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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-virtio

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* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-virtio:
  virtio: Force use of power-of-two for descriptor ring sizes
  lguest: Fix lguest virtio-blk backend size computation
  virtio: Fix used_idx wrap-around
  virtio: more fallout from scatterlist changes.
  virtio: fix vring_init for 64 bits
This commit is contained in:
Linus Torvalds
2007-11-12 11:13:31 -08:00
parent e697b8d13e 42b36cc0ce
commit 05f3f41589
5 changed files with 34 additions and 20 deletions
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include/linux/virtio_ring.h
+12 -9
View File
@@ -67,7 +67,7 @@ struct vring {
};
/* The standard layout for the ring is a continuous chunk of memory which looks
* like this. The used fields will be aligned to a "num+1" boundary.
* like this. We assume num is a power of 2.
*
* struct vring
* {
@@ -79,8 +79,8 @@ struct vring {
* __u16 avail_idx;
* __u16 available[num];
*
* // Padding so a correctly-chosen num value will cache-align used_idx.
* char pad[sizeof(struct vring_desc) - sizeof(avail_flags)];
* // Padding to the next page boundary.
* char pad[];
*
* // A ring of used descriptor heads with free-running index.
* __u16 used_flags;
@@ -88,18 +88,21 @@ struct vring {
* struct vring_used_elem used[num];
* };
*/
static inline void vring_init(struct vring *vr, unsigned int num, void *p)
static inline void vring_init(struct vring *vr, unsigned int num, void *p,
unsigned int pagesize)
{
vr->num = num;
vr->desc = p;
vr->avail = p + num*sizeof(struct vring);
vr->used = p + (num+1)*(sizeof(struct vring) + sizeof(__u16));
vr->avail = p + num*sizeof(struct vring_desc);
vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + pagesize-1)
& ~(pagesize - 1));
}
static inline unsigned vring_size(unsigned int num)
static inline unsigned vring_size(unsigned int num, unsigned int pagesize)
{
return (num + 1) * (sizeof(struct vring_desc) + sizeof(__u16))
+ sizeof(__u32) + num * sizeof(struct vring_used_elem);
return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num)
+ pagesize - 1) & ~(pagesize - 1))
+ sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num;
}
#ifdef __KERNEL__