qemu_ram_foreach_block: pass up error value, and down the ramblock name

check the return value of the function it calls and error if it's non-0
Fixup qemu_rdma_init_one_block that is the only current caller,
  and rdma_add_block the only function it calls using it.

Pass the name of the ramblock to the function; helps in debugging.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Michael R. Hines <mrhines@us.ibm.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

exec.c

diff --git a/exec.c b/exec.c
index ba3f2cf..76bfc4a 100644
--- a/exec.c
+++ b/exec.c
@@ -3345,14 +3345,20 @@
     return res;
 }
 
-void qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque)
+int qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque)
 {
     RAMBlock *block;
+    int ret = 0;
 
     rcu_read_lock();
     QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
-        func(block->host, block->offset, block->used_length, opaque);
+        ret = func(block->idstr, block->host, block->offset,
+                   block->used_length, opaque);
+        if (ret) {
+            break;
+        }
     }
     rcu_read_unlock();
+    return ret;
 }
 #endif

include/exec/cpu-common.h

diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
index 43428bd..de8a720 100644
--- a/include/exec/cpu-common.h
+++ b/include/exec/cpu-common.h
@@ -126,10 +126,10 @@
 extern struct MemoryRegion io_mem_rom;
 extern struct MemoryRegion io_mem_notdirty;
 
-typedef void (RAMBlockIterFunc)(void *host_addr,
+typedef int (RAMBlockIterFunc)(const char *block_name, void *host_addr,
     ram_addr_t offset, ram_addr_t length, void *opaque);
 
-void qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque);
+int qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque);
 
 #endif
 

migration/rdma.c

diff --git a/migration/rdma.c b/migration/rdma.c
index 3671903..791ef44 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -570,10 +570,10 @@
  * in advanced before the migration starts. This tells us where the RAM blocks
  * are so that we can register them individually.
  */
-static void qemu_rdma_init_one_block(void *host_addr,
+static int qemu_rdma_init_one_block(const char *block_name, void *host_addr,
     ram_addr_t block_offset, ram_addr_t length, void *opaque)
 {
-    rdma_add_block(opaque, host_addr, block_offset, length);
+    return rdma_add_block(opaque, host_addr, block_offset, length);
 }
 
 /*