* [patch 1/8] bitops: introduce lock ops
2007-08-04 20:28 [patch 0/8] lock bitops and some bitops fixes Nick Piggin
@ 2007-08-04 20:28 ` Nick Piggin
2007-08-04 20:28 ` [patch 2/8] alpha: fix bitops Nick Piggin
` (6 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: Nick Piggin @ 2007-08-04 20:28 UTC (permalink / raw)
To: Andrew Morton; +Cc: Nick Piggin, Linux Arch
Introduce test_and_set_bit_lock / clear_bit_unlock bitops with lock semantics.
Convert all architectures to use the generic implementation.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-By: David Howells <dhowells@redhat.com>
---
Documentation/atomic_ops.txt | 14 +++++++++++
Documentation/memory-barriers.txt | 14 ++++++++++-
include/asm-alpha/bitops.h | 1
include/asm-arm/bitops.h | 1
include/asm-avr32/bitops.h | 1
include/asm-blackfin/bitops.h | 1
include/asm-cris/bitops.h | 1
include/asm-frv/bitops.h | 1
include/asm-generic/bitops.h | 1
include/asm-generic/bitops/lock.h | 45 ++++++++++++++++++++++++++++++++++++++
include/asm-h8300/bitops.h | 1
include/asm-i386/bitops.h | 1
include/asm-ia64/bitops.h | 2 +
include/asm-m32r/bitops.h | 1
include/asm-m68k/bitops.h | 1
include/asm-m68knommu/bitops.h | 1
include/asm-mips/bitops.h | 1
include/asm-parisc/bitops.h | 1
include/asm-powerpc/bitops.h | 1
include/asm-s390/bitops.h | 1
include/asm-sh/bitops.h | 1
include/asm-sh64/bitops.h | 1
include/asm-sparc/bitops.h | 1
include/asm-sparc64/bitops.h | 1
include/asm-v850/bitops.h | 1
include/asm-x86_64/bitops.h | 1
include/asm-xtensa/bitops.h | 1
27 files changed, 96 insertions(+), 2 deletions(-)
Index: linux-2.6/include/asm-alpha/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-alpha/bitops.h
+++ linux-2.6/include/asm-alpha/bitops.h
@@ -367,6 +367,7 @@ static inline unsigned int hweight8(unsi
#else
#include <asm-generic/bitops/hweight.h>
#endif
+#include <asm-generic/bitops/lock.h>
#endif /* __KERNEL__ */
Index: linux-2.6/include/asm-arm/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-arm/bitops.h
+++ linux-2.6/include/asm-arm/bitops.h
@@ -286,6 +286,7 @@ static inline int constant_fls(int x)
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
/*
* Ext2 is defined to use little-endian byte ordering.
Index: linux-2.6/include/asm-avr32/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-avr32/bitops.h
+++ linux-2.6/include/asm-avr32/bitops.h
@@ -288,6 +288,7 @@ static inline int ffs(unsigned long word
#include <asm-generic/bitops/fls64.h>
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/ext2-non-atomic.h>
#include <asm-generic/bitops/ext2-atomic.h>
Index: linux-2.6/include/asm-cris/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-cris/bitops.h
+++ linux-2.6/include/asm-cris/bitops.h
@@ -154,6 +154,7 @@ static inline int test_and_change_bit(in
#include <asm-generic/bitops/fls64.h>
#include <asm-generic/bitops/hweight.h>
#include <asm-generic/bitops/find.h>
+#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/ext2-non-atomic.h>
Index: linux-2.6/include/asm-frv/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-frv/bitops.h
+++ linux-2.6/include/asm-frv/bitops.h
@@ -302,6 +302,7 @@ int __ilog2_u64(u64 n)
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/ext2-non-atomic.h>
Index: linux-2.6/include/asm-generic/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-generic/bitops.h
+++ linux-2.6/include/asm-generic/bitops.h
@@ -22,6 +22,7 @@
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/ffs.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/ext2-non-atomic.h>
#include <asm-generic/bitops/ext2-atomic.h>
Index: linux-2.6/include/asm-generic/bitops/lock.h
===================================================================
--- /dev/null
+++ linux-2.6/include/asm-generic/bitops/lock.h
@@ -0,0 +1,45 @@
+#ifndef _ASM_GENERIC_BITOPS_LOCK_H_
+#define _ASM_GENERIC_BITOPS_LOCK_H_
+
+/**
+ * test_and_set_bit_lock - Set a bit and return its old value, for lock
+ * @nr: Bit to set
+ * @addr: Address to count from
+ *
+ * This operation is atomic and provides acquire barrier semantics.
+ * It can be used to implement bit locks.
