xen/granttable: Refactor some code

Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Annie Li <annie.li@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 18355a53763f6811d4e9ca960816bd4183dfc99c..0518d0404942e5cc13533ef1ee5d5906d4f01546 100644 (file)
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -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;
 }
@@ -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();
        }