# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID 52020caa244f9c86c434b8332783c1edc658d852
# Parent e336e186e5f96a0e93f842ca3a2e39601c2a0193
Change semantics of gnttab_transfer to take the page away
from the calling domain, even on error (except for special
error GNTST_bad_page). This has a knock-on advantage of
simplifying Linux's netback driver.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
diff -r e336e186e5f9 -r 52020caa244f
linux-2.6-xen-sparse/drivers/xen/netback/netback.c
--- a/linux-2.6-xen-sparse/drivers/xen/netback/netback.c Mon Nov 21
16:30:43 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/netback.c Mon Nov 21
17:10:35 2005
@@ -97,27 +97,6 @@
mfn = mfn_list[--alloc_index];
spin_unlock_irqrestore(&mfn_lock, flags);
return mfn;
-}
-
-static void free_mfn(unsigned long mfn)
-{
- unsigned long flags;
- struct xen_memory_reservation reservation = {
- .extent_start = &mfn,
- .nr_extents = 1,
- .extent_order = 0,
- .domid = DOMID_SELF
- };
- spin_lock_irqsave(&mfn_lock, flags);
- if ( alloc_index != MAX_MFN_ALLOC )
- mfn_list[alloc_index++] = mfn;
- else {
- int ret;
- ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
- &reservation);
- BUG_ON(ret != 1);
- }
- spin_unlock_irqrestore(&mfn_lock, flags);
}
static inline void maybe_schedule_tx_action(void)
@@ -306,14 +285,18 @@
netif->stats.tx_packets++;
/* The update_va_mapping() must not fail. */
- BUG_ON(mcl[0].result != 0);
+ BUG_ON(mcl->result != 0);
/* Check the reassignment error code. */
status = NETIF_RSP_OKAY;
if (gop->status != 0) {
DPRINTK("Bad status %d from grant transfer to DOM%u\n",
gop->status, netif->domid);
- free_mfn(old_mfn);
+ /*
+ * Page no longer belongs to us unless GNTST_bad_page,
+ * but that should be a fatal error anyway.
+ */
+ BUG_ON(gop->status == GNTST_bad_page);
status = NETIF_RSP_ERROR;
}
irq = netif->irq;
diff -r e336e186e5f9 -r 52020caa244f xen/common/grant_table.c
--- a/xen/common/grant_table.c Mon Nov 21 16:30:43 2005
+++ b/xen/common/grant_table.c Mon Nov 21 17:10:35 2005
@@ -714,26 +714,18 @@
/* Read from caller address space. */
if ( unlikely(__copy_from_user(&gop, &uop[i], sizeof(gop))) )
{
- /* Caller error: bail immediately. */
DPRINTK("gnttab_transfer: error reading req %d/%d\n", i, count);
- return -EFAULT;
+ (void)__put_user(GNTST_bad_page, &uop[i].status);
+ return -EFAULT; /* This is *very* fatal. */
}
/* Check the passed page frame for basic validity. */
page = &frame_table[gop.mfn];
if ( unlikely(!pfn_valid(gop.mfn) || IS_XEN_HEAP_FRAME(page)) )
{
- /* Caller error: bail immediately. */
DPRINTK("gnttab_transfer: out-of-range or xen frame %lx\n",
(unsigned long)gop.mfn);
- return -EINVAL;
- }
-
- /* Find the target domain. */
- if ( unlikely((e = find_domain_by_id(gop.domid)) == NULL) )
- {
- DPRINTK("gnttab_transfer: can't find domain %d\n", gop.domid);
- (void)__put_user(GNTST_bad_domain, &uop[i].status);
+ (void)__put_user(GNTST_bad_page, &uop[i].status);
continue;
}
@@ -752,15 +744,14 @@
x = y;
if (unlikely((x & (PGC_count_mask|PGC_allocated)) !=
(1 | PGC_allocated)) || unlikely(_nd != _d)) {
- /* Caller error: bail immediately. */
DPRINTK("gnttab_transfer: Bad page %p: ed=%p(%u), sd=%p,"
" caf=%08x, taf=%" PRtype_info "\n",
(void *) page_to_pfn(page),
d, d->domain_id, unpickle_domptr(_nd), x,
page->u.inuse.type_info);
spin_unlock(&d->page_alloc_lock);
- put_domain(e);
- return -EINVAL;
+ (void)__put_user(GNTST_bad_page, &uop[i].status);
+ continue;
}
__asm__ __volatile__(
LOCK_PREFIX "cmpxchg8b %2"
@@ -778,6 +769,16 @@
list_del(&page->list);
spin_unlock(&d->page_alloc_lock);
+
+ /* Find the target domain. */
+ if ( unlikely((e = find_domain_by_id(gop.domid)) == NULL) )
+ {
+ DPRINTK("gnttab_transfer: can't find domain %d\n", gop.domid);
+ (void)__put_user(GNTST_bad_domain, &uop[i].status);
+ page->count_info &= ~(PGC_count_mask|PGC_allocated);
+ free_domheap_page(page);
+ continue;
+ }
spin_lock(&e->page_alloc_lock);
@@ -797,6 +798,8 @@
spin_unlock(&e->page_alloc_lock);
put_domain(e);
(void)__put_user(GNTST_general_error, &uop[i].status);
+ page->count_info &= ~(PGC_count_mask|PGC_allocated);
+ free_domheap_page(page);
continue;
}
diff -r e336e186e5f9 -r 52020caa244f xen/common/page_alloc.c
--- a/xen/common/page_alloc.c Mon Nov 21 16:30:43 2005
+++ b/xen/common/page_alloc.c Mon Nov 21 17:10:35 2005
@@ -645,7 +645,9 @@
}
else
{
- /* Freeing an anonymous domain-heap page. */
+ /* Freeing anonymous domain-heap pages. */
+ for ( i = 0; i < (1 << order); i++ )
+ pg[i].u.free.cpumask = CPU_MASK_NONE;
free_heap_pages(pfn_dom_zone_type(page_to_pfn(pg)), pg, order);
drop_dom_ref = 0;
}
diff -r e336e186e5f9 -r 52020caa244f xen/include/public/grant_table.h
--- a/xen/include/public/grant_table.h Mon Nov 21 16:30:43 2005
+++ b/xen/include/public/grant_table.h Mon Nov 21 17:10:35 2005
@@ -215,9 +215,12 @@
} gnttab_dump_table_t;
/*
- * GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The
- * foreign domain has previously registered the details of the transfer.
- * These can be identified from <handle>, a grant reference.
+ * GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The
+ * foreign domain has previously registered its interest in the transfer via
+ * <domid, ref>.
+ *
+ * Note that, even if the transfer fails, the specified page no longer belongs
+ * to the calling domain *unless* the error is GNTST_bad_page.
*/
#define GNTTABOP_transfer 4
typedef struct {
@@ -269,6 +272,7 @@
#define GNTST_bad_dev_addr (-6) /* Inappropriate device address to unmap.*/
#define GNTST_no_device_space (-7) /* Out of space in I/O MMU. */
#define GNTST_permission_denied (-8) /* Not enough privilege for operation. */
+#define GNTST_bad_page (-9) /* Specified page was invalid for op. */
#define GNTTABOP_error_msgs { \
"okay", \
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