The final issue before our upstream merge is sorting out the cmpxchg on
struct grant_entry->flags, which is a 16-bit quantity (and our atomic
instructions only operate on 4/8 byte quanities).
Since it's part of a larger structure, it's safe to do the larger store,
so these patches, just like the evtchn_upcall_pending patch, should
work. I think the structure alignment will also work out...?
diff -r ab08d443113d xen/common/grant_table.c
--- a/xen/common/grant_table.c Wed Jun 21 13:36:49 2006 -0500
+++ b/xen/common/grant_table.c Wed Jun 21 13:42:23 2006 -0500
@@ -287,10 +287,10 @@ __gnttab_map_grant_ref(
if ( !(op->flags & GNTMAP_readonly) &&
!(act->pin & (GNTPIN_hstw_mask|GNTPIN_devw_mask)) )
- clear_bit(_GTF_writing, &sha->flags);
+ clear_entry_flag(_GTF_writing, &sha->flags);
if ( !act->pin )
- clear_bit(_GTF_reading, &sha->flags);
+ clear_entry_flag(_GTF_reading, &sha->flags);
unlock_out:
spin_unlock(&rd->grant_table->lock);
@@ -425,10 +425,10 @@ __gnttab_unmap_grant_ref(
if ( ((act->pin & (GNTPIN_devw_mask|GNTPIN_hstw_mask)) == 0) &&
!(flags & GNTMAP_readonly) )
- clear_bit(_GTF_writing, &sha->flags);
+ clear_entry_flag(_GTF_writing, &sha->flags);
if ( act->pin == 0 )
- clear_bit(_GTF_reading, &sha->flags);
+ clear_entry_flag(_GTF_reading, &sha->flags);
unmap_out:
op->status = rc;
@@ -889,11 +889,11 @@ gnttab_release_mappings(
}
if ( (act->pin & (GNTPIN_devw_mask|GNTPIN_hstw_mask)) == 0 )
- clear_bit(_GTF_writing, &sha->flags);
+ clear_entry_flag(_GTF_writing, &sha->flags);
}
if ( act->pin == 0 )
- clear_bit(_GTF_reading, &sha->flags);
+ clear_entry_flag(_GTF_reading, &sha->flags);
spin_unlock(&rd->grant_table->lock);
diff -r ab08d443113d xen/include/asm-ppc/grant_table.h
--- a/xen/include/asm-ppc/grant_table.h Wed Jun 21 13:36:49 2006 -0500
+++ b/xen/include/asm-ppc/grant_table.h Wed Jun 21 13:42:23 2006 -0500
@@ -6,4 +6,6 @@
#define mark_dirty(d, f) ((void )0)
#include "../asm-x86/grant_table.h"
+#define clear_entry_flag(nr, flags) clear_bit((nr), (int *)(flags));
+
#endif /* __ASM_PPC_GRANT_TABLE_H__ */
diff -r ab08d443113d xen/include/public/grant_table.h
--- a/xen/include/public/grant_table.h Wed Jun 21 13:36:49 2006 -0500
+++ b/xen/include/public/grant_table.h Wed Jun 21 13:42:23 2006 -0500
@@ -73,11 +73,7 @@
*/
struct grant_entry {
/* GTF_xxx: various type and flag information. [XEN,GST] */
-#if defined(__powerpc__)
- ulong flags;
-#else
uint16_t flags;
-#endif
/* The domain being granted foreign privileges. [GST] */
domid_t domid;
/*
And the Linux patch:
diff -r 6f3d44537b76 drivers/xen/core/gnttab.c
--- a/drivers/xen/core/gnttab.c Fri Jun 16 16:07:38 2006 -0500
+++ b/drivers/xen/core/gnttab.c Wed Jun 21 13:42:56 2006 -0500
@@ -201,7 +201,7 @@ gnttab_end_foreign_access_ref(grant_ref_
printk(KERN_ALERT "WARNING: g.e. still in use!\n");
return 0;
}
- } while ((nflags = synch_cmpxchg(&shared[ref].flags, flags, 0)) !=
+ } while ((nflags = gnttab_cmpxchg_flags(&shared[ref].flags, flags, 0))
!=
flags);
return 1;
@@ -256,7 +256,7 @@ gnttab_end_foreign_transfer_ref(grant_re
* reference and return failure (== 0).
*/
while (!((flags = shared[ref].flags) & GTF_transfer_committed)) {
- if (synch_cmpxchg(&shared[ref].flags, flags, 0) == flags)
+ if (gnttab_cmpxchg_flags(&shared[ref].flags, flags, 0) == flags)
return 0;
cpu_relax();
}
diff -r 6f3d44537b76 include/asm-powerpc/xen/asm/synch_bitops.h
--- a/include/asm-powerpc/xen/asm/synch_bitops.h Fri Jun 16 16:07:38
2006 -0500
+++ b/include/asm-powerpc/xen/asm/synch_bitops.h Wed Jun 21 13:42:56
2006 -0500
@@ -6,6 +6,8 @@
#ifdef CONFIG_SMP
#include <asm/bitops.h>
+
+#define gnttab_cmpxchg_flags(ptr,o,n) synch_cmpxchg((int *)(ptr),o,n)
#define synch_change_bit(a,b) change_bit(a,b)
#define synch_clear_bit(a,b) clear_bit(a,b)
diff -r 6f3d44537b76 include/xen/interface/grant_table.h
--- a/include/xen/interface/grant_table.h Fri Jun 16 16:07:38 2006 -0500
+++ b/include/xen/interface/grant_table.h Wed Jun 21 13:42:56 2006 -0500
@@ -73,11 +73,7 @@
*/
struct grant_entry {
/* GTF_xxx: various type and flag information. [XEN,GST] */
-#if defined(__powerpc__)
- ulong flags;
-#else
uint16_t flags;
-#endif
/* The domain being granted foreign privileges. [GST] */
domid_t domid;
/*
--
Hollis Blanchard
IBM Linux Technology Center
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