+ */
+#define test_and_set_bit_lock(nr, addr) test_and_set_bit(nr, addr)
+
+/**
+ * clear_bit_unlock - Clear a bit in memory, for unlock
+ * @nr: the bit to set
+ * @addr: the address to start counting from
+ *
+ * This operation is atomic and provides release barrier semantics.
+ */
+#define clear_bit_unlock(nr, addr) \
+do { \
+ smp_mb__before_clear_bit(); \
+ clear_bit(nr, addr); \
+} while (0)
+
+/**
+ * __clear_bit_unlock - Clear a bit in memory, for unlock
+ * @nr: the bit to set
+ * @addr: the address to start counting from
+ *
+ * This operation is like clear_bit_unlock, however it is not atomic.
+ * It does provide release barrier semantics so it can be used to unlock
+ * a bit lock, however it would only be used if no other CPU can modify
+ * any bits in the memory until the lock is released (a good example is
+ * if the bit lock itself protects access to the other bits in the word).
+ */
+#define __clear_bit_unlock(nr, addr) \
+do { \
+ smp_mb(); \
+ __clear_bit(nr, addr); \
+} while (0)
+
+#endif /* _ASM_GENERIC_BITOPS_LOCK_H_ */
+
Index: linux-2.6/include/asm-h8300/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-h8300/bitops.h
+++ linux-2.6/include/asm-h8300/bitops.h
@@ -194,6 +194,7 @@ static __inline__ unsigned long __ffs(un
#include <asm-generic/bitops/find.h>
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/ext2-non-atomic.h>
#include <asm-generic/bitops/ext2-atomic.h>
#include <asm-generic/bitops/minix.h>
Index: linux-2.6/include/asm-i386/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-i386/bitops.h
+++ linux-2.6/include/asm-i386/bitops.h
@@ -402,6 +402,7 @@ static inline int fls(int x)
}
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#endif /* __KERNEL__ */
Index: linux-2.6/include/asm-m32r/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-m32r/bitops.h
+++ linux-2.6/include/asm-m32r/bitops.h
@@ -255,6 +255,7 @@ static __inline__ int test_and_change_bi
#include <asm-generic/bitops/find.h>
#include <asm-generic/bitops/ffs.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#endif /* __KERNEL__ */
Index: linux-2.6/include/asm-m68k/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-m68k/bitops.h
+++ linux-2.6/include/asm-m68k/bitops.h
@@ -314,6 +314,7 @@ static inline int fls(int x)
#include <asm-generic/bitops/fls64.h>
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
/* Bitmap functions for the minix filesystem */
Index: linux-2.6/include/asm-m68knommu/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-m68knommu/bitops.h
+++ linux-2.6/include/asm-m68knommu/bitops.h
@@ -160,6 +160,7 @@ static __inline__ int __test_bit(int nr,
#include <asm-generic/bitops/find.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
static __inline__ int ext2_set_bit(int nr, volatile void * addr)
{
Index: linux-2.6/include/asm-mips/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-mips/bitops.h
+++ linux-2.6/include/asm-mips/bitops.h
@@ -556,6 +556,7 @@ static inline int ffs(int word)
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/ext2-non-atomic.h>
#include <asm-generic/bitops/ext2-atomic.h>
#include <asm-generic/bitops/minix.h>
Index: linux-2.6/include/asm-parisc/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-parisc/bitops.h
+++ linux-2.6/include/asm-parisc/bitops.h
@@ -208,6 +208,7 @@ static __inline__ int fls(int x)
#include <asm-generic/bitops/fls64.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/sched.h>
#endif /* __KERNEL__ */
Index: linux-2.6/include/asm-s390/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-s390/bitops.h
+++ linux-2.6/include/asm-s390/bitops.h
@@ -746,6 +746,7 @@ static inline int sched_find_first_bit(u
#include <asm-generic/bitops/fls64.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
/*
* ATTENTION: intel byte ordering convention for ext2 and minix !!
