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yaml
---
r: 282076
b: refs/heads/master
c: b1e495b
h: refs/heads/master
v: v3
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Annie Li authored and Konrad Rzeszutek Wilk committed Nov 22, 2011
1 parent 4c5ca5f commit 6545497
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Showing 2 changed files with 11 additions and 6 deletions.
2 changes: 1 addition & 1 deletion [refs]
Original file line number Diff line number Diff line change
@@ -1,2 +1,2 @@
---
refs/heads/master: 0f9f5a9588468cddeccc9146b86798492c7cd4f5
refs/heads/master: b1e495b2fae578b1bd3ab1906cb15aac43f96fee
15 changes: 10 additions & 5 deletions trunk/drivers/xen/grant-table.c
Original file line number Diff line number Diff line change
Expand Up @@ -257,15 +257,17 @@ EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
{
u16 flags, nflags;
u16 *pflags;

nflags = gnttab_shared.v1[ref].flags;
pflags = &gnttab_shared.v1[ref].flags;
nflags = *pflags;
do {
flags = nflags;
if (flags & (GTF_reading|GTF_writing)) {
printk(KERN_ALERT "WARNING: g.e. still in use!\n");
return 0;
}
} while ((nflags = sync_cmpxchg(&gnttab_shared.v1[ref].flags, flags, 0)) != flags);
} while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);

return 1;
}
Expand Down Expand Up @@ -316,20 +318,23 @@ static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
{
unsigned long frame;
u16 flags;
u16 *pflags;

pflags = &gnttab_shared.v1[ref].flags;

/*
* If a transfer is not even yet started, try to reclaim the grant
* reference and return failure (== 0).
*/
while (!((flags = gnttab_shared.v1[ref].flags) & GTF_transfer_committed)) {
if (sync_cmpxchg(&gnttab_shared.v1[ref].flags, flags, 0) == flags)
while (!((flags = *pflags) & GTF_transfer_committed)) {
if (sync_cmpxchg(pflags, flags, 0) == flags)
return 0;
cpu_relax();
}

/* If a transfer is in progress then wait until it is completed. */
while (!(flags & GTF_transfer_completed)) {
flags = gnttab_shared.v1[ref].flags;
flags = *pflags;
cpu_relax();
}

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