Like other setters here these functions should take a lock.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/dirty-bitmap.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index bd04e991b1..2a0bcd9e51 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -397,15 +397,19 @@ void bdrv_remove_persistent_dirty_bitmap(BlockDriverState *bs,
 /* Called with BQL taken.  */
 void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
 {
+    bdrv_dirty_bitmap_lock(bitmap);
     assert(!bdrv_dirty_bitmap_frozen(bitmap));
     bitmap->disabled = true;
+    bdrv_dirty_bitmap_unlock(bitmap);
 }
 
 /* Called with BQL taken.  */
 void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
 {
+    bdrv_dirty_bitmap_lock(bitmap);
     assert(!bdrv_dirty_bitmap_frozen(bitmap));
     bitmap->disabled = false;
+    bdrv_dirty_bitmap_unlock(bitmap);
 }
 
 BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs)
-- 
2.11.1

On 11/13/2017 10:20 AM, Vladimir Sementsov-Ogievskiy wrote:
> Like other setters here these functions should take a lock.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  block/dirty-bitmap.c | 4 ++++
>  1 file changed, 4 insertions(+)

Should this patch be in 2.11?

> 
> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
> index bd04e991b1..2a0bcd9e51 100644
> --- a/block/dirty-bitmap.c
> +++ b/block/dirty-bitmap.c
> @@ -397,15 +397,19 @@ void bdrv_remove_persistent_dirty_bitmap(BlockDriverState *bs,
>  /* Called with BQL taken.  */
>  void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
>  {
> +    bdrv_dirty_bitmap_lock(bitmap);
>      assert(!bdrv_dirty_bitmap_frozen(bitmap));
>      bitmap->disabled = true;
> +    bdrv_dirty_bitmap_unlock(bitmap);

Why do we need this lock in addition to BQL?

>  }
>  
>  /* Called with BQL taken.  */
>  void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
>  {
> +    bdrv_dirty_bitmap_lock(bitmap);
>      assert(!bdrv_dirty_bitmap_frozen(bitmap));
>      bitmap->disabled = false;
> +    bdrv_dirty_bitmap_unlock(bitmap);

Again, why do we need this in addition to BQL?

The commit message needs more details about a scenario where our
existing BQL lock is insufficient to prevent misuse of bitmap->disabled.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

13.11.2017 20:50, Eric Blake wrote:
> On 11/13/2017 10:20 AM, Vladimir Sementsov-Ogievskiy wrote:
>> Like other setters here these functions should take a lock.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> ---
>>   block/dirty-bitmap.c | 4 ++++
>>   1 file changed, 4 insertions(+)
> Should this patch be in 2.11?
>
>> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
>> index bd04e991b1..2a0bcd9e51 100644
>> --- a/block/dirty-bitmap.c
>> +++ b/block/dirty-bitmap.c
>> @@ -397,15 +397,19 @@ void bdrv_remove_persistent_dirty_bitmap(BlockDriverState *bs,
>>   /* Called with BQL taken.  */
>>   void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
>>   {
>> +    bdrv_dirty_bitmap_lock(bitmap);
>>       assert(!bdrv_dirty_bitmap_frozen(bitmap));
>>       bitmap->disabled = true;
>> +    bdrv_dirty_bitmap_unlock(bitmap);
> Why do we need this lock in addition to BQL?

in fact, comment about BQL should be dropped.

block_int.h:

     /* Writing to the list requires the BQL _and_ the dirty_bitmap_mutex.
      * Reading from the list can be done with either the BQL or the
      * dirty_bitmap_mutex.  Modifying a bitmap only requires
      * dirty_bitmap_mutex.  */
     QemuMutex dirty_bitmap_mutex;

>
>>   }
>>   
>>   /* Called with BQL taken.  */
>>   void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
>>   {
>> +    bdrv_dirty_bitmap_lock(bitmap);
>>       assert(!bdrv_dirty_bitmap_frozen(bitmap));
>>       bitmap->disabled = false;
>> +    bdrv_dirty_bitmap_unlock(bitmap);
> Again, why do we need this in addition to BQL?

and here.

>
> The commit message needs more details about a scenario where our
> existing BQL lock is insufficient to prevent misuse of bitmap->disabled.
>


-- 
Best regards,
Vladimir

13.11.2017 20:50, Eric Blake wrote:
> On 11/13/2017 10:20 AM, Vladimir Sementsov-Ogievskiy wrote:
>> Like other setters here these functions should take a lock.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> ---
>>   block/dirty-bitmap.c | 4 ++++
>>   1 file changed, 4 insertions(+)
> Should this patch be in 2.11?


these functions are unused now, so, no, it's not necessary

>
>> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
>> index bd04e991b1..2a0bcd9e51 100644
>> --- a/block/dirty-bitmap.c
>> +++ b/block/dirty-bitmap.c
>> @@ -397,15 +397,19 @@ void bdrv_remove_persistent_dirty_bitmap(BlockDriverState *bs,
>>   /* Called with BQL taken.  */
>>   void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
>>   {
>> +    bdrv_dirty_bitmap_lock(bitmap);
>>       assert(!bdrv_dirty_bitmap_frozen(bitmap));
>>       bitmap->disabled = true;
>> +    bdrv_dirty_bitmap_unlock(bitmap);
> Why do we need this lock in addition to BQL?
>
>>   }
>>   
>>   /* Called with BQL taken.  */
>>   void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
>>   {
>> +    bdrv_dirty_bitmap_lock(bitmap);
>>       assert(!bdrv_dirty_bitmap_frozen(bitmap));
>>       bitmap->disabled = false;
>> +    bdrv_dirty_bitmap_unlock(bitmap);
> Again, why do we need this in addition to BQL?
>
> The commit message needs more details about a scenario where our
> existing BQL lock is insufficient to prevent misuse of bitmap->disabled.
>


-- 
Best regards,
Vladimir