Re: [Qemu-devel] [PATCH 1/2] blockjob: assert(cb) in the entry functions of blockjob

[Changlong Xie]

On 06/22/2016 05:50 PM, Paolo Bonzini wrote:


On 22/06/2016 11:16, Changlong Xie wrote:
Signed-off-by: Changlong Xie <xiecl.f...@cn.fujitsu.com>
---
  block/commit.c | 1 +
  block/mirror.c | 2 ++
  block/stream.c | 1 +
  3 files changed, 4 insertions(+)

Why is this useful?


commit/mirror/stream/backup use block_job_create(..., cb,..) to create 
relevant blockjob. When they finished, these jobs will invoke 
block_job_completed, then invoke job->cb() unconditionally. So i think
we need this to avoid segment fault. Actually backup has implemented this.

Thanks
        -Xie

Paolo

diff --git a/block/commit.c b/block/commit.c
index 444333b..13b55c1 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -223,6 +223,7 @@ void commit_start(BlockDriverState *bs, BlockDriverState 
*base,
      BlockDriverState *overlay_bs;
      Error *local_err = NULL;

+    assert(cb);
      assert(top != bs);
      if (top == base) {
          error_setg(errp, "Invalid files for merge: top and base are the 
same");
diff --git a/block/mirror.c b/block/mirror.c
index a04ed9c..fa2bdab 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -912,6 +912,7 @@ void mirror_start(BlockDriverState *bs, BlockDriverState 
*target,
      bool is_none_mode;
      BlockDriverState *base;

+    assert(cb);
      if (mode == MIRROR_SYNC_MODE_INCREMENTAL) {
          error_setg(errp, "Sync mode 'incremental' not supported");
          return;
@@ -935,6 +936,7 @@ void commit_active_start(BlockDriverState *bs, 
BlockDriverState *base,
      int ret;
      Error *local_err = NULL;

+    assert(cb);
      orig_base_flags = bdrv_get_flags(base);

      if (bdrv_reopen(base, bs->open_flags, errp)) {
diff --git a/block/stream.c b/block/stream.c
index c0efbda..fc34c63 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -226,6 +226,7 @@ void stream_start(BlockDriverState *bs, BlockDriverState 
*base,
  {
      StreamBlockJob *s;

+    assert(cb);
      s = block_job_create(&stream_job_driver, bs, speed, cb, opaque, errp);
      if (!s) {
          return;