Index: linux-2.6/include/asm-sh/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-sh/bitops.h
+++ linux-2.6/include/asm-sh/bitops.h
@@ -137,6 +137,7 @@ static inline unsigned long __ffs(unsign
#include <asm-generic/bitops/find.h>
#include <asm-generic/bitops/ffs.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/ext2-non-atomic.h>
#include <asm-generic/bitops/ext2-atomic.h>
Index: linux-2.6/include/asm-sh64/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-sh64/bitops.h
+++ linux-2.6/include/asm-sh64/bitops.h
@@ -136,6 +136,7 @@ static __inline__ unsigned long ffz(unsi
#include <asm-generic/bitops/__ffs.h>
#include <asm-generic/bitops/find.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/ffs.h>
#include <asm-generic/bitops/ext2-non-atomic.h>
Index: linux-2.6/include/asm-sparc/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-sparc/bitops.h
+++ linux-2.6/include/asm-sparc/bitops.h
@@ -96,6 +96,7 @@ static inline void change_bit(unsigned l
#include <asm-generic/bitops/fls.h>
#include <asm-generic/bitops/fls64.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/find.h>
#include <asm-generic/bitops/ext2-non-atomic.h>
#include <asm-generic/bitops/ext2-atomic.h>
Index: linux-2.6/include/asm-sparc64/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-sparc64/bitops.h
+++ linux-2.6/include/asm-sparc64/bitops.h
@@ -81,6 +81,7 @@ static inline unsigned int hweight8(unsi
#include <asm-generic/bitops/hweight.h>
#endif
+#include <asm-generic/bitops/lock.h>
#endif /* __KERNEL__ */
#include <asm-generic/bitops/find.h>
Index: linux-2.6/include/asm-v850/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-v850/bitops.h
+++ linux-2.6/include/asm-v850/bitops.h
@@ -145,6 +145,7 @@ static inline int __test_bit (int nr, co
#include <asm-generic/bitops/find.h>
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/ext2-non-atomic.h>
#define ext2_set_bit_atomic(l,n,a) test_and_set_bit(n,a)
Index: linux-2.6/include/asm-xtensa/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-xtensa/bitops.h
+++ linux-2.6/include/asm-xtensa/bitops.h
@@ -108,6 +108,7 @@ static inline int fls (unsigned int x)
#endif
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/minix.h>
Index: linux-2.6/Documentation/atomic_ops.txt
===================================================================
--- linux-2.6.orig/Documentation/atomic_ops.txt
+++ linux-2.6/Documentation/atomic_ops.txt
@@ -369,6 +369,20 @@ brothers:
*/
smp_mb__after_clear_bit();
+There are two special bitops with lock barrier semantics (acquire/release,
+same as spinlocks). These operate in the same way as their non-_lock/unlock
+postfixed variants, except that they are to provide acquire/release semantics,
+respectively. This means they can be used for bit_spin_trylock and
+bit_spin_unlock type operations without specifying any more barriers.
+
+ int test_and_set_bit_lock(unsigned long nr, unsigned long *addr);
+ void clear_bit_unlock(unsigned long nr, unsigned long *addr);
+ void __clear_bit_unlock(unsigned long nr, unsigned long *addr);
+
+The __clear_bit_unlock version is non-atomic, however it still implements
+unlock barrier semantics. This can be useful if the lock itself is protecting
+the other bits in the word.
+
Finally, there are non-atomic versions of the bitmask operations
provided. They are used in contexts where some other higher-level SMP
locking scheme is being used to protect the bitmask, and thus less
Index: linux-2.6/Documentation/memory-barriers.txt
===================================================================
--- linux-2.6.orig/Documentation/memory-barriers.txt
+++ linux-2.6/Documentation/memory-barriers.txt
@@ -1479,7 +1479,8 @@ kernel.
Any atomic operation that modifies some state in memory and returns information
about the state (old or new) implies an SMP-conditional general memory barrier
-(smp_mb()) on each side of the actual operation. These include:
+(smp_mb()) on each side of the actual operation (with the exception of
+explicit lock operations, described later). These include:
xchg();
cmpxchg();
@@ -1536,10 +1537,19 @@ If they're used for constructing a lock
do need memory barriers as a lock primitive generally has to do things in a
specific order.
-
Basically, each usage case has to be carefully considered as to whether memory
barriers are needed or not.
+The following operations are special locking primitives:
+
+ test_and_set_bit_lock();
+ clear_bit_unlock();
+ __clear_bit_unlock();
+
+These implement LOCK-class and UNLOCK-class operations. These should be used in
+preference to other operations when implementing locking primitives, because
+their implementations can be optimised on many architectures.
