[8/8] gnttab: drop struct active_grant_entry's gfn field for release builds

Commit Message

Jan Beulich Aug. 15, 2017, 2:42 p.m. UTC

This shrinks the size from 48 to 40 bytes bytes on 64-bit builds.

Signed-off-by: Jan Beulich <[e-mail]>

Comments

Andrew Cooper Aug. 15, 2017, 5:18 p.m. UTC | #1

On 15/08/17 15:42, Jan Beulich wrote:
> This shrinks the size from 48 to 40 bytes bytes on 64-bit builds.
>
> Signed-off-by: Jan Beulich <[e-mail]>
>
> --- a/xen/common/grant_table.c
> +++ b/xen/common/grant_table.c
> @@ -185,7 +185,12 @@ struct active_grant_entry {
>      grant_ref_t   trans_gref;
>      struct domain *trans_domain;
>      unsigned long frame;  /* Frame being granted.                     */
> +#ifndef NDEBUG
>      unsigned long gfn;    /* Guest's idea of the frame being granted. */
> +# define act_set_gfn(act, val) ((act)->gfn = (val))
> +#else
> +# define act_set_gfn(act, gfn)
> +#endif
>      spinlock_t    lock;      /* lock to protect access of this entry.
>                                  see docs/misc/grant-tables.txt for
>                                  locking protocol                      */

IMO, this would be cleaner as

static void act_set_gfn(struct active_grant_entry *act, unsigned long gfn)
{
#ifndef NDEBUG
    act->gfn = gfn;
#endif
}

Which both moves the function out of the struct definition, and takes
care of side effect evaluation differences.

~Andrew

Patch

--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -185,7 +185,12 @@  struct active_grant_entry {
     grant_ref_t   trans_gref;
     struct domain *trans_domain;
     unsigned long frame;  /* Frame being granted.                     */
+#ifndef NDEBUG
     unsigned long gfn;    /* Guest's idea of the frame being granted. */
+# define act_set_gfn(act, val) ((act)->gfn = (val))
+#else
+# define act_set_gfn(act, gfn)
+#endif
     spinlock_t    lock;      /* lock to protect access of this entry.
                                 see docs/misc/grant-tables.txt for
                                 locking protocol                      */
@@ -893,7 +898,7 @@  map_grant_ref(
                                  op->flags & GNTMAP_readonly, rd);
             if ( rc != GNTST_okay )
                 goto unlock_out_clear;
-            act->gfn = gfn;
+            act_set_gfn(act, gfn);
             act->domid = ld->domain_id;
             act->frame = frame;
             act->start = 0;
@@ -2286,7 +2291,7 @@  acquire_grant_for_copy(
             act->trans_domain = td;
             act->trans_gref = trans_gref;
             act->frame = grant_frame;
-            act->gfn = gfn_x(INVALID_GFN);
+            act_set_gfn(act, gfn_x(INVALID_GFN));
             /*
              * The actual remote remote grant may or may not be a sub-page,
              * but we always treat it as one because that blocks mappings of
@@ -2312,7 +2317,7 @@  acquire_grant_for_copy(
             rc = get_paged_frame(gfn, &grant_frame, page, readonly, rd);
             if ( rc != GNTST_okay )
                 goto unlock_out_clear;
-            act->gfn = gfn;
+            act_set_gfn(act, gfn);
             is_sub_page = 0;
             trans_page_off = 0;
             trans_length = PAGE_SIZE;
@@ -2323,7 +2328,7 @@  acquire_grant_for_copy(
                                  readonly, rd);
             if ( rc != GNTST_okay )
                 goto unlock_out_clear;
-            act->gfn = sha2->full_page.frame;
+            act_set_gfn(act, sha2->full_page.frame);
             is_sub_page = 0;
             trans_page_off = 0;
             trans_length = PAGE_SIZE;
@@ -2334,7 +2339,7 @@  acquire_grant_for_copy(
                                  readonly, rd);
             if ( rc != GNTST_okay )
                 goto unlock_out_clear;
-            act->gfn = sha2->sub_page.frame;
+            act_set_gfn(act, sha2->sub_page.frame);
             is_sub_page = 1;
             trans_page_off = sha2->sub_page.page_off;
             trans_length = sha2->sub_page.length;
@@ -3496,8 +3501,16 @@  void grant_table_warn_active_grants(stru
 
         nr_active++;
         if ( nr_active <= WARN_GRANT_MAX )
-            printk(XENLOG_G_DEBUG "Dom%d has an active grant: GFN: %lx (MFN: %lx)\n",
-                   d->domain_id, act->gfn, act->frame);
+            printk(XENLOG_G_DEBUG "Dom%d has active grant %x ("
+#ifndef NDEBUG
+                   "GFN %lx, "
+#endif
+                   "MFN: %lx)\n",
+                   d->domain_id, ref,
+#ifndef NDEBUG
+                   act->gfn,
+#endif
+                   act->frame);
         active_entry_release(act);
     }