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Message-Id: <1507041166-10618-2-git-send-email-will.deacon@arm.com>
Date: Tue, 3 Oct 2017 15:32:46 +0100
From: Will Deacon <will.deacon@....com>
To: linux-kernel@...r.kernel.org
Cc: john.johansen@...onical.com, paulmck@...ux.vnet.ibm.com,
Will Deacon <will.deacon@....com>,
Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH 2/2] locking: Remove {read,write}_can_lock
read_can_lock has no users in tree, and the last remaining user of
write_can_lock (apparmor) is moved over to lockdep by the previous path.
Remove the unused macros, since they don't work in a concurrent environment
and can give incorrect results for qrwlock.
Cc: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Will Deacon <will.deacon@....com>
---
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_up.h | 3 ---
kernel/locking/spinlock.c | 2 --
23 files changed, 240 deletions(-)
diff --git a/arch/alpha/include/asm/spinlock.h b/arch/alpha/include/asm/spinlock.h
index 718ac0b64adf..7bff6316b8bb 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 47efc8451b70..ce9bfcf1d870 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 c030143c18c6..f5223260c73e 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 f6431439d15d..607ef98c0f6c 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 53a8d5885887..9f9414b9c303 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 df2c121164b8..c728dda59bd2 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 a56825592b90..002601371b2f 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 ad8436feed8d..6a932a952d53 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 c630444cffe9..8ae12bfc8ad8 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 fe413b41df6c..54f75dac8094 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 55bfe4affca3..136e1c9bb8a9 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 edbe571bcc54..d83f4f755ad8 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 8182b521c42f..dc9c58ed9e4c 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 5ed7dbbd94ff..315467834521 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 f77263aae760..06be4a55f3c4 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 67345b2dc408..76986b8f7dad 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 cba8ba9b8da6..91d05f21cba9 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 9a2c2d605752..c802f48badf4 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 3bb49681ee24..d005af51e2e1 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 7d026bf27713..50925327b0a8 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 bc2994ed66e1..766c5ca5cbd1 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_up.h b/include/linux/spinlock_up.h
index 612fb530af41..901cf8f44388 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 4b082b5cac9e..42ee9d0a1ea4 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.
--
2.1.4
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