+
[!] Note that special memory barrier primitives are available for these
situations because on some CPUs the atomic instructions used imply full memory
barriers, and so barrier instructions are superfluous in conjunction with them,
Index: linux-2.6/include/asm-blackfin/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-blackfin/bitops.h
+++ linux-2.6/include/asm-blackfin/bitops.h
@@ -199,6 +199,7 @@ static __inline__ int __test_bit(int nr,
#include <asm-generic/bitops/find.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/ext2-atomic.h>
#include <asm-generic/bitops/ext2-non-atomic.h>
Index: linux-2.6/include/asm-x86_64/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-x86_64/bitops.h
+++ linux-2.6/include/asm-x86_64/bitops.h
@@ -408,6 +408,7 @@ static __inline__ int fls(int x)
#define ARCH_HAS_FAST_MULTIPLIER 1
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#endif /* __KERNEL__ */
Index: linux-2.6/include/asm-ia64/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-ia64/bitops.h
+++ linux-2.6/include/asm-ia64/bitops.h
@@ -371,6 +371,8 @@ hweight64 (unsigned long x)
#define hweight16(x) (unsigned int) hweight64((x) & 0xfffful)
#define hweight8(x) (unsigned int) hweight64((x) & 0xfful)
+#include <asm-generic/bitops/lock.h>
+
#endif /* __KERNEL__ */
#include <asm-generic/bitops/find.h>
Index: linux-2.6/include/asm-powerpc/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-powerpc/bitops.h
+++ linux-2.6/include/asm-powerpc/bitops.h
@@ -266,6 +266,7 @@ static __inline__ int fls(unsigned int x
#include <asm-generic/bitops/fls64.h>
#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/lock.h>
#define find_first_zero_bit(addr, size) find_next_zero_bit((addr), (size), 0)
unsigned long find_next_zero_bit(const unsigned long *addr,
^ permalink raw reply [flat|nested] 10+ messages in thread* [patch 2/8] alpha: fix bitops
2007-08-04 20:28 [patch 0/8] lock bitops and some bitops fixes Nick Piggin
2007-08-04 20:28 ` [patch 1/8] bitops: introduce lock ops Nick Piggin
@ 2007-08-04 20:28 ` Nick Piggin
2007-08-04 20:28 ` [patch 3/8] alpha: lock bitops Nick Piggin
` (5 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: Nick Piggin @ 2007-08-04 20:28 UTC (permalink / raw)
To: Andrew Morton; +Cc: Nick Piggin, Linux Arch
Documentation/atomic_ops.txt defines these primitives must contain a memory
barrier both before and after their memory operation. This is consistent with
the atomic ops implementation on alpha.
Signed-off-by: Nick Piggin <npiggin@suse.de>
---
include/asm-alpha/bitops.h | 9 +++++++++
1 file changed, 9 insertions(+)
Index: linux-2.6/include/asm-alpha/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-alpha/bitops.h
+++ linux-2.6/include/asm-alpha/bitops.h
@@ -117,6 +117,9 @@ test_and_set_bit(unsigned long nr, volat
int *m = ((int *) addr) + (nr >> 5);
__asm__ __volatile__(
+#ifdef CONFIG_SMP
+ " mb\n"
+#endif
"1: ldl_l %0,%4\n"
" and %0,%3,%2\n"
" bne %2,2f\n"
@@ -158,6 +161,9 @@ test_and_clear_bit(unsigned long nr, vol
int *m = ((int *) addr) + (nr >> 5);
__asm__ __volatile__(
+#ifdef CONFIG_SMP
+ " mb\n"
+#endif
"1: ldl_l %0,%4\n"
" and %0,%3,%2\n"
" beq %2,2f\n"
@@ -199,6 +205,9 @@ test_and_change_bit(unsigned long nr, vo
int *m = ((int *) addr) + (nr >> 5);
__asm__ __volatile__(
+#ifdef CONFIG_SMP
+ " mb\n"
+#endif
"1: ldl_l %0,%4\n"
" and %0,%3,%2\n"
" xor %0,%3,%0\n"
^ permalink raw reply [flat|nested] 10+ messages in thread* [patch 3/8] alpha: lock bitops
2007-08-04 20:28 [patch 0/8] lock bitops and some bitops fixes Nick Piggin
2007-08-04 20:28 ` [patch 1/8] bitops: introduce lock ops Nick Piggin
2007-08-04 20:28 ` [patch 2/8] alpha: fix bitops Nick Piggin
@ 2007-08-04 20:28 ` Nick Piggin
2007-08-04 20:28 ` [patch 4/8] ia64: " Nick Piggin
` (4 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: Nick Piggin @ 2007-08-04 20:28 UTC (permalink / raw)
To: Andrew Morton; +Cc: Nick Piggin, Linux Arch
Alpha can avoid one mb when acquiring a lock with test_and_set_bit_lock.
Signed-off-by: Nick Piggin <npiggin@suse.de>
---
include/asm-alpha/bitops.h | 42 +++++++++++++++++++++++++++++++++++++++++-
1 file changed, 41 insertions(+), 1 deletion(-)
Index: linux-2.6/include/asm-alpha/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-alpha/bitops.h
+++ linux-2.6/include/asm-alpha/bitops.h
@@ -69,6 +69,13 @@ clear_bit(unsigned long nr, volatile voi
:"Ir" (1UL << (nr & 31)), "m" (*m));
}
+static inline void
+clear_bit_unlock(unsigned long nr, volatile void * addr)
+{
+ smp_mb();
+ clear_bit(nr, addr);
+}
+
/*
* WARNING: non atomic version.
