32,8 +32,6 @@ * include/linux/spinlock_api_smp.h */ #else -#define raw_read_can_lock(l) read_can_lock(l) -#define raw_write_can_lock(l) write_can_lock(l) /* * Some architectures can relax in favour of the CPU owning the lock. @@ -68,7 +66,7 @@ void __lockfunc __raw_##op##_lock(locktype##_t *lock) \ \ if (!(lock)->break_lock) \ (lock)->break_lock = 1; \ - while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\ + while ((lock)->break_lock) \ arch_##op##_relax(&lock->raw_lock); \ } \ (lock)->break_lock = 0; \ @@ -88,7 +86,7 @@ unsigned long __lockfunc __raw_##op##_lock_irqsave(locktype##_t *lock) \ \ if (!(lock)->break_lock) \ (lock)->break_lock = 1; \ - while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\ + while ((lock)->break_lock) \ arch_##op##_relax(&lock->raw_lock); \ } \ (lock)->break_lock = 0; \ -- cgit v1.1