[PATCH 2/3] gnttab: Drop the frame parameter from get_paged_frame()

[Andrew Cooper <andrew.cooper3@citrix.com>]

It is redundant with the *page parameter.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: George Dunlap <George.Dunlap@eu.citrix.com>
CC: Jan Beulich <JBeulich@suse.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Tim Deegan <tim@xen.org>
CC: Wei Liu <wei.liu2@citrix.com>
---
 xen/common/grant_table.c | 50 +++++++++++++++++++++---------------------------
 1 file changed, 22 insertions(+), 28 deletions(-)

diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index 188c477..d8307b7 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -257,13 +257,13 @@ static inline void active_entry_release(struct active_grant_entry *act)
     spin_unlock(&act->lock);
 }
 
-/* Check if the page has been paged out, or needs unsharing.
-   If rc == GNTST_okay, *page contains the page struct with a ref taken.
-   Caller must do put_page(*page).
-   If any error, *page = NULL, *frame = INVALID_MFN, no ref taken. */
-static int get_paged_frame(unsigned long gfn, unsigned long *frame,
-                           struct page_info **page, bool readonly,
-                           struct domain *rd)
+/*
+ * Check if the page has been paged out, or needs unsharing.
+ * If rc == GNTST_okay, *page contains the page struct with a ref taken.
+ * Caller must do put_page(*page). If any error, *page = NULL, no ref taken.
+ */
+static int get_paged_frame(unsigned long gfn, struct page_info **page,
+                           bool readonly, struct domain *rd)
 {
     int rc = GNTST_okay;
 #if defined(P2M_PAGED_TYPES) || defined(P2M_SHARED_TYPES)
@@ -273,7 +273,6 @@ static int get_paged_frame(unsigned long gfn, unsigned long *frame,
                               (readonly) ? P2M_ALLOC : P2M_UNSHARE);
     if ( !(*page) )
     {
-        *frame = mfn_x(INVALID_MFN);
         if ( p2m_is_shared(p2mt) )
             return GNTST_eagain;
         if ( p2m_is_paging(p2mt) )
@@ -283,13 +282,12 @@ static int get_paged_frame(unsigned long gfn, unsigned long *frame,
         }
         return GNTST_bad_page;
     }
-    *frame = page_to_mfn(*page);
 #else
-    *frame = mfn_x(gfn_to_mfn(rd, _gfn(gfn)));
-    *page = mfn_valid(_mfn(*frame)) ? mfn_to_page(*frame) : NULL;
+    mfn_t mfn = gfn_to_mfn(rd, _gfn(gfn));
+
+    *page = mfn_valid(mfn) ? mfn_to_page(mfn_x(mfn)) : NULL;
     if ( (!(*page)) || (!get_page(*page, rd)) )
     {
-        *frame = mfn_x(INVALID_MFN);
         *page = NULL;
         rc = GNTST_bad_page;
     }
@@ -804,7 +802,7 @@ map_grant_ref(
     struct grant_table *lgt, *rgt;
     struct vcpu   *led;
     grant_handle_t handle;
-    unsigned long  frame = 0;
+    unsigned long  frame;
     struct page_info *pg = NULL;
     int            rc = GNTST_okay;
     u32            old_pin;
@@ -896,13 +894,12 @@ map_grant_ref(
                                 shared_entry_v1(rgt, op->ref).frame :
                                 shared_entry_v2(rgt, op->ref).full_page.frame;
 
-            rc = get_paged_frame(gfn, &frame, &pg,
-                                 op->flags & GNTMAP_readonly, rd);
+            rc = get_paged_frame(gfn, &pg, op->flags & GNTMAP_readonly, rd);
             if ( rc != GNTST_okay )
                 goto unlock_out_clear;
             act_set_gfn(act, _gfn(gfn));
             act->domid = ld->domain_id;
-            act->frame = frame;
+            act->frame = page_to_mfn(pg);
             act->start = 0;
             act->length = PAGE_SIZE;
             act->is_sub_page = false;
@@ -2163,7 +2160,6 @@ acquire_grant_for_copy(
     domid_t trans_domid;
     grant_ref_t trans_gref;
     struct domain *td;
-    unsigned long frame;
     uint16_t trans_page_off;
     uint16_t trans_length;
     bool is_sub_page;
@@ -2256,8 +2252,6 @@ acquire_grant_for_copy(
             return rc;
         }
 