*/
@@ -81,6 +88,13 @@ __clear_bit(unsigned long nr, volatile v
}
static inline void
+__clear_bit_unlock(unsigned long nr, volatile void * addr)
+{
+ smp_mb();
+ __clear_bit(nr, addr);
+}
+
+static inline void
change_bit(unsigned long nr, volatile void * addr)
{
unsigned long temp;
@@ -139,6 +153,33 @@ test_and_set_bit(unsigned long nr, volat
return oldbit != 0;
}
+static inline int
+test_and_set_bit_lock(unsigned long nr, volatile void *addr)
+{
+ unsigned long oldbit;
+ unsigned long temp;
+ int *m = ((int *) addr) + (nr >> 5);
+
+ __asm__ __volatile__(
+ "1: ldl_l %0,%4\n"
+ " and %0,%3,%2\n"
+ " bne %2,2f\n"
+ " xor %0,%3,%0\n"
+ " stl_c %0,%1\n"
+ " beq %0,3f\n"
+ "2:\n"
+#ifdef CONFIG_SMP
+ " mb\n"
+#endif
+ ".subsection 2\n"
+ "3: br 1b\n"
+ ".previous"
+ :"=&r" (temp), "=m" (*m), "=&r" (oldbit)
+ :"Ir" (1UL << (nr & 31)), "m" (*m) : "memory");
+
+ return oldbit != 0;
+}
+
/*
* WARNING: non atomic version.
*/
@@ -376,7 +417,6 @@ static inline unsigned int hweight8(unsi
#else
#include <asm-generic/bitops/hweight.h>
#endif
-#include <asm-generic/bitops/lock.h>
#endif /* __KERNEL__ */
^ permalink raw reply [flat|nested] 10+ messages in thread* [patch 4/8] ia64: lock bitops
2007-08-04 20:28 [patch 0/8] lock bitops and some bitops fixes Nick Piggin
` (2 preceding siblings ...)
2007-08-04 20:28 ` [patch 3/8] alpha: lock bitops Nick Piggin
@ 2007-08-04 20:28 ` Nick Piggin
2007-08-04 20:29 ` [patch 5/8] mips: fix bitops Nick Piggin
` (3 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: Nick Piggin @ 2007-08-04 20:28 UTC (permalink / raw)
To: Andrew Morton; +Cc: Nick Piggin, Linux Arch
Convert ia64 to new bitops.
Signed-off-by: Nick Piggin <npiggin@suse.de>
---
include/asm-ia64/bitops.h | 43 +++++++++++++++++++++++++++++++++++++++++--
1 file changed, 41 insertions(+), 2 deletions(-)
Index: linux-2.6/include/asm-ia64/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-ia64/bitops.h
+++ linux-2.6/include/asm-ia64/bitops.h
@@ -94,6 +94,38 @@ clear_bit (int nr, volatile void *addr)
}
/**
+ * clear_bit_unlock - Clears a bit in memory with release
+ * @nr: Bit to clear
+ * @addr: Address to start counting from
+ *
+ * clear_bit_unlock() is atomic and may not be reordered. It does
+ * contain a memory barrier suitable for unlock type operations.
+ */
+static __inline__ void
+clear_bit_unlock (int nr, volatile void *addr)
+{
+ __u32 mask, old, new;
+ volatile __u32 *m;
+ CMPXCHG_BUGCHECK_DECL
+
+ m = (volatile __u32 *) addr + (nr >> 5);
+ mask = ~(1 << (nr & 31));
+ do {
+ CMPXCHG_BUGCHECK(m);
+ old = *m;
+ new = old & mask;
+ } while (cmpxchg_rel(m, old, new) != old);
+}
+
+/**
+ * __clear_bit_unlock - Non-atomically clear a bit with release
+ *
+ * This is like clear_bit_unlock, but the implementation may use a non-atomic
+ * store (this one uses an atomic, however).
