[Qemu-devel] [PATCH v2 08/12] Allow rdma_delete_block to work without the hash

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

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

In the next patch we remove the hash on the destination,
rdma_delete_block does two things with the hash which can be avoided:
  a) The caller passes the offset and rdma_delete_block looks it up
     in the hash; fixed by getting the caller to pass the block
  b) The hash gets recreated after deletion; fixed by making that
     conditional on the hash being initialised.

While this function is currently only used during cleanup, Michael
asked that we keep it general for future dynamic block registration
work.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/rdma.c | 27 ++++++++++++++++-----------
 trace-events     |  2 +-
 2 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/migration/rdma.c b/migration/rdma.c
index 396329c..8d99378 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -617,16 +617,19 @@ static int qemu_rdma_init_ram_blocks(RDMAContext *rdma)
     return 0;
 }
 
-static int rdma_delete_block(RDMAContext *rdma, ram_addr_t block_offset)
+/*
+ * Note: If used outside of cleanup, the caller must ensure that the destination
+ * block structures are also updated
+ */
+static int rdma_delete_block(RDMAContext *rdma, RDMALocalBlock *block)
 {
     RDMALocalBlocks *local = &rdma->local_ram_blocks;
-    RDMALocalBlock *block = g_hash_table_lookup(rdma->blockmap,
-        (void *) block_offset);
     RDMALocalBlock *old = local->block;
     int x;
 
-    assert(block);
-
+    if (rdma->blockmap) {
+        g_hash_table_remove(rdma->blockmap, (void *)(uintptr_t)block->offset);
+    }
     if (block->pmr) {
         int j;
 
@@ -659,8 +662,11 @@ static int rdma_delete_block(RDMAContext *rdma, ram_addr_t block_offset)
     g_free(block->block_name);
     block->block_name = NULL;
 
-    for (x = 0; x < local->nb_blocks; x++) {
-        g_hash_table_remove(rdma->blockmap, (void *)(uintptr_t)old[x].offset);
+    if (rdma->blockmap) {
+        for (x = 0; x < local->nb_blocks; x++) {
+            g_hash_table_remove(rdma->blockmap,
+                                (void *)(uintptr_t)old[x].offset);
+        }
     }
 
     if (local->nb_blocks > 1) {
@@ -682,8 +688,7 @@ static int rdma_delete_block(RDMAContext *rdma, ram_addr_t block_offset)
         local->block = NULL;
     }
 
-    trace_rdma_delete_block(local->nb_blocks,
-                           (uintptr_t)block->local_host_addr,
+    trace_rdma_delete_block(block, (uintptr_t)block->local_host_addr,
                            block->offset, block->length,
                             (uintptr_t)(block->local_host_addr + block->length),
                            BITS_TO_LONGS(block->nb_chunks) *
@@ -693,7 +698,7 @@ static int rdma_delete_block(RDMAContext *rdma, ram_addr_t block_offset)
 
     local->nb_blocks--;
 
-    if (local->nb_blocks) {
+    if (local->nb_blocks && rdma->blockmap) {
         for (x = 0; x < local->nb_blocks; x++) {
             g_hash_table_insert(rdma->blockmap,
                                 (void *)(uintptr_t)local->block[x].offset,
@@ -2214,7 +2219,7 @@ static void qemu_rdma_cleanup(RDMAContext *rdma)
 
     if (rdma->local_ram_blocks.block) {
         while (rdma->local_ram_blocks.nb_blocks) {
-            rdma_delete_block(rdma, rdma->local_ram_blocks.block->offset);
+            rdma_delete_block(rdma, &rdma->local_ram_blocks.block[0]);
         }
     }
 
diff --git a/trace-events b/trace-events
index 0f37a4b..7dff362 100644
--- a/trace-events
+++ b/trace-events
@@ -1452,7 +1452,7 @@ qemu_rdma_write_one_sendreg(uint64_t chunk, int len, int index, int64_t offset)
 qemu_rdma_write_one_top(uint64_t chunks, uint64_t size) "Writing %" PRIu64 " chunks, (%" PRIu64 " MB)"
 qemu_rdma_write_one_zero(uint64_t chunk, int len, int index, int64_t offset) "Entire chunk is zero, sending compress: %" PRIu64 " for %d bytes, index: %d, offset: %" PRId64
 rdma_add_block(const char *block_name, int block, uint64_t addr, uint64_t offset, uint64_t len, uint64_t end, uint64_t bits, int chunks) "Added Block: '%s':%d, addr: %" PRIu64 ", offset: %" PRIu64 " length: %" PRIu64 " end: %" PRIu64 " bits %" PRIu64 " chunks %d"
-rdma_delete_block(int block, uint64_t addr, uint64_t offset, uint64_t len, uint64_t end, uint64_t bits, int chunks) "Deleted Block: %d, addr: %" PRIu64 ", offset: %" PRIu64 " length: %" PRIu64 " end: %" PRIu64 " bits %" PRIu64 " chunks %d"
+rdma_delete_block(void *block, uint64_t addr, uint64_t offset, uint64_t len, uint64_t end, uint64_t bits, int chunks) "Deleted Block: %p, addr: %" PRIu64 ", offset: %" PRIu64 " length: %" PRIu64 " end: %" PRIu64 " bits %" PRIu64 " chunks %d"
 rdma_start_incoming_migration(void) ""
 rdma_start_incoming_migration_after_dest_init(void) ""
 rdma_start_incoming_migration_after_rdma_listen(void) ""
-- 
2.4.2