[Qemu-devel] [PATCH] memory: bug 1720969: Make operations using MemoryRegionIoeventfd struct pass by pointer.

[Tristan Burgess <tburgessdev@gmail.com>]

This changes the functions memory_region_ioeventfd_equal, memory_region_ioeventfd_before, and their callers,
to pass the MemoryRegionIoeventfd struct via pointer, instead of directly passing the struct. This saves on stack space
and is considered safe practice.

Signed-off-by: Tristan Burgess <tburgessdev@gmail.com>
---
 memory.c | 44 ++++++++++++++++++++++----------------------
 1 file changed, 22 insertions(+), 22 deletions(-)

diff --git a/memory.c b/memory.c
index fc7f9b782b..a2b9bb88f3 100644
--- a/memory.c
+++ b/memory.c
@@ -173,38 +173,38 @@ struct MemoryRegionIoeventfd {
     EventNotifier *e;
 };
 
-static bool memory_region_ioeventfd_before(MemoryRegionIoeventfd a,
-                                           MemoryRegionIoeventfd b)
+static bool memory_region_ioeventfd_before(MemoryRegionIoeventfd *a,
+                                           MemoryRegionIoeventfd *b)
 {
-    if (int128_lt(a.addr.start, b.addr.start)) {
+    if (int128_lt(a->addr.start, b->addr.start)) {
         return true;
-    } else if (int128_gt(a.addr.start, b.addr.start)) {
+    } else if (int128_gt(a->addr.start, b->addr.start)) {
         return false;
-    } else if (int128_lt(a.addr.size, b.addr.size)) {
+    } else if (int128_lt(a->addr.size, b->addr.size)) {
         return true;
-    } else if (int128_gt(a.addr.size, b.addr.size)) {
+    } else if (int128_gt(a->addr.size, b->addr.size)) {
         return false;
-    } else if (a.match_data < b.match_data) {
+    } else if (a->match_data < b->match_data) {
         return true;
-    } else  if (a.match_data > b.match_data) {
+    } else  if (a->match_data > b->match_data) {
         return false;
-    } else if (a.match_data) {
-        if (a.data < b.data) {
+    } else if (a->match_data) {
+        if (a->data < b->data) {
             return true;
-        } else if (a.data > b.data) {
+        } else if (a->data > b->data) {
             return false;
         }
     }
-    if (a.e < b.e) {
+    if (a->e < b->e) {
         return true;
-    } else if (a.e > b.e) {
+    } else if (a->e > b->e) {
         return false;
     }
     return false;
 }
 
-static bool memory_region_ioeventfd_equal(MemoryRegionIoeventfd a,
-                                          MemoryRegionIoeventfd b)
+static bool memory_region_ioeventfd_equal(MemoryRegionIoeventfd *a,
+                                          MemoryRegionIoeventfd *b)
 {
     return !memory_region_ioeventfd_before(a, b)
         && !memory_region_ioeventfd_before(b, a);
@@ -791,8 +791,8 @@ static void address_space_add_del_ioeventfds(AddressSpace *as,
     while (iold < fds_old_nb || inew < fds_new_nb) {
         if (iold < fds_old_nb
             && (inew == fds_new_nb
-                || memory_region_ioeventfd_before(fds_old[iold],
-                                                  fds_new[inew]))) {
+                || memory_region_ioeventfd_before(&fds_old[iold],
+                                                  &fds_new[inew]))) {
             fd = &fds_old[iold];
             section = (MemoryRegionSection) {
                 .fv = address_space_to_flatview(as),
@@ -804,8 +804,8 @@ static void address_space_add_del_ioeventfds(AddressSpace *as,
             ++iold;
         } else if (inew < fds_new_nb
                    && (iold == fds_old_nb
-                       || memory_region_ioeventfd_before(fds_new[inew],
-                                                         fds_old[iold]))) {
+                       || memory_region_ioeventfd_before(&fds_new[inew],
+                                                         &fds_old[iold]))) {
             fd = &fds_new[inew];
             section = (MemoryRegionSection) {
                 .fv = address_space_to_flatview(as),
@@ -1443,7 +1443,7 @@ static bool memory_region_dispatch_write_eventfds(MemoryRegion *mr,
         ioeventfd.match_data = mr->ioeventfds[i].match_data;
         ioeventfd.e = mr->ioeventfds[i].e;
 
-        if (memory_region_ioeventfd_equal(ioeventfd, mr->ioeventfds[i])) {
+        if (memory_region_ioeventfd_equal(&ioeventfd, &mr->ioeventfds[i])) {
             event_notifier_set(ioeventfd.e);
             return true;
         }
@@ -2213,7 +2213,7 @@ void memory_region_add_eventfd(MemoryRegion *mr,
     }
     memory_region_transaction_begin();
     for (i = 0; i < mr->ioeventfd_nb; ++i) {
-        if (memory_region_ioeventfd_before(mrfd, mr->ioeventfds[i])) {
+        if (memory_region_ioeventfd_before(&mrfd, &mr->ioeventfds[i])) {
             break;
         }
     }
@@ -2248,7 +2248,7 @@ void memory_region_del_eventfd(MemoryRegion *mr,
     }
     memory_region_transaction_begin();
     for (i = 0; i < mr->ioeventfd_nb; ++i) {
-        if (memory_region_ioeventfd_equal(mrfd, mr->ioeventfds[i])) {
+        if (memory_region_ioeventfd_equal(&mrfd, &mr->ioeventfds[i])) {
             break;
         }
     }
-- 
2.17.0