+ */
+#define __clear_bit_unlock clear_bit_unlock
+
+/**
* __clear_bit - Clears a bit in memory (non-atomic version)
*/
static __inline__ void
@@ -170,6 +202,15 @@ test_and_set_bit (int nr, volatile void
}
/**
+ * test_and_set_bit_lock - Set a bit and return its old value for lock
+ * @nr: Bit to set
+ * @addr: Address to count from
+ *
+ * This is the same as test_and_set_bit on ia64
+ */
+#define test_and_set_bit_lock test_and_set_bit
+
+/**
* __test_and_set_bit - Set a bit and return its old value
* @nr: Bit to set
* @addr: Address to count from
@@ -371,8 +412,6 @@ hweight64 (unsigned long x)
#define hweight16(x) (unsigned int) hweight64((x) & 0xfffful)
#define hweight8(x) (unsigned int) hweight64((x) & 0xfful)
-#include <asm-generic/bitops/lock.h>
-
#endif /* __KERNEL__ */
#include <asm-generic/bitops/find.h>
^ permalink raw reply [flat|nested] 10+ messages in thread* [patch 5/8] mips: fix bitops
2007-08-04 20:28 [patch 0/8] lock bitops and some bitops fixes Nick Piggin
` (3 preceding siblings ...)
2007-08-04 20:28 ` [patch 4/8] ia64: " Nick Piggin
@ 2007-08-04 20:29 ` Nick Piggin
2007-08-04 20:29 ` [patch 6/8] mips: lock bitops Nick Piggin
` (2 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: Nick Piggin @ 2007-08-04 20:29 UTC (permalink / raw)
To: Andrew Morton; +Cc: Nick Piggin, Linux Arch
Documentation/atomic_ops.txt defines these primitives must contain a memory
barrier both before and after their memory operation. This is consistent with
the atomic ops implementation on mips.
Signed-off-by: Nick Piggin <npiggin@suse.de>
---
include/asm-mips/bitops.h | 6 ++++++
1 file changed, 6 insertions(+)
Index: linux-2.6/include/asm-mips/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-mips/bitops.h
+++ linux-2.6/include/asm-mips/bitops.h
@@ -240,6 +240,8 @@ static inline int test_and_set_bit(unsig
unsigned short bit = nr & SZLONG_MASK;
unsigned long res;
+ smp_llsc_mb();
+
if (cpu_has_llsc && R10000_LLSC_WAR) {
unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
unsigned long temp;
@@ -308,6 +310,8 @@ static inline int test_and_clear_bit(uns
unsigned short bit = nr & SZLONG_MASK;
unsigned long res;
+ smp_llsc_mb();
+
if (cpu_has_llsc && R10000_LLSC_WAR) {
unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
unsigned long temp;
@@ -396,6 +400,8 @@ static inline int test_and_change_bit(un
unsigned short bit = nr & SZLONG_MASK;
unsigned long res;
+ smp_llsc_mb();
+
if (cpu_has_llsc && R10000_LLSC_WAR) {
unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
unsigned long temp;
^ permalink raw reply [flat|nested] 10+ messages in thread* [patch 6/8] mips: lock bitops
2007-08-04 20:28 [patch 0/8] lock bitops and some bitops fixes Nick Piggin
` (4 preceding siblings ...)
2007-08-04 20:29 ` [patch 5/8] mips: fix bitops Nick Piggin
@ 2007-08-04 20:29 ` Nick Piggin
2007-08-04 20:29 ` [patch 7/8] powerpc: " Nick Piggin
2007-08-04 20:29 ` [patch 8/8] bit_spin_lock: use " Nick Piggin
7 siblings, 0 replies; 10+ messages in thread
From: Nick Piggin @ 2007-08-04 20:29 UTC (permalink / raw)
To: Andrew Morton; +Cc: Nick Piggin, Linux Arch
mips can avoid one mb when acquiring a lock with test_and_set_bit_lock.
Signed-off-by: Nick Piggin <npiggin@suse.de>
--
---
include/asm-mips/bitops.h | 97 +++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 96 insertions(+), 1 deletion(-)
Index: linux-2.6/include/asm-mips/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-mips/bitops.h
+++ linux-2.6/include/asm-mips/bitops.h
@@ -172,6 +172,20 @@ static inline void clear_bit(unsigned lo
}
/*
+ * clear_bit_unlock - Clears a bit in memory
+ * @nr: Bit to clear
+ * @addr: Address to start counting from
+ *
+ * clear_bit() is atomic and implies release semantics before the memory
+ * operation. It can be used for an unlock.
+ */
+static inline void clear_bit_unlock(unsigned long nr, volatile unsigned long *addr)
+{
+ smp_mb__before_clear_bit();
+ clear_bit(nr, addr);
+}
+
+/*
* change_bit - Toggle a bit in memory
* @nr: Bit to change
* @addr: Address to start counting from
@@ -297,6 +311,73 @@ static inline int test_and_set_bit(unsig
}
/*
+ * test_and_set_bit_lock - Set a bit and return its old value
+ * @nr: Bit to set
+ * @addr: Address to count from
+ *
+ * This operation is atomic and implies acquire ordering semantics
+ * after the memory operation.