-        frame = page_to_mfn(*page);
-
         /*
          * We dropped the lock, so we have to check that the grant didn't
          * change, and that nobody else tried to pin/unpin it. If anything
@@ -2265,7 +2259,8 @@ acquire_grant_for_copy(
          */
         if ( rgt->gt_version != 2 ||
              act->pin != old_pin ||
-             (old_pin && (act->domid != ldom || act->frame != frame ||
+             (old_pin && (act->domid != ldom ||
+                          act->frame != page_to_mfn(*page) ||
                           act->start != trans_page_off ||
                           act->length != trans_length ||
                           act->trans_domain != td ||
@@ -2289,7 +2284,7 @@ acquire_grant_for_copy(
             act->length = trans_length;
             act->trans_domain = td;
             act->trans_gref = trans_gref;
-            act->frame = frame;
+            act->frame = page_to_mfn(*page);
             act_set_gfn(act, INVALID_GFN);
             /*
              * The actual remote remote grant may or may not be a sub-page,
@@ -2313,7 +2308,7 @@ acquire_grant_for_copy(
         {
             unsigned long gfn = shared_entry_v1(rgt, gref).frame;
 
-            rc = get_paged_frame(gfn, &frame, page, readonly, rd);
+            rc = get_paged_frame(gfn, page, readonly, rd);
             if ( rc != GNTST_okay )
                 goto unlock_out_clear;
             act_set_gfn(act, _gfn(gfn));
@@ -2323,8 +2318,7 @@ acquire_grant_for_copy(
         }
         else if ( !(sha2->hdr.flags & GTF_sub_page) )
         {
-            rc = get_paged_frame(sha2->full_page.frame, &frame, page,
-                                 readonly, rd);
+            rc = get_paged_frame(sha2->full_page.frame, page, readonly, rd);
             if ( rc != GNTST_okay )
                 goto unlock_out_clear;
             act_set_gfn(act, _gfn(sha2->full_page.frame));
@@ -2334,8 +2328,7 @@ acquire_grant_for_copy(
         }
         else
         {
-            rc = get_paged_frame(sha2->sub_page.frame, &frame, page,
-                                 readonly, rd);
+            rc = get_paged_frame(sha2->sub_page.frame, page, readonly, rd);
             if ( rc != GNTST_okay )
                 goto unlock_out_clear;
             act_set_gfn(act, _gfn(sha2->sub_page.frame));
@@ -2352,7 +2345,7 @@ acquire_grant_for_copy(
             act->length = trans_length;
             act->trans_domain = td;
             act->trans_gref = trans_gref;
-            act->frame = frame;
+            act->frame = page_to_mfn(*page);
         }
     }
     else
@@ -2515,12 +2508,13 @@ static int gnttab_copy_claim_buf(const struct gnttab_copy *op,
     }
     else
     {
-        rc = get_paged_frame(ptr->u.gmfn, &buf->frame, &buf->page,
+        rc = get_paged_frame(ptr->u.gmfn, &buf->page,
                              buf->read_only, buf->domain);
         if ( rc != GNTST_okay )
             PIN_FAIL(out, rc,
                      "source frame %"PRI_xen_pfn" invalid.\n", ptr->u.gmfn);
 
+        buf->frame = page_to_mfn(buf->page);
         buf->ptr.u.gmfn = ptr->u.gmfn;
         buf->ptr.offset = 0;
         buf->len = PAGE_SIZE;
-- 
2.1.4


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