[PULL 13/18] migration: Move static var in ram_block_from_stream() into global

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: Peter Xu <peterx@redhat.com>

Static variable is very unfriendly to threading of ram_block_from_stream().
Move it into MigrationIncomingState.

Make the incoming state pointer to be passed over to ram_block_from_stream() on
both caller sites.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20220301083925.33483-8-peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/migration.h |  3 ++-
 migration/ram.c       | 13 +++++++++----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/migration/migration.h b/migration/migration.h
index 8445e1d14a..d8b9850eae 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -66,7 +66,8 @@ typedef struct {
 /* State for the incoming migration */
 struct MigrationIncomingState {
     QEMUFile *from_src_file;
-
+    /* Previously received RAM's RAMBlock pointer */
+    RAMBlock *last_recv_block;
     /* A hook to allow cleanup at the end of incoming migration */
     void *transport_data;
     void (*transport_cleanup)(void *data);
diff --git a/migration/ram.c b/migration/ram.c
index a9d0d100bd..170e522a1f 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3185,12 +3185,14 @@ static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host)
  *
  * Returns a pointer from within the RCU-protected ram_list.
  *
+ * @mis: the migration incoming state pointer
  * @f: QEMUFile where to read the data from
  * @flags: Page flags (mostly to see if it's a continuation of previous block)
  */
-static inline RAMBlock *ram_block_from_stream(QEMUFile *f, int flags)
+static inline RAMBlock *ram_block_from_stream(MigrationIncomingState *mis,
+                                              QEMUFile *f, int flags)
 {
-    static RAMBlock *block;
+    RAMBlock *block = mis->last_recv_block;
     char id[256];
     uint8_t len;
 
@@ -3217,6 +3219,8 @@ static inline RAMBlock *ram_block_from_stream(QEMUFile *f, int flags)
         return NULL;
     }
 
+    mis->last_recv_block = block;
+
     return block;
 }
 
@@ -3669,7 +3673,7 @@ static int ram_load_postcopy(QEMUFile *f)
         trace_ram_load_postcopy_loop((uint64_t)addr, flags);
         if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE |
                      RAM_SAVE_FLAG_COMPRESS_PAGE)) {
-            block = ram_block_from_stream(f, flags);
+            block = ram_block_from_stream(mis, f, flags);
             if (!block) {
                 ret = -EINVAL;
                 break;
@@ -3881,6 +3885,7 @@ void colo_flush_ram_cache(void)
  */
 static int ram_load_precopy(QEMUFile *f)
 {
+    MigrationIncomingState *mis = migration_incoming_get_current();
     int flags = 0, ret = 0, invalid_flags = 0, len = 0, i = 0;
     /* ADVISE is earlier, it shows the source has the postcopy capability on */
     bool postcopy_advised = postcopy_is_advised();
@@ -3919,7 +3924,7 @@ static int ram_load_precopy(QEMUFile *f)
 
         if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE |
                      RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE)) {
-            RAMBlock *block = ram_block_from_stream(f, flags);
+            RAMBlock *block = ram_block_from_stream(mis, f, flags);
 
             host = host_from_ram_block_offset(block, addr);
             /*
-- 
2.35.1