+ */
+static inline int test_and_set_bit_lock(unsigned long nr,
+ volatile unsigned long *addr)
+{
+ unsigned short bit = nr & SZLONG_MASK;
+ unsigned long res;
+
+ if (cpu_has_llsc && R10000_LLSC_WAR) {
+ unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
+ unsigned long temp;
+
+ __asm__ __volatile__(
+ " .set mips3 \n"
+ "1: " __LL "%0, %1 # test_and_set_bit \n"
+ " or %2, %0, %3 \n"
+ " " __SC "%2, %1 \n"
+ " beqzl %2, 1b \n"
+ " and %2, %0, %3 \n"
+ " .set mips0 \n"
+ : "=&r" (temp), "=m" (*m), "=&r" (res)
+ : "r" (1UL << bit), "m" (*m)
+ : "memory");
+ } else if (cpu_has_llsc) {
+ unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
+ unsigned long temp;
+
+ __asm__ __volatile__(
+ " .set push \n"
+ " .set noreorder \n"
+ " .set mips3 \n"
+ "1: " __LL "%0, %1 # test_and_set_bit \n"
+ " or %2, %0, %3 \n"
+ " " __SC "%2, %1 \n"
+ " beqz %2, 2f \n"
+ " and %2, %0, %3 \n"
+ " .subsection 2 \n"
+ "2: b 1b \n"
+ " nop \n"
+ " .previous \n"
+ " .set pop \n"
+ : "=&r" (temp), "=m" (*m), "=&r" (res)
+ : "r" (1UL << bit), "m" (*m)
+ : "memory");
+ } else {
+ volatile unsigned long *a = addr;
+ unsigned long mask;
+ unsigned long flags;
+
+ a += nr >> SZLONG_LOG;
+ mask = 1UL << bit;
+ raw_local_irq_save(flags);
+ res = (mask & *a);
+ *a |= mask;
+ raw_local_irq_restore(flags);
+ }
+
+ smp_llsc_mb();
+
+ return res != 0;
+}
+/*
* test_and_clear_bit - Clear a bit and return its old value
* @nr: Bit to clear
* @addr: Address to count from
@@ -459,6 +540,21 @@ static inline int test_and_change_bit(un
#include <asm-generic/bitops/non-atomic.h>
/*
+ * __clear_bit_unlock - Clears a bit in memory
+ * @nr: Bit to clear
+ * @addr: Address to start counting from
+ *
+ * __clear_bit() is non-atomic and implies release semantics before the memory
+ * operation. It can be used for an unlock if no other CPUs can concurrently
+ * modify other bits in the word.
+ */
+static inline void __clear_bit_unlock(unsigned long nr, volatile unsigned long *addr)
+{
+ smp_mb();
+ __clear_bit(nr, addr);
+}
+
+/*
* Return the bit position (0..63) of the most significant 1 bit in a word
* Returns -1 if no 1 bit exists
*/
@@ -562,7 +658,6 @@ static inline int ffs(int word)
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/hweight.h>
-#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/ext2-non-atomic.h>
#include <asm-generic/bitops/ext2-atomic.h>
#include <asm-generic/bitops/minix.h>
^ permalink raw reply [flat|nested] 10+ messages in thread* [patch 7/8] powerpc: lock bitops
2007-08-04 20:28 [patch 0/8] lock bitops and some bitops fixes Nick Piggin
` (5 preceding siblings ...)
