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Atomic64 compatibility for 32-bit systems without kernel support.

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This patch is another step towards updating the code to handle the
32-bit kernels which I have not been regularly testing.  This changes
do not really impact the common case I'm expected which is the latest
kernel running on an x86_64 arch.

Until the linux-2.6.31 kernel the x86 arch did not have support for
64-bit atomic operations.  Additionally, the new atomic_compat.h support
for this case was wrong because it embedded a spinlock in the atomic
variable which must always and only be 64-bits total.  To handle these
32-bit issues we now simply fall back to the --enable-atomic-spinlock
implementation if the kernel does not provide the 64-bit atomic funcs.

The second issue this patch addresses is the DEBUG_KMEM assumption that
there will always be atomic64 funcs available.  On 32-bit archs this may
not be true, and actually that's just fine.  In that case the kernel will
will never be able to allocate more the 32-bits worth anyway.  So just
check if atomic64 funcs are available, if they are not it means this
is a 32-bit machine and we can safely use atomic_t's instead.
This commit is contained in:
Brian Behlendorf
2009-12-04 15:54:12 -08:00
parent db1aa22297
commit d04c8a563c
10 changed files with 396 additions and 788 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/sys/atomic.h
+8 -1
View File
@@ -30,7 +30,14 @@
#include <linux/module.h>
#include <linux/spinlock.h>
#include <sys/types.h>
#include <asm/atomic_compat.h>
#ifndef HAVE_ATOMIC64_CMPXCHG
#define atomic64_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
#endif
#ifndef HAVE_ATOMIC64_XCHG
#define atomic64_xchg(v, n) (xchg(&((v)->counter), n))
#endif
/*
* Two approaches to atomic operations are implemented each with its
include/sys/kmem.h
+29 -1
View File
@@ -41,7 +41,7 @@ extern "C" {
#include <linux/rwsem.h>
#include <linux/hash.h>
#include <linux/ctype.h>
#include <asm/atomic_compat.h>
#include <asm/atomic.h>
#include <sys/types.h>
#include <sys/debug.h>
#include <sys/vmsystm.h>
@@ -109,12 +109,40 @@ kmalloc_node_nofail(size_t size, gfp_t flags, int node)
#endif /* HAVE_KMALLOC_NODE */
#ifdef DEBUG_KMEM
# ifdef HAVE_ATOMIC64_T
extern atomic64_t kmem_alloc_used;
extern unsigned long long kmem_alloc_max;
extern atomic64_t vmem_alloc_used;
extern unsigned long long vmem_alloc_max;
# define kmem_alloc_used_add(size) atomic64_add(size, &kmem_alloc_used)
# define kmem_alloc_used_sub(size) atomic64_sub(size, &kmem_alloc_used)
# define kmem_alloc_used_read() atomic64_read(&kmem_alloc_used)
# define kmem_alloc_used_set(size) atomic64_set(&kmem_alloc_used, size)
# define vmem_alloc_used_add(size) atomic64_add(size, &vmem_alloc_used)
# define vmem_alloc_used_sub(size) atomic64_sub(size, &vmem_alloc_used)
# define vmem_alloc_used_read() atomic64_read(&vmem_alloc_used)
# define vmem_alloc_used_set(size) atomic64_set(&vmem_alloc_used, size)
# else
extern atomic_t kmem_alloc_used;
extern unsigned long long kmem_alloc_max;
extern atomic_t vmem_alloc_used;
extern unsigned long long vmem_alloc_max;
# define kmem_alloc_used_add(size) atomic_add(size, &kmem_alloc_used)
# define kmem_alloc_used_sub(size) atomic_sub(size, &kmem_alloc_used)
# define kmem_alloc_used_read() atomic_read(&kmem_alloc_used)
# define kmem_alloc_used_set(size) atomic_set(&kmem_alloc_used, size)
# define vmem_alloc_used_add(size) atomic_add(size, &vmem_alloc_used)
# define vmem_alloc_used_sub(size) atomic_sub(size, &vmem_alloc_used)
# define vmem_alloc_used_read() atomic_read(&vmem_alloc_used)
# define vmem_alloc_used_set(size) atomic_set(&vmem_alloc_used, size)
# endif /* _LP64 */
# define kmem_alloc(size, flags) __kmem_alloc((size), (flags), 0, 0)
# define kmem_zalloc(size, flags) __kmem_alloc((size), ((flags) | \
__GFP_ZERO), 0, 0)