2007-08-04 20:29 ` [patch 6/8] mips: lock bitops Nick Piggin
@ 2007-08-04 20:29 ` Nick Piggin
2007-08-04 20:29 ` [patch 8/8] bit_spin_lock: use " Nick Piggin
7 siblings, 0 replies; 10+ messages in thread
From: Nick Piggin @ 2007-08-04 20:29 UTC (permalink / raw)
To: Andrew Morton; +Cc: Nick Piggin, Linux Arch
Add non-trivial lock bitops implementation for powerpc.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
include/asm-powerpc/bitops.h | 46 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 45 insertions(+), 1 deletion(-)
Index: linux-2.6/include/asm-powerpc/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-powerpc/bitops.h
+++ linux-2.6/include/asm-powerpc/bitops.h
@@ -86,6 +86,24 @@ static __inline__ void clear_bit(int nr,
: "cc" );
}
+static __inline__ void clear_bit_unlock(int nr, volatile unsigned long *addr)
+{
+ unsigned long old;
+ unsigned long mask = BITOP_MASK(nr);
+ unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
+
+ __asm__ __volatile__(
+ LWSYNC_ON_SMP
+"1:" PPC_LLARX "%0,0,%3 # clear_bit_unlock\n"
+ "andc %0,%0,%2\n"
+ PPC405_ERR77(0,%3)
+ PPC_STLCX "%0,0,%3\n"
+ "bne- 1b"
+ : "=&r" (old), "+m" (*p)
+ : "r" (mask), "r" (p)
+ : "cc", "memory");
+}
+
static __inline__ void change_bit(int nr, volatile unsigned long *addr)
{
unsigned long old;
@@ -125,6 +143,27 @@ static __inline__ int test_and_set_bit(u
return (old & mask) != 0;
}
+static __inline__ int test_and_set_bit_lock(unsigned long nr,
+ volatile unsigned long *addr)
+{
+ unsigned long old, t;
+ unsigned long mask = BITOP_MASK(nr);
+ unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
+
+ __asm__ __volatile__(
+"1:" PPC_LLARX "%0,0,%3 # test_and_set_bit_lock\n"
+ "or %1,%0,%2 \n"
+ PPC405_ERR77(0,%3)
+ PPC_STLCX "%1,0,%3 \n"
+ "bne- 1b"
+ ISYNC_ON_SMP
+ : "=&r" (old), "=&r" (t)
+ : "r" (mask), "r" (p)
+ : "cc", "memory");
+
+ return (old & mask) != 0;
+}
+
static __inline__ int test_and_clear_bit(unsigned long nr,
volatile unsigned long *addr)
{
@@ -185,6 +224,12 @@ static __inline__ void set_bits(unsigned
#include <asm-generic/bitops/non-atomic.h>
+static __inline__ void __clear_bit_unlock(int nr, volatile unsigned long *addr)
+{
+ __asm__ __volatile__(LWSYNC_ON_SMP ::: "memory");
+ __clear_bit(nr, addr);
+}
+
/*
* Return the zero-based bit position (LE, not IBM bit numbering) of
* the most significant 1-bit in a double word.
@@ -266,7 +311,6 @@ static __inline__ int fls(unsigned int x
#include <asm-generic/bitops/fls64.h>
#include <asm-generic/bitops/hweight.h>
-#include <asm-generic/bitops/lock.h>
#define find_first_zero_bit(addr, size) find_next_zero_bit((addr), (size), 0)
unsigned long find_next_zero_bit(const unsigned long *addr,
^ permalink raw reply [flat|nested] 10+ messages in thread* [patch 8/8] bit_spin_lock: use lock bitops
2007-08-04 20:28 [patch 0/8] lock bitops and some bitops fixes Nick Piggin
` (6 preceding siblings ...)
2007-08-04 20:29 ` [patch 7/8] powerpc: " Nick Piggin
@ 2007-08-04 20:29 ` Nick Piggin
7 siblings, 0 replies; 10+ messages in thread
From: Nick Piggin @ 2007-08-04 20:29 UTC (permalink / raw)
To: Andrew Morton; +Cc: Nick Piggin, Linux Arch
Convert bit_spin_lock to new locking bitops. Slub can use the non-atomic store
version to clear (Christoph?)
Signed-off-by: Nick Piggin <npiggin@suse.de>
---
include/linux/bit_spinlock.h | 26 ++++++++++++++++++++++----
1 file changed, 22 insertions(+), 4 deletions(-)
Index: linux-2.6/include/linux/bit_spinlock.h
===================================================================
--- linux-2.6.orig/include/linux/bit_spinlock.h
+++ linux-2.6/include/linux/bit_spinlock.h
@@ -18,7 +18,7 @@ static inline void bit_spin_lock(int bit
*/
preempt_disable();
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
- while (test_and_set_bit(bitnum, addr)) {
+ while (unlikely(test_and_set_bit_lock(bitnum, addr))) {
while (test_bit(bitnum, addr)) {
preempt_enable();
cpu_relax();
@@ -36,7 +36,7 @@ static inline int bit_spin_trylock(int b
{
preempt_disable();
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
- if (test_and_set_bit(bitnum, addr)) {
+ if (unlikely(test_and_set_bit_lock(bitnum, addr))) {
preempt_enable();
return 0;
}
@@ -50,10 +50,28 @@ static inline int bit_spin_trylock(int b
*/
static 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 inline void __bit_spin_unlock(int bitnum, unsigned long *addr)
+{
+#ifdef CONFIG_DEBUG_SPINLOCK
BUG_ON(!test_bit(bitnum, addr));
- smp_mb__before_clear_bit();
- clear_bit(bitnum, addr);
+#endif
+#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
+ __clear_bit_unlock(bitnum, addr);
#endif
preempt_enable();
__release(bitlock);
^ permalink raw reply [flat|nested] 10+ messages in thread